@article{atkins_byrne_bohnenstiehl_wegmann_2022, title={A Morphometric Investigation of Large-Scale Crustal Shortening on Mars}, volume={127}, ISSN={["2169-9100"]}, url={https://doi.org/10.1029/2021JE007110}, DOI={10.1029/2021JE007110}, abstractNote={Mars' surface exhibits abundant topographic expressions of large thrust fault‐related folds that have been attributed to global planetary contraction. Morphometric analyses of such structures provide insight into their growth history. With global THEMIS imagery and HRSC–MOLA topographic data, 49 thrusts with lengths between 35 and 544 km were mapped across Mars' surface. Assuming planar fault geometries with dips of 30°, the average maximum displacement‐length ratio (Dmax/L) of these structures is 6.1 × 10−3 ± 1.4 × 10−3, with smaller ratios observed for faults within the northern lowlands (2.9 × 10−3 ± 0.9 × 10−3) compared to the southern highlands (9.2 × 10−3 ± 1.9 × 10−3). However, these differences may be accounted for if mechanical layering in the northern lowland crust promotes either a shallowing of the fault dip angle relative to the southern highlands or the development of ramp‐flat geometries such that the topographic scarp height may under‐estimate the total fault displacement or a combination of these two scenarios together. Alternatively, these Dmax/L patterns may reflect hemispheric differences in the brittle‐ductile transition (BDT) depth; however, the observed pattern is stratigraphically inconsistent with the Martian crustal dichotomy, whereby the northern lowlands have thinner (or denser) crust and therefore presumably a deeper BDT than the southern highlands. Fault displacement‐length profiles are commonly asymmetric, with multiple local minima observed along their lengths. Spectral analysis of these profiles, using Fourier‐ and S‐Transforms, indicates power at a range of spatial frequencies, reflecting complex growth and linkage histories, with peak spectral frequency, or number of segments, being negatively correlated with the Dmax/L ratios.}, number={5}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS}, publisher={American Geophysical Union (AGU)}, author={Atkins, R. M. and Byrne, P. K. and Bohnenstiehl, D. R. and Wegmann, K. W.}, year={2022}, month={May} }
 @misc{rolf_weller_gulcher_byrne_joseph g. o'rourke_herrick_bjonnes_davaille_ghail_gillmann_et al._2022, title={Dynamics and Evolution of Venus' Mantle Through Time}, volume={218}, ISSN={["1572-9672"]}, DOI={10.1007/s11214-022-00937-9}, abstractNote={Abstract The dynamics and evolution of Venus’ mantle are of first-order relevance for the origin and modification of the tectonic and volcanic structures we observe on Venus today. Solid-state convection in the mantle induces stresses into the lithosphere and crust that drive deformation leading to tectonic signatures. Thermal coupling of the mantle with the atmosphere and the core leads to a distinct structure with substantial lateral heterogeneity, thermally and compositionally. These processes ultimately shape Venus’ tectonic regime and provide the framework to interpret surface observations made on Venus, such as gravity and topography. Tectonic and convective processes are continuously changing through geological time, largely driven by the long-term thermal and compositional evolution of Venus’ mantle. To date, no consensus has been reached on the geodynamic regime Venus’ mantle is presently in, mostly because observational data remains fragmentary. In contrast to Earth, Venus’ mantle does not support the existence of continuous plate tectonics on its surface. However, the planet’s surface signature substantially deviates from those of tectonically largely inactive bodies, such as Mars, Mercury, or the Moon. This work reviews the current state of knowledge of Venus’ mantle dynamics and evolution through time, focussing on a dynamic system perspective. Available observations to constrain the deep interior are evaluated and their insufficiency to pin down Venus’ evolutionary path is emphasised. Future missions will likely revive the discussion of these open issues and boost our current understanding by filling current data gaps; some promising avenues are discussed in this chapter.}, number={8}, journal={SPACE SCIENCE REVIEWS}, author={Rolf, Tobias and Weller, Matt and Gulcher, Anna and Byrne, Paul and Joseph G. O'Rourke and Herrick, Robert and Bjonnes, Evan and Davaille, Anne and Ghail, Richard and Gillmann, Cedric and et al.}, year={2022}, month={Dec} }
 @article{byrne_krishnamoorthy_2022, title={Estimates on the Frequency of Volcanic Eruptions on Venus}, volume={127}, ISSN={["2169-9100"]}, DOI={10.1029/2021JE007040}, abstractNote={Venus hosts many thousands of volcanic landforms, including individual edifices, volcanotectonic structures, and vast expanses of effusively emplaced plains lavas. Numerous lines of circumstantial evidence together suggest that the planet is volcanically active today. Although previous studies have calculated volcanic eruptive fluxes on the basis of the volumes of lava needed to bury craters of various diameters on Venus, no estimates of the frequency of volcanic eruptions on the planet yet exist. In this study, we analyzed records for eruptive events on Earth between 1 January 1980 and 21 January 2021 for which data on duration and eruption intensity were available, and classified those events by tectonic setting. We then extrapolated those results to Venus by a simple scaling factor. We estimate that as many as 120 discrete eruptions, from individual volcanic edifices and of any duration and intensity, may occur on Venus per Earth year. Further, within any given 60‐day window—a nominal timeframe over which an aerial platform capable of detecting volcanic activity might operate in the middle Venus atmosphere—we expect about four new eruptions to begin, with that number rising to almost eight when both new events and those ending within 100 days of the main eruption are included, or to as many as 20 when considering activity that lasts for 1,000 days. Several complementary techniques exist with which to search for volcanic eruptions at Venus, either from orbit, within the atmosphere, or on the surface, that can be used to test the estimates we make here.}, number={1}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS}, author={Byrne, Paul K. and Krishnamoorthy, Siddharth}, year={2022}, month={Jan} }
 @article{ernst_chabot_klima_kubota_rogers_byrne_hauck_vander kaaden_vervack_besse_et al._2022, title={Science Goals and Mission Concept for a Landed Investigation of Mercury}, volume={3}, ISSN={["2632-3338"]}, DOI={10.3847/PSJ/ac1c0f}, abstractNote={Mercury holds valuable clues to the distribution of elements at the birth of the solar system and how planets form and evolve in close proximity to their host stars. This Mercury Lander mission concept returns in situ measurements that address fundamental science questions raised by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission’s pioneering exploration of Mercury. Such measurements are needed to understand Mercury's unique mineralogy and geochemistry, characterize the proportionally massive core's structure, measure the planet's active and ancient magnetic fields at the surface, investigate the processes that alter the surface and produce the exosphere, and provide ground truth for remote data sets. The mission concept achieves one full Mercury year (∼88 Earth days) of surface operations with an 11-instrument, high-heritage payload delivered to a landing site within Mercury's widely distributed low-reflectance material, and it addresses science goals encompassing geochemistry, geophysics, the Mercury space environment, and geology. The spacecraft launches in 2035, and the four-stage flight system uses a solar electric propulsion cruise stage to reach Mercury in 2045. Landing is at dusk to meet thermal requirements, permitting ∼30 hr of sunlight for initial observations. The radioisotope-powered lander continues operations through the Mercury night. Direct-to-Earth communication is possible for the initial 3 weeks of landed operations, drops out for 6 weeks, and resumes for the final month. Thermal conditions exceed lander operating temperatures shortly after sunrise, ending operations. Approximately 11 GB of data are returned to Earth. The cost estimate demonstrates that a Mercury Lander mission is feasible and compelling as a New Frontiers–class mission.}, number={3}, journal={PLANETARY SCIENCE JOURNAL}, author={Ernst, Carolyn M. and Chabot, Nancy L. and Klima, Rachel L. and Kubota, Sanae and Rogers, Gabe and Byrne, Paul K. and Hauck, Steven A. and Vander Kaaden, Kathleen E. and Vervack, Ronald J. and Besse, Sebastien and et al.}, year={2022}, month={Mar} }
 @article{byrne_ghail_sengor_james_klimczak_solomon_2021, title={A globally fragmented and mobile lithosphere on Venus}, volume={118}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.2025919118}, abstractNote={Significance We have identified a pattern of tectonic deformation on Venus that suggests that many of the planet’s lowlands have fragmented into discrete crustal blocks, and that these blocks have moved relative to each other in the geologically recent past. These motions may be the result of mantle convection and, if so, constitute a style of interior–surface coupling not seen elsewhere in the inner Solar System except for continental interiors on Earth. Venus’ fragmented, mobile lithosphere may offer a framework for understanding how tectonics on Earth operated in the Archean. Venus has been thought to possess a globally continuous lithosphere, in contrast to the mosaic of mobile tectonic plates that characterizes Earth. However, the Venus surface has been extensively deformed, and convection of the underlying mantle, possibly acting in concert with a low-strength lower crust, has been suggested as a source of some surface horizontal strains. The extent of surface mobility on Venus driven by mantle convection, however, and the style and scale of its tectonic expression have been unclear. We report a globally distributed set of crustal blocks in the Venus lowlands that show evidence for having rotated and/or moved laterally relative to one another, akin to jostling pack ice. At least some of this deformation on Venus postdates the emplacement of the locally youngest plains materials. Lithospheric stresses calculated from interior viscous flow models consistent with long-wavelength gravity and topography are sufficient to drive brittle failure in the upper Venus crust in all areas where these blocks are present, confirming that interior convective motion can provide a mechanism for driving deformation at the surface. The limited but widespread lithospheric mobility of Venus, in marked contrast to the tectonic styles indicative of a static lithosphere on Mercury, the Moon, and Mars, may offer parallels to interior–surface coupling on the early Earth, when global heat flux was substantially higher, and the lithosphere generally thinner, than today.}, number={26}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Byrne, Paul K. and Ghail, Richard C. and Sengor, A. M. Celal and James, Peter B. and Klimczak, Christian and Solomon, Sean C.}, year={2021}, month={Jun} }
 @misc{mendez_rivera-valentin_schulze-makuch_filiberto_ramirez_wood_davila_mckay_ceballos_jusino-maldonado_et al._2021, title={Habitability Models for Astrobiology}, volume={21}, ISSN={["1557-8070"]}, DOI={10.1089/ast.2020.2342}, abstractNote={Habitability has been generally defined as the capability of an environment to support life. Ecologists have been using Habitat Suitability Models (HSMs) for more than four decades to study the habitability of Earth from local to global scales. Astrobiologists have been proposing different habitability models for some time, with little integration and consistency among them, being different in function to those used by ecologists. Habitability models are not only used to determine whether environments are habitable, but they also are used to characterize what key factors are responsible for the gradual transition from low to high habitability states. Here we review and compare some of the different models used by ecologists and astrobiologists and suggest how they could be integrated into new habitability standards. Such standards will help improve the comparison and characterization of potentially habitable environments, prioritize target selections, and study correlations between habitability and biosignatures. Habitability models are the foundation of planetary habitability science, and the synergy between ecologists and astrobiologists is necessary to expand our understanding of the habitability of Earth, the Solar System, and extrasolar planets.}, number={8}, journal={ASTROBIOLOGY}, author={Mendez, Abel and Rivera-Valentin, Edgard G. and Schulze-Makuch, Dirk and Filiberto, Justin and Ramirez, Ramses M. and Wood, Tana E. and Davila, Alfonso and McKay, Chris and Ceballos, Kevin N. Ortiz and Jusino-Maldonado, Marcos and et al.}, year={2021}, month={Aug}, pages={1017–1027} }
