@article{steltenpohl_carter_andresen_zeltner_2009, title={40Ar/39Ar Thermochronology of Late- and Postorogenic Extension in the Caledonides of North-Central Norway}, volume={117}, ISSN={["1537-5269"]}, DOI={10.1086/599217}, abstractNote={We report 40Ar/39Ar mineral cooling data that elucidate the timing and style of Devonian late‐orogenic extensional collapse and Permian‐Triassic postorogenic continental rifting in the north‐central Norwegian Caledonides. 40Ar/39Ar mineral cooling ages from ductile extensional shear zones that have either excised or reactivated Caledonian thrust faults along the western flanks of two major basement domes indicate that late‐orogenic extensional deformation in this region occurred during the Early (ca. 409–388 Ma) and Late Devonian (ca. 371–355 Ma). These extensional pulses are consistent with events recently identified by workers investigating areas to the south of our study area. The timing and style of the Early Devonian event supports the northern continuation of the Devonian orogen‐parallel, scoop‐shaped extensional deformation documented in the central Norwegian Caledonides. Late Devonian extension, on the other hand, was orogen‐orthogonal. This Late Devonian event is similar in timing and kinematics to the extension documented in the Lofoten Archipelago due west of our study area. 40Ar/39Ar data on K‐feldspar samples from brittle extensional faults of the Vestfjord‐Vanna fault complex, which opened the major NNE‐SSW‐trending Vestfjord basin, document two pulses of E‐W‐directed postorogenic continental rifting. The first pulse of extension occurred during the Early Permian, at ca. 272 Ma, and the other during the Middle Triassic, at ca. 236 Ma. The Early Permian faults are upper‐crustal features found in the hanging wall of the Lofoten metamorphic core complex, the result of rifting the Lofoten block from the Norwegian mainland during the initial opening of the Vestfjord basin. Middle Triassic faulting occurred because of continued movement along the Vestfjord‐Vanna fault complex during further development of the Vestfjord basin. The timing and kinematics of development of the Vestfjord basin have similarities with those of major basins submerged along and exposed on the continental margins of Norway and Greenland, respectively. Permian‐Triassic extension, long recognized throughout eastern Greenland, is evidently more pronounced along the Norwegian continental margin than was previously thought. We interpret this event as marking the transition from Devonian‐Carboniferous extensional collapse to continental rifting sensu stricto, preceding the Eocene opening of the nascent Norwegian‐Greenlandian Sea.}, number={4}, journal={JOURNAL OF GEOLOGY}, author={Steltenpohl, Mark G. and Carter, Brad T. and Andresen, Arild and Zeltner, Daniel L.}, year={2009}, month={Jul}, pages={399–414} }
 @article{carter_hibbard_tubrett_sylvester_2006, title={Detrital zircon geochronology of the Smith River Allochthon and Lynchburg Group, southern Appalachians: Implications for Neoproterozoic-Early Cambrian paleogeography}, volume={147}, ISSN={["1872-7433"]}, DOI={10.1016/j.precamres.2006.01.024}, abstractNote={A detrital zircon geochronological study was undertaken to provide insight into the Neoproterozoic-Early Cambrian paleo-continental affinity of the Smith River Allochthon (SRA). The SRA has been depicted by some authors to represent a distal facies equivalent of the Lynchburg Group, a rift-related sequence that originated along the Laurentian margin during the Neoproterozoic-Early Cambrian opening of the Iapetus Ocean. Other workers, however, have interpreted the SRA as being exotic with respect to Laurentia and possibly of Gondwanan origin. The most predominant detrital age population in both terranes ranges from 0.9 to 1.25 Ga. Both terranes also contain minor populations ranging from 0.75 to 0.9 Ga and 1.3 to 1.4 Ga. The SRA also contains a minor population ranging from 1.4 to 1.5 Ga. The youngest detrital zircon ages in both terranes are <900 Ma. Uranium (U) concentrations in the zircons were also determined. The U concentration versus age plot of the SRA samples is similar to that of the Lynchburg Group. The majority of the grains in both terranes contain less than 500 ppm U, with the Lynchburg Group zircons containing a higher mean U concentration than the SRA (307 ppm versus 226 ppm). The striking similarities of the detrital zircon age and chemical data for the SRA and Lynchburg Group samples suggest that the SRA and Lynchburg Group share a common provenance along the Laurentian margin. These data conflict with electron microprobe (EPMA) monazite geochronological data that document an Early Cambrian tectonothermal event in the SRA. The eastern Laurentian margin was in the rift-to-drift transition by the Early Cambrian, so a tectonothermal event along the Laurentian margin at this time is difficult to envision. Based on the striking similarities of the detrital zircon data, we suggest that the SRA is most likely a distal facies equivalent of the Lynchburg Group, and thus of Laurentian origin, even though it records an Early Cambrian tectonothermal event. This interpretation is consistent with some interpretations of peri-Laurentian affinity for other terranes in the Piedmont zone of the southern Appalachians.}, number={3-4}, journal={PRECAMBRIAN RESEARCH}, author={Carter, Brad T. and Hibbard, James P. and Tubrett, Mike and Sylvester, Paul}, year={2006}, month={Jul}, pages={279–304} }