 @article{wright_byrne_rothery_2021, title={Planet Mercury: Volcanism in a theatre of global contraction, with examples from the Hokusai quadrangle}, volume={417}, ISSN={["1872-6097"]}, DOI={10.1016/j.jvolgeores.2021.107300}, abstractNote={Mercury's geological history has been dominated by global contraction caused by secular cooling of the planet's interior. This cooling has had a profound effect on the expression of the planet's volcanism and tectonism, and the expressions of these two surface evolutionary processes are deeply intertwined. Here, we use case studies from the Hokusai quadrangle of Mercury to gain insight into the interplay between Mercury's volcanism and tectonism, which we review throughout this paper. We perform the first crater size–frequency analysis of the southernmost extent of Borealis Planitia, Mercury's largest expanse of volcanic plains, and find that it formed ~3.8–3.7 Ga. We discuss the importance of “intermediate plains”, a widespread unit in the Hokusai quadrangle, as the manifestation of relatively low-volume effusions with an uncertain stratigraphic relationship with Borealis Planitia. Finally, we detail the formation of the Suge Facula pitted ground during the geological history of Rachmaninoff crater, and hypothesise that such textures probably formed more widely on Mercury but have often either been buried by thick lava flows or otherwise obscured. Unanswered questions in this work can be used to drive the next phase of Mercury exploration and research with the arrival of the BepiColombo mission.}, journal={JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH}, author={Wright, Jack and Byrne, Paul K. and Rothery, David A.}, year={2021}, month={Sep} }
 @article{kling_byrne_atkins_wegmann_2021, title={Tectonic Deformation and Volatile Loss in the Formation of Noctis Labyrinthus, Mars}, volume={126}, ISSN={["2169-9100"]}, url={https://doi.org/10.1029/2020JE006555}, DOI={10.1029/2020JE006555}, abstractNote={Noctis Labyrinthus is a little‐studied and structurally complex area situated between the Tharsis Rise and Valles Marineris on Mars. Noctis Labyrinthus is dissected by normal faults that form horst and graben, pit craters situated inside the graben, and large troughs that cross‐cut both graben and pit craters. Mass wasting, periglacial, and some erosive fluvial features are observed at the bases of the troughs, suggesting that the troughs hosted liquid and perhaps even ice at some point in the past. We mapped and analyzed these structural and morphological features in Noctis Labyrinthus to establish the region's formational history. Fault throw profiles, combined with morphometric data from pit craters, were used to assess how the pit craters relate to the much larger troughs in the region and whether those troughs were formed by extensional tectonic deformation alone. This comparative analysis suggests that some pit craters grew deeper than the amount of throw accommodated by their bounding faults. We hypothesize that layers with subsurface volatiles (such as ground ice) were intersected and exposed by the larger Noctis Labyrinthus pit craters, enabling sublimation that further promoted mass wasting and the growth and coalescence of pits and graben into the large troughs. Under this scenario, subsurface volatiles played an important role in forming this structurally complex region, and may still be present there.}, number={11}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS}, publisher={American Geophysical Union (AGU)}, author={Kling, Corbin L. and Byrne, Paul K. and Atkins, Rachel M. and Wegmann, Karl W.}, year={2021}, month={Nov} }
 @article{byrne_foley_violay_heap_mikhail_2021, title={The Effects of Planetary and Stellar Parameters on Brittle Lithospheric Thickness}, volume={126}, ISSN={["2169-9100"]}, DOI={10.1029/2021JE006952}, abstractNote={The thickness of the brittle lithosphere—the outer portion of a planetary body that fails via fracturing—plays a key role in the geological processes of that body. The properties of both a planet and its host star can influence that thickness, and the potential range of those properties exceeds what we see in the Solar System. To understand how planetary and stellar parameters influence brittle lithospheric thickness generally, we modeled a comprehensive suite of combinations of planetary mass, surface and mantle temperature, heat flux, and strain rate. Surface temperature is the dominant factor governing the thickness of the brittle layer: smaller and older planets generally have thick brittle lithospheres, akin to those of Mercury and Mars, whereas larger, younger planets have thinner brittle lithospheres that may be comparable to the Venus lowlands. But certain combinations of these parameters yield worlds with exceedingly thin brittle layers. We predict that such bodies have little elevated topography and limited volatile cycling and weathering, which can be tested by future telescopic observations of known extrasolar planets.}, number={11}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS}, author={Byrne, Paul K. and Foley, Bradford J. and Violay, Marie E. S. and Heap, Michael J. and Mikhail, Sami}, year={2021}, month={Nov} }
 @misc{kane_arney_byrne_dalba_desch_horner_izenberg_mandt_meadows_quick_2021, title={The Fundamental Connections between the Solar System and Exoplanetary Science}, volume={126}, ISSN={["2169-9100"]}, DOI={10.1029/2020JE006643}, abstractNote={Over the past several decades, thousands of planets have been discovered outside our Solar System. These planets exhibit enormous diversity, and their large numbers provide a statistical opportunity to place our Solar System within the broader context of planetary structure, atmospheres, architectures, formation, and evolution. Meanwhile, the field of exoplanetary science is rapidly forging onward toward a goal of atmospheric characterization, inferring surface conditions and interiors, and assessing the potential for habitability. However, the interpretation of exoplanet data requires the development and validation of exoplanet models that depend on in situ data that, in the foreseeable future, are only obtainable from our Solar System. Thus, planetary and exoplanetary science would both greatly benefit from a symbiotic relationship with a two‐way flow of information. Here, we describe the critical lessons and outstanding questions from planetary science, the study of which are essential for addressing fundamental aspects for a variety of exoplanetary topics. We outline these lessons and questions for the major categories of Solar System bodies, including the terrestrial planets, the giant planets, moons, and minor bodies. We provide a discussion of how many of these planetary science issues may be translated into exoplanet observables that will yield critical insight into current and future exoplanet discoveries.}, number={2}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS}, author={Kane, Stephen R. and Arney, Giada N. and Byrne, Paul K. and Dalba, Paul A. and Desch, Steven J. and Horner, Jonti and Izenberg, Noam R. and Mandt, Kathleen E. and Meadows, Victoria S. and Quick, Lynnae C.}, year={2021}, month={Feb} }
 @article{byrne_blewett_chabot_hauck_mazarico_vander kaaden_vervack_oberst_hussmann_stark_2021, title={The case for landed Mercury science}, ISSN={["1572-9508"]}, DOI={10.1007/s10686-021-09788-8}, abstractNote={We advocate for establishing key scientific priorities for the future of Mercury exploration, including the development of specific science goals for a landed mission. We support the Mercury science community in fostering closer collaboration with ongoing and planned exoplanet investigations. The continued exploration of Mercury should be conceived as a multi-mission, multi-generational effort, and that the landed exploration of Mercury be a high scientific priority in the coming decade.}, journal={EXPERIMENTAL ASTRONOMY}, author={Byrne, Paul K. and Blewett, David T. and Chabot, Nancy L. and Hauck, Steven A. I. I. I. I. and Mazarico, Erwan and Vander Kaaden, Kathleen E. and Vervack, Ronald J. and Oberst, Jurgen and Hussmann, Hauke and Stark, Alexander}, year={2021}, month={Oct} }
 @article{detelich_byrne_dombard_schenk_2021, title={The morphology and age of the Iapetus equatorial ridge supports an exogenic origin}, volume={367}, ISSN={["1090-2643"]}, DOI={10.1016/j.icarus.2021.114559}, abstractNote={Both endogenic and exogenic formation mechanisms have been proposed for the equatorial ridge on Saturn's moon Iapetus. With photogeological mapping and crater statistics, we find that the morphology of the ridge is best explained by an exogenic origin, principally by the accretion onto the moon's surface of an orbiting ring of material.}, journal={ICARUS}, author={Detelich, Charlene E. and Byrne, Paul K. and Dombard, Andrew J. and Schenk, Paul M.}, year={2021}, month={Oct} }
 @article{izenberg_mcnutt_runyon_byrne_macdonald_2021, title={Venus Exploration in the New Human Spaceflight Age}, volume={180}, ISSN={["1879-2030"]}, DOI={10.1016/j.actaastro.2020.12.020}, abstractNote={An often-overlooked aspect of human missions to Mars is that the optimal path to the Red Planet could include a flyby of Venus. As part of so-called opposition missions, a crewed spacecraft would, after departing Earth, approach Venus en route to Mars. Such Venus flybys would offer unique opportunities to practice deep-space human operations during phases of flight for which a direct return to Earth would be a viable abort option. Indeed, crewed flyby missions to Venus provide a basis for longer-duration human spaceflight activities before committing to longer-duration and lower-launch-cadence missions solely to Mars. During Venus flybys, astronauts bound for Mars could carry out opportunistic “human-in-the-loop” scientific activities, such as controlling an aerial platform or directing in situ sampling by a landed spacecraft for much lower cost than a dedicated crewed mission to Venus. An independent crewed Venus flyby could also serve as a useful systems demonstration mission prior to a first human mission to Mars. With a renewed focus on landing humans on Mars in the 2030s and the formidable challenges still ahead for safe and successful long-duration human spaceflight, the time to consider incorporating Venus on the path to Mars is now.}, journal={ACTA ASTRONAUTICA}, author={Izenberg, Noam R. and McNutt, Ralph L., Jr. and Runyon, Kirby D. and Byrne, Paul K. and MacDonald, Alexander}, year={2021}, month={Mar}, pages={100–104} }
 @article{byrne_ghail_gilmore_sengor_klimczak_senske_whitten_khawja_ernst_solomon_2021, title={Venus tesserae feature layered, folded, and eroded rocks}, volume={49}, ISSN={["1943-2682"]}, DOI={10.1130/G47940.1}, abstractNote={1707. [12] Banks B. K. and Hansen V. L. (2000) JGR, 105, 17,655–17,667. [13] Ghent R. and Hansen V. L. (2005) Icarus, 139, 116–136. [14] Cofrade G. et al. (2019) Planet. Space Sci., 178, 104706. [15] Ford P. G. and Pettengill G. H. (1992) JGR, 97, 13,103–13,114. [16] Herrick R. R. et al. (2012) Eos, 93, 125–126. [17] Molinaro M. et al. (2005) Tectonics, 24, TC3007. [18] Li J. et al. (2016) JGR, 121, 3048–3080. [19] Ramsey J. G. (1967) Folding and Fracturing of Rocks. McGraw-Hill, New York. [20] Hansen V. L. and Willis J. J. (1996) Icarus, 123, 296–312. [21] Greeley R. et al. (1984) Icarus, 57, 112–124. [22] Craddock R. A. (2011) Prog. Phys. Geog., 36, 110–124. [23] Selivanov A. S. et al. (1982) Sov. Astron. Lett., 8, 235–236. [24] Carvalho F. P. et al. (2011) ICE J. Mar. Sci., 68, 427–435. [25] McKinnon W. B. et al. (1997) in Venus II (Bougher S. W. et al., eds.), Univ. Ariz. Press, pp. 969–1014. [26] Hansen V. L. et al. (1999) Geology, 27, 1071–1074. [27] Basilevsky A. T. et al. (1985) GSA Bull., 96, 137–144. [28] Ingersoll A. P. (1969) J. Atmos. Sci., 26, 1191–1198. Figure 2: (a) A set of lenticular landforms along the northern margin of Ovda Regio that we interpret as periclinal folds. The image is in orthographic projection, centered at 0.5°N, 80.5°E; Radar look direction is from the left. (b) Periclines in southeast Sichuan basin, China (arrows mark two examples). Image is in orthographic projection, centered at 30°N, 107°E. 2514.pdf 51st Lunar and Planetary Science Conference (2020)}, number={1}, journal={GEOLOGY}, author={Byrne, Paul K. and Ghail, Richard C. and Gilmore, Martha S. and Sengor, A. M. Celal and Klimczak, Christian and Senske, David A. and Whitten, Jennifer L. and Khawja, Sara and Ernst, Richard E. and Solomon, Sean C.}, year={2021}, month={Jan}, pages={81–85} }
 @article{byrne_2020, title={A comparison of inner Solar System volcanism}, volume={4}, ISSN={["2397-3366"]}, DOI={10.1038/s41550-019-0944-3}, number={4}, journal={NATURE ASTRONOMY}, author={Byrne, Paul K.}, year={2020}, month={Apr}, pages={321–327} }
 @article{kinczyk_prockter_byrne_susorney_chapman_2020, title={A morphological evaluation of crater degradation on Mercury: Revisiting crater classification with MESSENGER data}, volume={341}, ISSN={["1090-2643"]}, DOI={10.1016/j.icarus.2020.113637}, abstractNote={Observations of impact crater morphology can be used to gain insight into the geological history and evolution of a planet's surface. Image data from the Mariner 10 mission revealed the diversity of impact crater morphologies and degradational states on Mercury, leading to early studies that sought to establish a stratigraphic column for the planet, despite only acquiring image data for ~45% of the surface. In 2011, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered orbit around Mercury, returning a high-resolution global image dataset that enables a robust analysis of crater morphology and degradation to be completed for the entirety of Mercury's surface. In this study, we conducted a visual classification of crater degradation according to initial crater morphology, and assigned a degradation state to all craters on Mercury ≥40 km in diameter. In our scheme, Class 1 craters are those that are heavily degraded, and Class 5 craters are very fresh with bright ray systems. We discuss the processes involved in crater degradation and erasure, and the challenges associated with applying crater degradation to derive the timing of geological events. We found that, based on the global spatial density of craters in each class, there appears to be a dearth of Class 1 craters within the intercrater plains, likely due to several ancient basin-sized impacts effectively obliterating a considerable portion of craters ≥40 km in diameter in this region. The crater degradation database we present here will serve as a useful tool for future analyses of Mercury's geological evolution.}, journal={ICARUS}, author={Kinczyk, Mallory J. and Prockter, Louise M. and Byrne, Paul K. and Susorney, Hannah C. M. and Chapman, Clark R.}, year={2020}, month={May} }
 @article{peterson_johnson_byrne_phillips_2020, title={Fault Structure and Origin of Compressional Tectonic Features Within the Smooth Plains on Mercury}, volume={125}, ISSN={["2169-9100"]}, DOI={10.1029/2019JE006183}, abstractNote={The major physiographic “smooth plains” units on Mercury are dominantly composed of volcanic deposits that have been deformed by horizontal compressive stresses. An open issue is whether these features formed by stresses induced by global contraction, bending stresses due to volcanic loading, or some combination of both. In this study, we model the surface expression of 12 shortening structures within several smooth plains units across Mercury to determine the geometries of the underlying faults. We implement an elastic dislocation model, using both listric and planar fault geometries, to place estimates on the depth of faulting for each feature. We show that a majority of smooth plains shortening structures penetrate the lithosphere to depths greater than 15 km. Thrust faults of this scale have not previously been recognized within the planet's smooth plains units and require a large horizontal stresses to form, which is best explained if this stress arises from global contraction. Further, our results suggest that the observed relief and length contrast between features in the smooth plains units and older intercrater plains units can be explained by interior layering of, and/or a shallower brittle‐ductile transition underlying, the smooth plains units.}, number={7}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS}, author={Peterson, Georgia A. and Johnson, Catherine L. and Byrne, Paul K. and Phillips, Roger J.}, year={2020}, month={Jul} }
 @article{heap_gilg_byrne_wadsworth_reuschle_2020, title={Petrophysical properties, mechanical behaviour, and failure modes of impact melt-bearing breccia (suevite) from the Ries impact crater (Germany)}, volume={349}, ISSN={["1090-2643"]}, DOI={10.1016/j.icarus.2020.113873}, abstractNote={The physical properties and mechanical behaviour of impactites are an important parameter in fluid flow models and slope stability and landscape evolution assessments for heavily impacted planetary bodies. We first present porosity, permeability, Young's modulus, and uniaxial compressive strength measurements for three suevites from the Ries impact crater (Germany). Porosity ranges from 0.18 to 0.43, permeability from 5.8 × 10−16 to 5.1 × 10−14 m2, Young's modulus from 1.4 to 8.1 GPa, and uniaxial compressive strength from 7.3 to 48.6 MPa. To explore their mechanical behaviour, we performed triaxial deformation experiments on these samples at a range of confining pressures. The brittle–ductile transition for the lowest (0.25) and highest (0.38) porosity suevite samples was at a confining pressure of ~30 and ~10 MPa, respectively (corresponding to, for example, depths of ~1 and ~4 km on Mars, respectively). Microstructural observations show that the dominant deformation micromechanism during brittle deformation is microcracking, and during ductile deformation is distributed cataclastic pore collapse. We show that a theoretically grounded permeability model for welded granular media accurately captures the permeability of the studied suevites, and we use micromechanical models to glean insight as to their mechanical behaviour. Finally, we upscale our laboratory measurements to provide physical property values for length scales more relevant for large-scale models, and we compare these data with those for basalt (a lithology representative of the surface of the inner Solar System bodies). These analyses show how macroscopic fractures serve to increase the permeability and decrease the strength and Young's modulus of suevite and basalt. We also find, for example, that basalt can be a factor of 2–5 stronger than suevite in the shallow crust. Our study suggests, therefore, that the rock masses comprising older, bombarded crusts are substantially weaker and more porous and permeable than the younger plains material on these bodies. These findings should be considered in large-scale fluid flow modelling and when providing crustal strength estimates or slope stability assessments for planetary bodies on which protracted records of impact bombardment are preserved.}, journal={ICARUS}, author={Heap, Michael J. and Gilg, H. Albert and Byrne, Paul K. and Wadsworth, Fabian B. and Reuschle, Thierry}, year={2020}, month={Oct} }
 @misc{rothery_massironi_alemanno_barraud_besse_bott_brunetto_bunce_byrne_capaccioni_et al._2020, title={Rationale for BepiColombo Studies of Mercury's Surface and Composition}, volume={216}, ISSN={["1572-9672"]}, DOI={10.1007/s11214-020-00694-7}, abstractNote={Abstract BepiColombo has a larger and in many ways more capable suite of instruments relevant for determination of the topographic, physical, chemical and mineralogical properties of Mercury’s surface than the suite carried by NASA’s MESSENGER spacecraft. Moreover, BepiColombo’s data rate is substantially higher. This equips it to confirm, elaborate upon, and go beyond many of MESSENGER’s remarkable achievements. Furthermore, the geometry of BepiColombo’s orbital science campaign, beginning in 2026, will enable it to make uniformly resolved observations of both northern and southern hemispheres. This will offer more detailed and complete imaging and topographic mapping, element mapping with better sensitivity and improved spatial resolution, and totally new mineralogical mapping. We discuss MESSENGER data in the context of preparing for BepiColombo, and describe the contributions that we expect BepiColombo to make towards increased knowledge and understanding of Mercury’s surface and its composition. Much current work, including analysis of analogue materials, is directed towards better preparing ourselves to understand what BepiColombo might reveal. Some of MESSENGER’s more remarkable observations were obtained under unique or extreme conditions. BepiColombo should be able to confirm the validity of these observations and reveal the extent to which they are representative of the planet as a whole. It will also make new observations to clarify geological processes governing and reflecting crustal origin and evolution. We anticipate that the insights gained into Mercury’s geological history and its current space weathering environment will enable us to better understand the relationships of surface chemistry, morphologies and structures with the composition of crustal types, including the nature and mobility of volatile species. This will enable estimation of the composition of the mantle from which the crust was derived, and lead to tighter constraints on models for Mercury’s origin including the nature and original heliocentric distance of the material from which it formed.}, number={4}, journal={SPACE SCIENCE REVIEWS}, author={Rothery, David A. and Massironi, Matteo and Alemanno, Giulia and Barraud, Oceane and Besse, Sebastien and Bott, Nicolas and Brunetto, Rosario and Bunce, Emma and Byrne, Paul and Capaccioni, Fabrizio and et al.}, year={2020}, month={Jun} }
 @article{khawja_ernst_samson_byrne_ghail_maclellan_2020, title={Tesserae on Venus may preserve evidence of fluvial erosion}, volume={11}, ISBN={2041-1723}, DOI={10.1038/s41467-020-19336-1}, abstractNote={Fluvial erosion is usually assumed to be absent on Venus, precluded by a high surface temperature of ~450 °C and supported by extensive uneroded volcanic flows. However, recent global circulation models suggest the possibility of Earth-like climatic conditions on Venus for much of its earlier history, prior to catastrophic runaway greenhouse warming. We observe that the stratigraphically oldest, geologically most complex units, tesserae, exhibit valley patterns morphologically similar to the patterns resulting from fluvial erosion on Earth. Given poor topographic resolution, we use an indirect technique to recognize valleys, based on the pattern of lava flooding of tesserae margins by adjacent plains volcanism. These observed valley patterns are attributed to primary geology, tectonic deformation, followed by fluvial erosion (and lesser wind erosion). This proposed fluvial erosion in tesserae provides support for climate models for a cool, wet climate on early Venus and could be an attractive research theme for future Venus missions.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Khawja, S. and Ernst, R. E. and Samson, C. and Byrne, P. K. and Ghail, R. C. and MacLellan, L. M.}, year={2020} }
 @article{james_smith_byrne_kendall_melosh_zuber_2019, title={Deep Structure of the Lunar South Pole-Aitken Basin}, volume={46}, ISSN={["1944-8007"]}, DOI={10.1029/2019GL082252}, abstractNote={Abstract}, number={10}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={James, Peter B. and Smith, David E. and Byrne, Paul K. and Kendall, Jordan D. and Melosh, H. Jay and Zuber, Maria T.}, year={2019}, month={May}, pages={5100–5106} }
 @article{peterson_johnson_byrne_phillips_2019, title={Distribution of Areal Strain on Mercury: Insights Into the Interaction of Volcanism and Global Contraction}, volume={46}, ISSN={["1944-8007"]}, DOI={10.1029/2018GL080749}, abstractNote={Abstract}, number={2}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Peterson, Georgia A. and Johnson, Catherine L. and Byrne, Paul K. and Phillips, Roger J.}, year={2019}, month={Jan}, pages={608–615} }
 @article{klimczak_byrne_sengor_solomon_2019, title={Principles of structural geology on rocky planets}, volume={56}, ISSN={["1480-3313"]}, DOI={10.1139/cjes-2019-0065}, abstractNote={Although Earth is the only known planet on which plate tectonics operates, many small- and large-scale tectonic landforms indicate that deformational processes also occur on the other rocky planets. Although the mechanisms of deformation differ on Mercury, Venus, and Mars, the surface manifestations of their tectonics are frequently very similar to those found on Earth. Furthermore, tectonic processes invoked to explain deformation on Earth before the recognition of horizontal mobility of tectonic plates remain relevant for the other rocky planets. These connections highlight the importance of drawing analogies between the rocky planets for characterizing deformation of their lithospheres and for describing, applying appropriate nomenclature, and understanding the formation of their resulting tectonic structures. Here we characterize and compare the lithospheres of the rocky planets, describe structures of interest and where we study them, provide examples of how historic views on geology are applicable to planetary tectonics, and then apply these concepts to Mercury, Venus, and Mars.}, number={12}, journal={CANADIAN JOURNAL OF EARTH SCIENCES}, author={Klimczak, Christian and Byrne, Paul K. and Sengor, A. M. Celal and Solomon, Sean C.}, year={2019}, month={Dec}, pages={1437–1457} }
 @misc{vander kaaden_mccubbin_byrne_chabot_ernst_johnson_thompson_2019, title={Revolutionizing Our Understanding of the Solar System via Sample Return from Mercury}, volume={215}, ISSN={["1572-9672"]}, DOI={10.1007/s11214-019-0614-x}, number={8}, journal={SPACE SCIENCE REVIEWS}, author={Vander Kaaden, Kathleen E. and McCubbin, Francis M. and Byrne, Paul K. and Chabot, Nancy L. and Ernst, Carolyn M. and Johnson, Catherine L. and Thompson, Michelle S.}, year={2019}, month={Nov} }
 @article{solomon_byrne_2019, title={The Exploration of Mercury by Spacecraft}, volume={15}, ISSN={["1811-5217"]}, DOI={10.2138/gselements.15.1.15}, number={1}, journal={ELEMENTS}, author={Solomon, Sean C. and Byrne, Paul K.}, year={2019}, month={Feb}, pages={15–20} }
 @article{vries_byrne_delcamp_einarson_gogus_guilbaud_hagos_harangi_jerram_matenco_et al._2018, title={A global framework for the Earth: putting geological sciences in context}, volume={171}, ISSN={["1872-6364"]}, DOI={10.1016/j.gloplacha.2017.12.019}, abstractNote={We propose a global framework for the Earth system to facilitate communication between the geoscience community, the public and policy makers. Geoscience research aims to understand the history and evolution of the Earth system. This combines the non-living and living parts of the Earth, especially through interactions of the lithosphere, biosphere and atmosphere as well as the other parts of the system, such as the asthenosphere, core and extraterrestrial influences. Such research considers a system that spans scales from microscopic (micrometer scale) to megascopic (many 1000 s of km scale), and from milliseconds to millions of years. To connect different parts of this immense system, we habitually use a wide range of ad hoc geological frameworks, systems and geological environment models, where different processes and features operate and combine. In consequence, one way to judge the significance of our work, and to increase its value, is to assess how the elements studied are integrated within the whole Earth system. This allows us to see what implications any study has for this greater Earth system. To do this successfully, our research needs a standard global framework to assess a study's relevance. However, such a global framework does not formally exist, and so this article looks at existing examples and proposes one that can systematically place research into a global geological context. This proposed framework has the advantage of being useful for communicating geological processes to other disciplines, and can be used for any type of Earth (or planetary) environment. This framework is a fundamental tool for geoscience communication and for outreach, especially through geological heritage (geoheritage). Geoheritage concerns the valuing and protection of geoscience and geological sites, and is a vital tool for communicating geoscience. It can be used to communicate our knowledge of global change, providing, through landscapes and outcrops, a story that renders the concepts and advances of geoscience accessible. Like our basic research, the concept of geoheritage evolves as our understanding of the Earth progresses, and these dual changes can be explained with the global framework. Geoheritage is a global activity and it needs a global framework to put sites into context. A revision of the UNESCO geological thematic studies was called for by the World Heritage Committee in 2014 (decision: 38 COM 8B.11), and this can be done with the input from the full geoscience community using this global geological framework. Thus, for research, geoscience policy and for geoheritage, a global framework is now needed. The proposed framework can place any site in its geological environment, related to its lithospheric plate tectonic setting and its history. The framework has a solid-earth bias (lithosphere), but includes all other spheres, such as the biosphere and anthropogenic activity. Extraterrestrial influences, like solar variations and metorite impacts are included. The framework is phenomenological, due to the necessity of grouping the features that we see, but these phenomena provide evidence of processes that we cannot see. The basic format is a table, a sketch of the Earth and a system diagram, three complementary and most powerful ways of depicting a system. A timeline, or stratigraphic column can be included, to show the evolution of geological history, and the table can be used as a ‘game board’ where one site migrates across from one set of conditions to another over time. The global framework allows any research site, area or subject to be set in the Earth's system, in a way that gives it context, allows comparisons and provides significance. We suggest that it can be a template for an internationally accepted version used to consolidate the necessary geoscience – geoheritage link and promote outreach.}, journal={GLOBAL AND PLANETARY CHANGE}, author={Vries, Benjamin van Wyk and Byrne, Paul and Delcamp, Audray and Einarson, Pall and Gogus, Oguz and Guilbaud, Marie-Noelle and Hagos, Miruts and Harangi, Szabolcs and Jerram, Dougal and Matenco, Liviu and et al.}, year={2018}, month={Dec}, pages={293–321} }
 @misc{lopes_gregg_harris_radebaugh_byrne_kerber_mouginis-mark_2018, title={Extraterrestrial lava lakes}, volume={366}, ISSN={["1872-6097"]}, DOI={10.1016/j.jvolgeores.2018.09.010}, abstractNote={Active lava lakes are rare on Earth, with only ten documented examples, all formed by lavas of basaltic composition and housed inside summit craters or calderas. The existence of lava lakes on other planetary bodies may imply similarities in either composition or volcano-tectonic settings, and so has important implications for understanding the link between melt production and volcanism. We review lava lakes on Earth and other planets, particularly active caldera-like features interpreted to be currently containing active lava lakes on Jupiter's moon Io, and features interpreted as remnants of lava lakes on Venus and Mars. Mercury and the Moon do not boast the major calderas or shield volcanoes of their larger rocky neighbors, partly due to a horizontally compressive tectonic regime arising from global contraction that makes it difficult to move melts through the upper crust. We discuss the evidence for active lava lakes on Io and show how modeling based on terrestrial lava lakes can reveal how these phenomena differ on both bodies; the superficial similarities do not necessarily imply that the plumbing is similar. Observations of the largest lava lake on Io, Loki Patera, provide insight into the nature of Ionian lava lakes in general, which may be more similar to eruptive episodes on the East Pacific Rise on Earth, which lead to temporary lava lakes. Although temporal data for Io's lava lake activity are scarce, studies of temporal variability of lava lakes on Earth are useful for providing ground truth for comparisons. Future studies of Earth by remote sensing and field observations, and of Io by both ground-based observations and future missions, are needed to answer many questions, including why lava lakes, rare on Earth, appear to be common on Io.}, journal={JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH}, author={Lopes, Rosaly M. C. and Gregg, Tracy K. P. and Harris, Andrew and Radebaugh, Jani and Byrne, Paul and Kerber, Laura and Mouginis-Mark, Peter}, year={2018}, month={Oct}, pages={74–95} }
 @article{byrne_2018, title={Mercury: the incredible shrinking planet}, volume={59}, ISSN={["1468-4004"]}, DOI={10.1093/astrogeo/aty024}, number={1}, journal={ASTRONOMY & GEOPHYSICS}, author={Byrne, Paul K.}, year={2018}, month={Feb}, pages={14–19} }
 @article{klimczak_crane_habermann_byrne_2018, title={The spatial distribution of Mercury's pyroclastic activity and the relation to lithospheric weaknesses}, volume={315}, ISSN={["1090-2643"]}, DOI={10.1016/j.icarus.2018.06.020}, abstractNote={Mercury's surface preserves a rich history of volcanism, impact cratering, and tectonic deformation. Geological observations show that the earliest evidence of thrust faulting that was induced by the secular cooling and resulting global contraction of the planet coincided with the waning stages of effusive volcanism, but that explosive volcanism continued beyond this point. Stresses from global contraction, however, would have precluded efficient vertical magma ascent. Sites of pyroclastic activity—manifest as irregular depressions surrounded by diffuse, spectrally distinct halos—spatially coincide with lithospheric discontinuities, such as faults or those associated with impact craters. The vast majority of explosive vents are situated on the floors, rims, central peaks, or peak rings of impact structures. A substantial portion of such vents is also proximal to thrust faults: they are most spatially concentrated at or within 20 km of faults, with ever fewer vents progressively farther from tectonic structures. We statistically evaluated the spatial distribution of sites of pyroclastic activity with respect to faults and impact craters by generating sets of random point locations of equal count to those volcanic sites, computing their spatial relationship to the mapped faults and craters, and comparing them to our observations. We find that although the observed proximity of vents to faults is indistinguishable from a random distribution, their spatial association with impact craters is non-random. To examine the interrelatedness of several geospatial relationships of lithospheric weaknesses and pyroclastic activity, we performed a principal component analysis that tested correlations between vent size, the presence of vents within a crater, the diameters and degradation states of those craters, and vent distance from mapped faults, which help tie together interpretations of magma volumes and eruption energies, repeated utilization of magma pathways, and durations of eruptive events in the geological context of global contraction. Results reveal a predominance of small-sized vents indicative of short-lived, low-volume pyroclastic activity that are consistent with suppressed volcanism after the onset of global contraction. Greater size ranges of vents are found in large impact craters and when faults are nearby, which points to denser fracture networks facilitating magma ascent.}, journal={ICARUS}, author={Klimczak, Christian and Crane, Kelsey T. and Habermann, Mya A. and Byrne, Paul K.}, year={2018}, month={Nov}, pages={115–123} }
 @article{klimczak_kling_byrne_2018, title={Topographic Expressions of Large Thrust Faults on Mars}, volume={123}, ISSN={["2169-9100"]}, DOI={10.1029/2017JE005448}, abstractNote={Abstract}, number={8}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS}, author={Klimczak, Christian and Kling, Corbin L. and Byrne, Paul K.}, year={2018}, month={Aug}, pages={1973–1995} }
 @article{heap_byrne_mikhail_2017, title={Low surface gravitational acceleration of Mars results in a thick and weak lithosphere: Implications for topography, volcanism, and hydrology}, volume={281}, ISSN={["1090-2643"]}, DOI={10.1016/j.icarus.2016.09.003}, abstractNote={Surface gravitational acceleration (surface gravity) on Mars, the second-smallest planet in the Solar System, is much lower than that on Earth. A direct consequence of this low surface gravity is that lithostatic pressure is lower on Mars than on Earth at any given depth. Collated published data from deformation experiments on basalts suggest that, throughout its geological history (and thus thermal evolution), the Martian brittle lithosphere was much thicker but weaker than that of present-day Earth as a function solely of surface gravity. We also demonstrate, again as a consequence of its lower surface gravity, that the Martian lithosphere is more porous, that fractures on Mars remain open to greater depths and are wider at a given depth, and that the maximum penetration depth for opening-mode fractures (i.e., joints) is much deeper on Mars than on Earth. The result of a weak Martian lithosphere is that dykes—the primary mechanism for magma transport on both planets—can propagate more easily and can be much wider on Mars than on Earth. We suggest that this increased the efficiency of magma delivery to and towards the Martian surface during its volcanically active past, and therefore assisted the exogeneous and endogenous growth of the planet's enormous volcanoes (the heights of which are supported by the thick Martian lithosphere) as well as extensive flood-mode volcanism. The porous and pervasively fractured (and permeable) nature of the Martian lithosphere will have also greatly assisted the subsurface storage of and transport of fluids through the lithosphere throughout its geologically history. And so it is that surface gravity, influenced by the mass of a planetary body, can greatly modify the mechanical and hydraulic behaviour of its lithosphere with manifest differences in surface topography and geomorphology, volcanic character, and hydrology.}, journal={ICARUS}, author={Heap, Michael J. and Byrne, Paul K. and Mikhail, Sami}, year={2017}, month={Jan}, pages={103–114} }
 @article{susorney_barnouin_ernst_byrne_2017, title={The surface roughness of Mercury from the Mercury Laser Altimeter: Investigating the effects of volcanism, tectonism, and impact cratering}, volume={122}, ISSN={["2169-9100"]}, DOI={10.1002/2016je005228}, abstractNote={Abstract}, number={6}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS}, author={Susorney, H. C. M. and Barnouin, O. S. and Ernst, C. M. and Byrne, P. K.}, year={2017}, month={Jun}, pages={1372–1390} }
 @article{byrne_ostrach_fassett_chapman_denevi_evans_klimczak_banks_head_solomon_2016, title={Widespread effusive volcanism on Mercury likely ended by about 3.5Ga}, volume={43}, ISSN={["1944-8007"]}, DOI={10.1002/2016gl069412}, abstractNote={Abstract}, number={14}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Byrne, Paul K. and Ostrach, Lillian R. and Fassett, Caleb I. and Chapman, Clark R. and Denevi, Brett W. and Evans, Alexander J. and Klimczak, Christian and Banks, Maria E. and Head, James W. and Solomon, Sean C.}, year={2016}, month={Jul}, pages={7408–7416} }
 @article{klimczak_byrne_solomon_2015, title={A rock-mechanical assessment of Mercury's global tectonic fabric}, volume={416}, ISSN={0012-821X}, url={http://dx.doi.org/10.1016/J.EPSL.2015.02.003}, DOI={10.1016/J.EPSL.2015.02.003}, abstractNote={Mercury's global tectonic history is thought to have been dominated by two major processes: tidal despinning and global contraction. Each process is expected to have produced a distinctive global stress field and resultant fault pattern. Thousands of thrust-fault-related landforms documented on Mercury can be attributed to global contraction, but no global signature of tidal despinning has been conclusively documented. Because global contraction operated throughout an extended portion of Mercury's geologic history, any tidal despinning pattern either would have formed together with global contraction, or would have been modified by global contraction after despinning was complete. Here, we reassess global fracture patterns predicted to result from tidal despinning and from a combination of tidal despinning and global contraction. We specifically make use of rock strength and deformability parameters appropriate for Mercury's fractured lithosphere. Results indicate that a tidal despinning pattern would consist only of a global set of opening-mode fractures (joints) in the upper part of the lithosphere, whereas the combination of tidal despinning and global contraction would have produced a global population of thrust faults, with no preferred orientations in the polar regions but with an increasing preference for north–south orientations toward the equator. If an equatorial bulge from an early state of rapid spin was supported by Mercury's lithosphere, two end-member scenarios for the timing and duration of these two processes may be considered. In one, tidal despinning predated global contraction; in the other, tidal despinning and global contraction overlapped in time. We test the predictions of both scenarios against the distribution and orientations of Mercury's tectonic landforms. The global pattern of thrust faults is generally consistent with predictions for the scenario under which tidal despinning and global contraction temporally overlapped.}, journal={Earth and Planetary Science Letters}, publisher={Elsevier BV}, author={Klimczak, Christian and Byrne, Paul K. and Solomon, Sean C.}, year={2015}, month={Apr}, pages={82–90} }
 @article{byrne_klimczak_mcgovern_mazarico_james_neumann_zuber_solomon_2015, title={Deep-seated thrust faults bound the Mare Crisium lunar mascon}, volume={427}, ISSN={0012-821X}, url={http://dx.doi.org/10.1016/J.EPSL.2015.06.022}, DOI={10.1016/J.EPSL.2015.06.022}, abstractNote={Mare Crisium is composed of a set of volcanic deposits situated in an impact basin on the Moon's near side. The topography of the mare is dominated by an annulus of elevated topography, the inner edge of which is delineated by basin-concentric wrinkle ridges. From a combination of remotely sensed image and topographic data and numerical modeling, we show that the thrust faults that underlie these ridges penetrate up to 20 km in depth, considerably below the base of the mare deposits themselves. Thrust faults of this scale have not heretofore been recognized on the Moon. Mare Crisium sits above a region of uplifted mantle, which contributes to a mass excess beneath the basin, and we demonstrate by comparison with free-air gravity anomaly and derived crustal thickness data for Crisium that the thrust faults structurally bound this elevated mantle material. By means of finite-element models of stresses induced by lithospheric loading within the basin, we argue that the deep-seated thrusts may have been localized by the boundary between the superisostatic mantle material and a sub-isostatic collar of thickened crust that resulted from basin formation and modification shortly after impact. Importantly, numerous other mare-filled mascon basins on the Moon share the same topographic and tectonic characteristics as Crisium, suggesting that they, too, are underlain by deep-seated thrust faults that formed in a similar manner.}, journal={Earth and Planetary Science Letters}, publisher={Elsevier BV}, author={Byrne, Paul K. and Klimczak, Christian and McGovern, Patrick J. and Mazarico, Erwan and James, Peter B. and Neumann, Gregory A. and Zuber, Maria T. and Solomon, Sean C.}, year={2015}, month={Oct}, pages={183–190} }
 @article{byrne_zhang_ullah_binley_heathwaite_heppell_lansdown_trimmer_2015, title={Diffusive equilibrium in thin films provides evidence of suppression of hyporheic exchange and large-scale nitrate transformation in a groundwater-fed river}, volume={29}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/HYP.10269}, DOI={10.1002/HYP.10269}, abstractNote={The hyporheic zone of riverbed sediments has the potential to attenuate nitrate from upwelling, polluted groundwater. However, the coarse‐scale (5–10 cm) measurement of nitrogen biogeochemistry in the hyporheic zone can often mask fine‐scale (<1 cm) biogeochemical patterns, especially in near‐surface sediments, leading to incomplete or inaccurate representation of the capacity of the hyporheic zone to transform upwelling NO3−. In this study, we utilised diffusive equilibrium in thin‐films samplers to capture high resolution (cm‐scale) vertical concentration profiles of NO3−, SO42−, Fe and Mn in the upper 15 cm of armoured and permeable riverbed sediments. The goal was to test whether nitrate attenuation was occurring in a sub‐reach characterised by strong vertical (upwelling) water fluxes. The vertical concentration profiles obtained from diffusive equilibrium in thin‐films samplers indicate considerable cm‐scale variability in NO3− (4.4 ± 2.9 mg N/L), SO42− (9.9 ± 3.1 mg/l) and dissolved Fe (1.6 ± 2.1 mg/l) and Mn (0.2 ± 0.2 mg/l). However, the overall trend suggests the absence of substantial net chemical transformations and surface‐subsurface water mixing in the shallow sediments of our sub‐reach under baseflow conditions. The significance of this is that upwelling NO3−‐rich groundwater does not appear to be attenuated in the riverbed sediments at <15 cm depth as might occur where hyporheic exchange flows deliver organic matter to the sediments for metabolic processes. It would appear that the chemical patterns observed in the shallow sediments of our sub‐reach are not controlled exclusively by redox processes and/or hyporheic exchange flows. Deeper‐seated groundwater fluxes and hydro‐stratigraphy may be additional important drivers of chemical patterns in the shallow sediments of our study sub‐reach. © 2015 The Authors. Hydrological Processes Published by John Wiley & Sons Ltd.}, number={6}, journal={Hydrological Processes}, publisher={Wiley}, author={Byrne, P. and Zhang, H. and Ullah, S. and Binley, A. and Heathwaite, A.L. and Heppell, C.M. and Lansdown, K. and Trimmer, M.}, year={2015}, month={Mar}, pages={1385–1396} }
 @article{banks_xiao_watters_strom_braden_chapman_solomon_klimczak_byrne_2015, title={Duration of activity on lobate-scarp thrust faults on Mercury}, volume={120}, ISSN={2169-9097}, url={http://dx.doi.org/10.1002/2015JE004828}, DOI={10.1002/2015JE004828}, abstractNote={Lobate scarps, landforms interpreted as the surface manifestation of thrust faults, are widely distributed across Mercury and preserve a record of its history of crustal deformation. Their formation is primarily attributed to the accommodation of horizontal shortening of Mercury's lithosphere in response to cooling and contraction of the planet's interior. Analyses of images acquired by the Mariner 10 and MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft during flybys of Mercury showed that thrust faults were active at least as far back in time as near the end of emplacement of the largest expanses of smooth plains. However, the full temporal extent of thrust fault activity on Mercury, particularly the duration of this activity following smooth plains emplacement, remained poorly constrained. Orbital images from the MESSENGER spacecraft reveal previously unrecognized stratigraphic relations between lobate scarps and impact craters of differing ages and degradation states. Analysis of these stratigraphic relations indicates that contraction has been a widespread and long‐lived process on the surface of Mercury. Thrust fault activity had initiated by a time near the end of the late heavy bombardment of the inner solar system and continued through much or all of Mercury's subsequent history. Such deformation likely resulted from the continuing secular cooling of Mercury's interior.}, number={11}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Banks, Maria E. and Xiao, Zhiyong and Watters, Thomas R. and Strom, Robert G. and Braden, Sarah E. and Chapman, Clark R. and Solomon, Sean C. and Klimczak, Christian and Byrne, Paul K.}, year={2015}, month={Nov}, pages={1751–1762} }
 @article{weider_nittler_starr_crapster-pregont_peplowski_denevi_head_byrne_hauck_ebel_et al._2015, title={Evidence for geochemical terranes on Mercury: Global mapping of major elements with MESSENGER's X-Ray Spectrometer}, volume={416}, ISSN={0012-821X}, url={http://dx.doi.org/10.1016/J.EPSL.2015.01.023}, DOI={10.1016/J.EPSL.2015.01.023}, abstractNote={We have mapped the major-element composition of Mercury's surface from orbital MESSENGER X-Ray Spectrometer measurements. These maps constitute the first global-scale survey of the surface composition of a Solar System body conducted with the technique of planetary X-ray fluorescence. Full maps of Mg and Al, together with partial maps of S, Ca, and Fe, each relative to Si, reveal highly variable compositions (e.g., Mg/Si and Al/Si range over 0.1–0.8 and 0.1–0.4, respectively). The geochemical variations that we observe are consistent with those inferred from other MESSENGER geochemical remote sensing datasets, but they do not correlate well with units mapped previously from spectral reflectance or morphology. Location-dependent, rather than temporally evolving, partial melt sources were likely the major influence on the compositions of the magmas that produced different geochemical terranes. A large (>5×106 km2) region with the highest Mg/Si, Ca/Si, and S/Si ratios, as well as relatively thin crust, may be the site of an ancient and heavily degraded impact basin. The distinctive geochemical signature of this region could be the consequence of high-degree partial melting of a reservoir in a vertically heterogeneous mantle that was sampled primarily as a result of the impact event.}, journal={Earth and Planetary Science Letters}, publisher={Elsevier BV}, author={Weider, Shoshana Z. and Nittler, Larry R. and Starr, Richard D. and Crapster-Pregont, Ellen J. and Peplowski, Patrick N. and Denevi, Brett W. and Head, James W. and Byrne, Paul K. and Hauck, Steven A., II and Ebel, Denton S. and et al.}, year={2015}, month={Apr}, pages={109–120} }
 @article{lansdown_heppell_trimmer_binley_heathwaite_byrne_zhang_2015, title={The interplay between transport and reaction rates as controls on nitrate attenuation in permeable, streambed sediments}, volume={120}, ISSN={2169-8953}, url={http://dx.doi.org/10.1002/2014JG002874}, DOI={10.1002/2014JG002874}, abstractNote={Anthropogenic nitrogen fixation and subsequent use of this nitrogen as fertilizer have greatly disturbed the global nitrogen cycle. Rivers are recognized hot spots of nitrogen removal in the landscape as interaction between surface water and sediments creates heterogeneous redox environments conducive for nitrogen transformations. Our understanding of riverbed nitrogen dynamics to date comes mainly from shallow sediments or hyporheic exchange flow pathways with comparatively little attention paid to groundwater‐fed, gaining reaches. We have used 15N techniques to quantify in situ rates of nitrate removal to 1 m depth within a groundwater‐fed riverbed where subsurface hydrology ranged from strong upwelling to predominantly horizontal water fluxes. We combine these rates with detailed hydrologic measurements to investigate the interplay between biogeochemical activity and water transport in controlling nitrogen attenuation along upwelling flow pathways. Nitrate attenuation occurred via denitrification rather than dissimilatory nitrate reduction to ammonium or anammox (range = 12 to >17,000 nmol 15N L−1 h−1). Overall, nitrate removal within the upwelling groundwater was controlled by water flux rather than reaction rate (i.e., Damköhler numbers <1) with the exception of two hot spots of biogeochemical activity. Deep sediments were as important a nitrate sink as shallow sediments with fast rates of denitrification and short water residence time close to the riverbed surface balanced by slower rates of denitrification and water flux at depth. Within this permeable riverbed >80% of nitrate removal occurs within sediments not exposed to hyporheic exchange flows under base flow conditions, illustrating the importance of deep sediments as nitrate sinks in upwelling systems.}, number={6}, journal={Journal of Geophysical Research: Biogeosciences}, publisher={American Geophysical Union (AGU)}, author={Lansdown, K. and Heppell, C. M. and Trimmer, M. and Binley, A. and Heathwaite, A. L. and Byrne, P. and Zhang, H.}, year={2015}, month={Jun}, pages={1093–1109} }
 @article{byrne_binley_heathwaite_ullah_heppell_lansdown_zhang_trimmer_keenan_2014, title={Control of river stage on the reactive chemistry of the hyporheic zone}, volume={28}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/HYP.9981}, DOI={10.1002/HYP.9981}, abstractNote={We examined the influence of river stage on subsurface hydrology and pore water chemistry within the hyporheic zone of a groundwater‐fed river during the summer baseflow period of 2011. We found river stage and geomorphologic environment to control chemical patterns in the hyporheic zone. At a high river stage, the flux of upwelling water in the shallow sediments (>20 cm) decreased at sample sites in the upper section of our study reach and increased substantially at sites in the lower section. This differential response is attributed to the contrasting geomorphology of these subreaches that affects the rate of the rise and fall of a river stage relative to the subsurface head. At sites where streamward vertical flux decreased, concentration profiles of a conservative environmental tracer suggest surface water infiltration into the riverbed below depths recorded at a low river stage. An increase in vertical flux at sites in the lower subreach is attributed to the movement of lateral subsurface waters originating from the adjacent floodplain. This lateral‐moving water preserved or decreased the vertical extent of the hyporheic mixing zone observed at a low river stage. Downwelling surface water appeared to be responsible for elevated dissolved organic carbon (DOC) and manganese (Mn) concentrations in shallow sediments (0–20 cm); however, lateral subsurface flows were probably important for elevated concentrations of these solutes at deeper levels. Results suggest that DOC delivered to hyporheic sediments during a high river stage from surface water and lateral subsurface sources could enhance heterotrophic microbial activities. Copyright © 2013 John Wiley & Sons, Ltd.}, number={17}, journal={Hydrological Processes}, publisher={Wiley}, author={Byrne, P. and Binley, A. and Heathwaite, A. L. and Ullah, S. and Heppell, C. M. and Lansdown, K. and Zhang, H. and Trimmer, M. and Keenan, P.}, year={2014}, month={Aug}, pages={4766–4779} }
 @article{byrne_klimczak_celâl şengör_solomon_watters_hauck, ii_2014, title={Mercury’s global contraction much greater than earlier estimates}, volume={7}, ISSN={1752-0894 1752-0908}, url={http://dx.doi.org/10.1038/NGEO2097}, DOI={10.1038/NGEO2097}, number={4}, journal={Nature Geoscience}, publisher={Springer Science and Business Media LLC}, author={Byrne, Paul K. and Klimczak, Christian and Celâl Şengör, A. M. and Solomon, Sean C. and Watters, Thomas R. and Hauck, II, Steven A.}, year={2014}, month={Mar}, pages={301–307} }
 @article{byrne_klimczak_williams_hurwitz_solomon_head_preusker_oberst_2013, title={An assemblage of lava flow features on Mercury}, volume={118}, ISSN={2169-9097}, url={http://dx.doi.org/10.1002/JGRE.20052}, DOI={10.1002/JGRE.20052}, abstractNote={In contrast to other terrestrial planets, Mercury does not possess a great variety of volcanic features, its history of volcanism instead largely manifest by expansive smooth plains. However, a set of landforms at high northern latitudes on Mercury resembles surface flow features documented on Earth, the Moon, Mars, and Venus. The most striking of such landforms are broad channels that host streamlined islands and that cut through the surrounding intercrater plains. Together with narrower, more sinuous channels, coalesced depressions, evidence for local flooding of intercrater plains by lavas, and a first‐order analysis of lava flow rates, the broad channels define an assemblage of flow features formed by the overland flow of, and erosion by, voluminous, high‐temperature, low‐viscosity lavas. This interpretation is consistent with compositional data suggesting that substantial portions of Mercury's crust are composed of magnesian, iron‐poor lithologies. Moreover, the proximity of this partially flooded assemblage to extensive volcanic plains raises the possibility that the formation of these flow features may preface total inundation of an area by lavas emplaced in a flood mode and that they escaped complete burial only due to a waning magmatic supply. Finally, that these broad channels on Mercury are volcanic in nature yet resemble outflow channels on Mars, which are commonly attributed to catastrophic water floods, implies that aqueous activity is not a prerequisite for the formation of such distinctive landforms on any planetary body.}, number={6}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Byrne, Paul K. and Klimczak, Christian and Williams, David A. and Hurwitz, Debra M. and Solomon, Sean C. and Head, James W. and Preusker, Frank and Oberst, Jürgen}, year={2013}, month={Jun}, pages={1303–1322} }
 @article{xiao_strom_blewett_byrne_solomon_murchie_sprague_domingue_helbert_2013, title={Dark spots on Mercury: A distinctive low-reflectance material and its relation to hollows}, volume={118}, ISSN={2169-9097}, url={http://dx.doi.org/10.1002/JGRE.20115}, DOI={10.1002/JGRE.20115}, abstractNote={Orbital images acquired by the MErcury, Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft reveal a distinctive low‐reflectance material on the surface of Mercury. Such material occurs in small, isolated, and thin surficial units. We term these features “dark spots.” Dark spots have the lowest average reflectance yet documented on the planet. In every case observed at sufficiently high resolution, dark spots feature hollows at their centers. Not all hollows, however, are surrounded by a dark spot. Dark spots have been found on low‐reflectance smooth plains, intercrater plains, heavily cratered terrain, and impact craters at almost all longitudes on Mercury, but they have not been documented on high‐reflectance smooth plains material. Dark spots are one of the youngest endogenic features on Mercury, and some postdate craters with distinctive rays. Sulfides may be the phase responsible for the low albedo of dark spot material. We propose that dark spots form during the initial stages of hollow formation, perhaps in a manner similar to intense outgassing events that feature exit velocities in excess of 100 m/s. Such outgassing could contemporaneously produce a depression that constitutes an embryonic hollow. Under this scenario, dark spot material is subsequently removed or modified by regolith gardening or other surface processes on time scales shorter than the lifetime of the central hollow.}, number={9}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Xiao, Zhiyong and Strom, Robert G. and Blewett, David T. and Byrne, Paul K. and Solomon, Sean C. and Murchie, Scott L. and Sprague, Ann L. and Domingue, Deborah L. and Helbert, Jörn}, year={2013}, month={Sep}, pages={1752–1765} }
 @article{klimczak_ernst_byrne_solomon_watters_murchie_preusker_balcerski_2013, title={Insights into the subsurface structure of the Caloris basin, Mercury, from assessments of mechanical layering and changes in long-wavelength topography}, volume={118}, ISSN={2169-9097}, url={http://dx.doi.org/10.1002/JGRE.20157}, DOI={10.1002/JGRE.20157}, abstractNote={The volcanic plains that fill the Caloris basin, the largest recognized impact basin on Mercury, are deformed by many graben and wrinkle ridges, among which the multitude of radial graben of Pantheon Fossae allow us to resolve variations in the depth extent of associated faulting. Displacement profiles and displacement‐to‐length scaling both indicate that faults near the basin center are confined to a ~ 4‐km‐thick mechanical layer, whereas faults far from the center penetrate more deeply. The fault scaling also indicates that the graben formed in mechanically strong material, which we identify with dry basalt‐like plains. These plains were also affected by changes in long‐wavelength topography, including undulations with wavelengths of up to 1300 km and amplitudes of 2.5 to 3 km. Geographic correlation of the depth extent of faulting with topographic variations allows a first‐order interpretation of the subsurface structure and mechanical stratigraphy in the basin. Further, crosscutting and superposition relationships among plains, faults, craters, and topography indicate that development of long‐wavelength topographic variations followed plains emplacement, faulting, and much of the cratering within the Caloris basin. As several examples of these topographic undulations are also found outside the basin, our results on the scale, structural style, and relative timing of the topographic changes have regional applicability and may be the surface expression of global‐scale interior processes on Mercury.}, number={10}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Klimczak, Christian and Ernst, Carolyn M. and Byrne, Paul K. and Solomon, Sean C. and Watters, Thomas R. and Murchie, Scott L. and Preusker, Frank and Balcerski, Jeffrey A.}, year={2013}, month={Oct}, pages={2030–2044} }
 @article{hurwitz_head_byrne_xiao_solomon_zuber_smith_neumann_2013, title={Investigating the origin of candidate lava channels on Mercury with MESSENGER data: Theory and observations}, volume={118}, ISSN={2169-9097}, url={http://dx.doi.org/10.1029/2012JE004103}, DOI={10.1029/2012JE004103}, abstractNote={Volcanic plains identified on Mercury are morphologically similar to lunar mare plains but lack constructional and erosional features that are prevalent on other terrestrial planetary bodies. We analyzed images acquired by the MESSENGER spacecraft to identify features on Mercury that may have formed by lava erosion. We used analytical models to estimate eruption flux, erosion rate, and eruption duration to characterize the formation of candidate erosional features, and we compared results with analyses of similar features observed on Earth, the Moon, and Mars. Results suggest that lava erupting at high effusion rates similar to those required to form the Teepee Butte Member of the Columbia River flood basalts (0.1–1.2 × 106 m3 s–1) would have been necessary to form wide valleys (>15 km wide) observed in Mercury's northern hemisphere, first by mechanical erosion to remove an upper regolith layer, then by thermal erosion once a lower rigid layer was encountered. Alternatively, results suggest that lava erupting at lower effusion rates similar to those predicted to have formed Rima Prinz on the Moon (4400 m3 s–1) would have been required to form, via thermal erosion, narrower channels (<7 km wide) observed on Mercury. Although these results indicate how erosion might have occurred on Mercury, the observed features may have formed by other processes, including lava flooding terrain sculpted during the formation of the Caloris basin in the case of the wide valleys, or impact melt carving channels into impact ejecta in the case of the narrower channels.}, number={3}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Hurwitz, Debra M. and Head, James W. and Byrne, Paul K. and Xiao, Zhiyong and Solomon, Sean C. and Zuber, Maria T. and Smith, David E. and Neumann, Gregory A.}, year={2013}, month={Mar}, pages={471–486} }
 @article{denevi_ernst_meyer_robinson_murchie_whitten_head_watters_solomon_ostrach_et al._2013, title={The distribution and origin of smooth plains on Mercury}, volume={118}, ISSN={2169-9097}, url={http://dx.doi.org/10.1002/JGRE.20075}, DOI={10.1002/JGRE.20075}, abstractNote={Orbital images from the MESSENGER spacecraft show that ~27% of Mercury's surface is covered by smooth plains, the majority (>65%) of which are interpreted to be volcanic in origin. Most smooth plains share the spectral characteristics of Mercury's northern smooth plains, suggesting they also share their magnesian alkali‐basalt‐like composition. A smaller fraction of smooth plains interpreted to be volcanic in nature have a lower reflectance and shallower spectral slope, suggesting more ultramafic compositions, an inference that implies high temperatures and high degrees of partial melting in magma source regions persisted through most of the duration of smooth plains formation. The knobby and hummocky plains surrounding the Caloris basin, known as Odin‐type plains, occupy an additional 2% of Mercury's surface. The morphology of these plains and their color and stratigraphic relationships suggest that they formed as Caloris ejecta, although such an origin is in conflict with a straightforward interpretation of crater size–frequency distributions. If some fraction is volcanic, this added area would substantially increase the abundance of relatively young effusive deposits inferred to have more mafic compositions. Smooth plains are widespread on Mercury, but they are more heavily concentrated in the north and in the hemisphere surrounding Caloris. No simple relationship between plains distribution and crustal thickness or radioactive element distribution is observed. A likely volcanic origin for some older terrain on Mercury suggests that the uneven distribution of smooth plains may indicate differences in the emplacement age of large‐scale volcanic deposits rather than differences in crustal formational process.}, number={5}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Denevi, Brett W. and Ernst, Carolyn M. and Meyer, Heather M. and Robinson, Mark S. and Murchie, Scott L. and Whitten, Jennifer L. and Head, James W. and Watters, Thomas R. and Solomon, Sean C. and Ostrach, Lillian R. and et al.}, year={2013}, month={May}, pages={891–907} }
 @article{blair_freed_byrne_klimczak_prockter_ernst_solomon_melosh_zuber_2013, title={The origin of graben and ridges in Rachmaninoff, Raditladi, and Mozart basins, Mercury}, volume={118}, ISSN={2169-9097}, url={http://dx.doi.org/10.1029/2012JE004198}, DOI={10.1029/2012JE004198}, abstractNote={The Rachmaninoff, Raditladi, and Mozart peak‐ring impact basins on Mercury display a distinctive pattern of tectonic features consisting of a central zone that is either devoid of tectonic landforms or contains small ridges, a medial annulus of prominent and predominantly circumferentially oriented graben, and a distal zone displaying graben that occur in a mix of orientations and that are less evident toward the peak ring. Here we use finite element models to explore three candidate scenarios for the formation of these tectonic features: (1) thermal contraction of the interior smooth plains, (2) isostatic uplift of the basin floor, and (3) subsidence following volcanic loading. Our results suggest that only thermal contraction can account for the observed pattern of graben, whereas some combination of subsidence and global contraction is the most likely explanation for the central ridges in Rachmaninoff and Mozart. Thermal contraction models, however, predict the formation of graben in the centermost region of each basin, where no graben are observed. We hypothesize that graben in this region were buried by a thin, late‐stage flow of plains material, and images of partially filled graben provide evidence of such late‐stage plains emplacement. These results suggest that the smooth plains units in these three basins are volcanic in origin. The thermal contraction models also imply a cooling unit ~1 km thick near the basin center, further supporting the view that plains‐forming lavas on Mercury were often of sufficiently high volume and low viscosity to pool to substantial thicknesses within basins and craters.}, number={1}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Blair, David M. and Freed, Andrew M. and Byrne, Paul K. and Klimczak, Christian and Prockter, Louise M. and Ernst, Carolyn M. and Solomon, Sean C. and Melosh, H. Jay and Zuber, Maria T.}, year={2013}, month={Jan}, pages={47–58} }
 @article{byrne_van wyk de vries_murray_troll_2012, title={A volcanotectonic survey of Ascraeus Mons, Mars}, volume={117}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2011JE003825}, DOI={10.1029/2011JE003825}, abstractNote={[1] Ascraeus Mons is one of the largest volcanoes on Mars. It is replete with well-preserved features that can be used to understand its volcanotectonic evolution. Previous studies of this volcano focused on specific features, and were limited by the quality and coverage of contemporary data. Our objective is to review and enhance the existing developmental model for Ascraeus by considering all endogenic surface features on the volcano. We surveyed the volcano's caldera complex, flank terraces, pit structures, sinuous rilles, arcuate grabens, and small vents. We report the spatial and temporal distributions of these features, appraise their proposed formation mechanisms in light of our mapping results, and propose a detailed geological history for Ascraeus Mons. An initial shield-building phase was followed by the formation of a summit caldera complex and small parasitic cones, while compression due to flexure of the supporting basement led to extensive terracing of the shield flanks. An eruptive hiatus followed, ending with the construction of expansive rift aprons to the northeast and southwest. Against later, extensive flank resurfacing in the late Amazonian, continued flexure formed arcuate grabens concentric to the edifice. Localized eruption and surface flow of a fluid agent (lava and/or water) from within the volcano then produced a population of rilles on the lower flanks. Finally, in a change of flank tectonic regime from compression to extension, pit crater chains and troughs developed on the main shield and rift aprons, eventually coalescing to form large embayments at the northeast and southwest base of the volcano.}, number={E1}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Byrne, Paul K. and van Wyk de Vries, Benjamin and Murray, John B. and Troll, Valentin R.}, year={2012}, month={Jan} }
 @article{weider_nittler_starr_mccoy_stockstill-cahill_byrne_denevi_head_solomon_2012, title={Chemical heterogeneity on Mercury's surface revealed by the MESSENGER X-Ray Spectrometer}, volume={117}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2012JE004153}, DOI={10.1029/2012JE004153}, abstractNote={[1] We present the analysis of 205 spatially resolved measurements of the surface composition of Mercury from MESSENGER’s X-Ray Spectrometer. The surface footprints of these measurements are categorized according to geological terrain. Northern smooth plains deposits and the plains interior to the Caloris basin differ compositionally from older terrain on Mercury. The older terrain generally has higher Mg/Si, S/Si, and Ca/Si ratios, and a lower Al/Si ratio than the smooth plains. Mercury’s surface mineralogy is likely dominated by high-Mg mafic minerals (e.g., enstatite), plagioclase feldspar, and lesser amounts of Ca, Mg, and/or Fe sulfides (e.g., oldhamite). The compositional difference between the volcanic smooth plains and the older terrain reflects different abundances of these minerals and points to the crystallization of the smooth plains from a more chemically evolved magma source. High-degree partial melts of enstatite chondrite material provide a generally good compositional and mineralogical match for much of the surface of Mercury. An exception is Fe, for which the low surface abundance on Mercury is still higher than that of melts from enstatite chondrites and may indicate an exogenous contribution from meteoroid impacts.}, number={E12}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Weider, Shoshana Z. and Nittler, Larry R. and Starr, Richard D. and McCoy, Timothy J. and Stockstill-Cahill, Karen R. and Byrne, Paul K. and Denevi, Brett W. and Head, James W. and Solomon, Sean C.}, year={2012}, month={Oct}, pages={n/a-n/a} }
 @article{klimczak_watters_ernst_freed_byrne_solomon_blair_head_2012, title={Deformation associated with ghost craters and basins in volcanic smooth plains on Mercury: Strain analysis and implications for plains evolution}, volume={117}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2012JE004100}, DOI={10.1029/2012JE004100}, abstractNote={[1] Since its insertion into orbit about Mercury in March 2011, the MESSENGER spacecraft has imaged most previously unseen regions of the planet in unprecedented detail, revealing extensive regions of contiguous smooth plains at high northern latitudes and surrounding the Caloris basin. These smooth plains, thought to be emplaced by flood volcanism, are populated with several hundred ghost craters and basins, nearly to completely buried impact features having rims for which the surface expressions are now primarily rings of deformational landforms. Associated with some ghost craters are interior groups of graben displaying mostly polygonal patterns. The origin of these graben is not yet fully understood, but comparison with numerical models suggests that the majority of such features are the result of stresses from local thermal contraction. In this paper, we highlight a previously unreported category of ghost craters, quantify extensional strains across graben-bearing ghost craters, and make use of graben geometries to gain insights into the subsurface geology of smooth plains areas. In particular, the style and mechanisms of graben development imply that flooding of impact craters and basins led to substantial pooling of lavas, to thicknesses of ∼1.5 km. In addition, surface strains derived from groups of graben are generally in agreement with theoretically and numerically derived strains for thermal contraction.}, number={E12}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Klimczak, Christian and Watters, Thomas R. and Ernst, Carolyn M. and Freed, Andrew M. and Byrne, Paul K. and Solomon, Sean C. and Blair, David M. and Head, James W.}, year={2012}, month={Sep}, pages={n/a-n/a} }
 @article{starr_schriver_nittler_weider_byrne_ho_rhodes_schlemm_solomon_trávníček_2012, title={MESSENGER detection of electron-induced X-ray fluorescence from Mercury's surface}, volume={117}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2012JE004118}, DOI={10.1029/2012JE004118}, abstractNote={[1] The X-Ray Spectrometer (XRS) on the MESSENGER spacecraft measures elemental abundances on the surface of Mercury by detecting fluorescent X-ray emissions induced on the planet's surface by the incident solar X-ray flux. The XRS began orbital observations on 23 March 2011 and has observed X-ray fluorescence (XRF) from the surface of the planet whenever a sunlit portion of Mercury has been within the XRS field of view. Solar flares are generally required to provide sufficient signal to detect elements that fluoresce at energies above ∼2 keV, but XRF up to the calcium line (3.69 keV) has been detected from Mercury's surface at times when the XRS field of view included only unlit portions of the planet. Many such events have been detected and are identified as electron-induced X-ray emission produced by the interaction of ∼1–10 keV electrons with Mercury's surface. Electrons in this energy range were detected by the XRS during the three Mercury flybys and have also been observed regularly in orbit about Mercury. Knowledge of the energy spectrum of the electrons precipitating at the planet's surface makes it possible to infer surface composition from the measured fluorescent spectra, providing additional measurement opportunities for the XRS. Abundance results for Mg, Al, and Si are in good agreement with those derived from solar-induced XRF data, providing independent validation of the analysis methodologies. Derived S and Ca abundances are somewhat higher than derived from the solar-induced fluorescence data, possibly reflecting incomplete knowledge of the energy spectra of electrons impacting the planet.}, number={E12}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Starr, Richard D. and Schriver, David and Nittler, Larry R. and Weider, Shoshana Z. and Byrne, Paul K. and Ho, George C. and Rhodes, Edgar A. and Schlemm, Charles E., II and Solomon, Sean C. and Trávníček, Pavel M.}, year={2012}, month={Aug}, pages={n/a-n/a} }
 @article{freed_blair_watters_klimczak_byrne_solomon_zuber_melosh_2012, title={On the origin of graben and ridges within and near volcanically buried craters and basins in Mercury's northern plains}, volume={117}, ISSN={0148-0227}, url={http://dx.doi.org/10.1029/2012JE004119}, DOI={10.1029/2012JE004119}, abstractNote={[1] Images of Mercury’s northern volcanic plains taken by the MESSENGER spacecraft reveal a large number of buried impact craters and basins discernible by wrinkle-ridge rings that overlie their rims. Many of these “ghost” craters and basins contain interior graben of diverse widths and orientations. Here we use finite element models to test a variety of mechanisms for the formation of these graben and ridges. Results show that graben are best explained by cooling of large thicknesses of flood lavas within the craters and basins; conservation of surface area during cooling induces the required extensional stress state. In contrast, the development of wrinkle-ridge rings is best explained as the result of cooling and contraction of Mercury’s interior, during which a reduction in Mercury’s surface area led to a compressional state of stress. The critical factor in determining where large graben form is the thickness of the youngest cooling unit, the topmost sequence of lavas that cooled coevally. A thicker cooling unit leads to a deeper initiation of normal faulting (wider graben floors). Consistent with observations, the widest graben are predicted to occur where pooled lavas were thickest, and no graben are predicted within generally thinner plains outside of major craters. Observed concentrically oriented graben can be explained by variations in the thickness of the youngest cooling unit. In contrast, none of the basin uplift mechanisms considered, including isostatic response to crater topography, inward flow of the lower crust, or exterior loading by volcanic plains, can account for concentrically oriented graben.}, number={E12}, journal={Journal of Geophysical Research: Planets}, publisher={American Geophysical Union (AGU)}, author={Freed, Andrew M. and Blair, David M. and Watters, Thomas R. and Klimczak, Christian and Byrne, Paul K. and Solomon, Sean C. and Zuber, Maria T. and Melosh, H. J.}, year={2012}, month={Oct}, pages={n/a-n/a} }
 @article{mathieu_byrne_guillaume_van wyk de vries_moine_2011, title={The field and remote sensing analysis of the Kerguelen Archipelago structure, Indian Ocean}, volume={199}, ISSN={0377-0273}, url={http://dx.doi.org/10.1016/j.jvolgeores.2010.11.013}, DOI={10.1016/j.jvolgeores.2010.11.013}, abstractNote={The Kerguelen Archipelago is part of an oceanic plateau with a complex history. Little work has been done on the tectonics of the onshore areas, even though the extensive outcrop renders the islands especially good for structural work. We present the results of three field campaigns and remote sensing analysis carried out in the main Kerguelen Island, around Val Travers valley and Mt Ross volcano (Central Plateau) and in the Rallier du Baty peninsula (SW part of the archipelago). We have mapped faults, fracture sets, and the location and geometry of intrusive bodies. We found that the plateau basalt lavas that make up most of the area are densely fractured, crossed by many veins, dykes and some small faults. This work provides a general framework for the structure of Kerguelen Archipelago that is dominated by 110°-striking faults and veins, dyke swarms and an alignment of recent central volcanoes, which have formed in N-S to NNW-SSE directed extensional stress field. The other structures are fractures, veins and dykes which strike 130–150°, 000° and 030–050°. They are likely related to transform faults of the Indian oceanic crust and to faults of the north Kerguelen Plateau (offshore basement of the archipelago). These buried structures were likely re-activated by a low magnitude stress field.}, number={3-4}, journal={Journal of Volcanology and Geothermal Research}, publisher={Elsevier BV}, author={Mathieu, Lucie and Byrne, Paul and Guillaume, Damien and van Wyk de Vries, Benjamin and Moine, Bertrand}, year={2011}, month={Jan}, pages={206–215} }
 @article{murray_van wyk de vries_marquez_williams_byrne_muller_kim_2010, title={Late-stage water eruptions from Ascraeus Mons volcano, Mars: Implications for its structure and history}, volume={294}, ISSN={0012-821X}, url={http://dx.doi.org/10.1016/j.epsl.2009.06.020}, DOI={10.1016/j.epsl.2009.06.020}, abstractNote={Ascraeus Mons was one of the first of the Martian volcanoes to be imaged by the High Resolution Stereo Camera (HRSC) experiment onboard the ESA Mars Express spacecraft. These images show much of the volcano at a higher resolution than previously, and details of its lava flows, sinuous rilles, flank vents and tectonic features indicate an unexpected origin for some of these features. We establish the time-stratigraphic sequence for these features, and use a numerical model on HRSC stereo DTMs of the sinuous rilles, and conclude that they were formed by water erosion. Terrestrial analogues for such features are found at Réunion Island and other volcanoes. We then examine the overall structure of the volcano, which is dissimilar to that of large terrestrial volcanoes in important respects, and perform laboratory analogue experiments of its deformation, concluding that the tectonic features were formed by sinking of the volcano into a substratum that was much weaker than the volcanic edifice. An ice-rich substratum melted by a combination of pressure melting and magmatic heating seems the most likely mechanism. Analogous water-escape structures in a similar volcanic situation have been identified at Mt Haddington in the Antarctic. The possible role of a hydrological cycle and a hydrothermal system within the volcano are discussed. Based on field evidence, we propose that much of the broad aprons of lobate flows issuing from the NE and SSW foot of Ascraeus Mons are composed of mudflows rather than lava flows. These different approaches are linked into a coherent history of this volcano. The similarity of Ascraeus Mons to Pavonis Mons and Arsia Mons (though Ascraeus is younger) suggests that some of our conclusions may apply to these volcanoes too.}, number={3-4}, journal={Earth and Planetary Science Letters}, publisher={Elsevier BV}, author={Murray, John B. and van Wyk de Vries, B. and Marquez, Alvaro and Williams, David A. and Byrne, Paul and Muller, Jan-Peter and Kim, Jung-Rack}, year={2010}, month={Jun}, pages={479–491} }
 @article{byrne_van wyk de vries_murray_troll_2009, title={The geometry of volcano flank terraces on Mars}, volume={281}, ISSN={0012-821X}, url={http://dx.doi.org/10.1016/j.epsl.2009.01.043}, DOI={10.1016/j.epsl.2009.01.043}, abstractNote={Flank terraces are subtle, expansive structures on the slopes of many large Martian shield volcanoes. Several terrace formation hypotheses — including self-loading, lithospheric flexure, magma chamber tumescence, volcano spreading, and shallow gravitational slumping — have been suggested. Terraces are not readily visible on photogeological data; consequently, terrace geometry has not yet been comprehensively described. Terrace provenance, therefore, is poorly understood. We used three-dimensional Mars Orbiter Laser Altimeter (MOLA) data to characterise the geometry of these elusive structures, with a view to understanding better the role that flank terraces play in the tectonic evolution of volcanoes on Mars. Terraces have a broad, convex-upward profile in section, and a systematic “fish scale” imbricate stacking pattern in plan. They are visible at all elevations, on at least nine disparate Martian volcanoes. Terrace-like features also occur on three shield volcanoes on Earth, an observation not recorded before. Analysis of a suite of morphometric parameters for flank terraces showed that they are scale-invariant, with similar proportions to thrust faults on Earth. We compared predicted formation geometries to our terrace observations, and found that only lithospheric flexure can fully account for the morphology, distribution, and timing of terraces. As a volcano flexes into the lithosphere beneath it, its upper surface will experience a net reduction in area, resulting in the formation of outward verging thrusts. We conclude, therefore, that flank terraces are fundamental volcanotectonic structures, that they are the surface expressions of thrust faults, probably formed by lithospheric flexure, and that they are not restricted to Mars.}, number={1-2}, journal={Earth and Planetary Science Letters}, publisher={Elsevier BV}, author={Byrne, Paul K. and van Wyk de Vries, Benjamin and Murray, John B. and Troll, Valentin R.}, year={2009}, month={Apr}, pages={1–13} }