@article{sjoblom_dorais_christiansen_fodor_2023, title={Mafic to ultramafic xenoliths from Mauna Kea, Hawaii: clues to magma evolution from trace element compositions of clinopyroxene}, volume={178}, ISSN={["1432-0967"]}, DOI={10.1007/s00410-023-02001-3}, number={3}, journal={CONTRIBUTIONS TO MINERALOGY AND PETROLOGY}, author={Sjoblom, Megan Pickard and Dorais, Michael J. J. and Christiansen, Eric H. H. and Fodor, Ronald V. V.}, year={2023}, month={Mar} }
 @article{dombroski_fodor_2019, title={The Miocene Goldfield-Superstition volcanic province, Central Arizona, USA: Geochemically distinct rhyolite sources, 20.5 to 19 Ma}, volume={330}, ISSN={["1872-6143"]}, DOI={10.1016/j.lithos.2019.02.008}, abstractNote={The Miocene Goldfield-Superstition volcanic province (G-SVP) in central Arizona is composed of silicic pyroclastic and lava flows, and, to a small extent, silicic domes, and mafic and intermediate lavas. Volcanism began ~20.5 Ma with small-scale silicic domes, followed by ≤1.5 m.y. of basaltic, andesitic, and dacitic lavas, after which large-scale pyroclastic flows and lavas created the bulk of this large province from ~19 to 18.5 Ma (~8000 km2). Rhyolite compositions dominate the G-SVP and our observations are that the earliest expressions, small-scale domes, had crustal sources geochemically different from those for the main mass of lavas and ash-flow tuffs. In particular, three early domes, while rhyolites, have notably low REE and HFSE abundances for high-SiO2 rocks (e.g., La 8–34 ppm; Zr 32–92; Nb 8–17, Th 6–7), generally lower than the abundances in overlying alkalic basalt lavas. They form two groups: one is higher in SiO2 (~77–79 wt%) than the other (~70–73 wt% SiO2). Both groups are crystal poor, from ~3 to 8 vol%. Modal mineralogy is mainly oligoclase, alkali feldspar, and quartz in the high-SiO2 group, and andesine and biotite in the low-SiO2 group. The high-SiO2 rhyolite domes have REE patterns that are nearly flat (La/Yb(n) 9–16), whereas the low-SiO2 domes have steeper REE patterns (La/Yb(n) 46–56). In comparison, the lavas and tuffs that erupted beginning ~1.5 m.y. later have REE patterns and higher REE and HFSE abundances (e.g., La largely 45–80 ppm; Nb 17–30; Th 9–20) characteristic of rhyolites in other western North American Oligocene-Miocene silicic large provinces. Their modal mineralogy (~2–13 vol% tuffs; ~5 to 26 vol% lavas) is andesine, oligoclase, alkali feldspar, quartz, biotite, edenitic amphibole, +/− pyroxene, titanite, zircon, and REE-rich perrierite. Our interpretation is that the earliest magmatism in the G-SVP – namely the domes – represents small percent (e.g., ≤10%) partial melts of lower crust amphibolite that had low trace element abundances, both with and without garnet (to influence the REE pattern slopes). Melting is attributed to heat from early stages of basaltic magmatism. The younger rhyolite lavas and pyroclastic flows are products of middle to upper granitoid crust anatexis (e.g., 40–60%) resulting from continual basalt magma injections up to 2 m.y. following dome emplacement (i.e., from ~20.5 to 19–18.5 Ma). The G-SVP therefore chronologically and geochemically tracks the change in sources for rhyolites over ~2 m.y. of volcanism to create a central Arizona large igneous province.}, journal={LITHOS}, author={Dombroski, Brian A. and Fodor, R.}, year={2019}, month={Apr}, pages={139–159} }
 @article{craig_fodor_2018, title={Sugarloaf Mountain, central Arizona, USA: A small-scale example of Miocene basalt-rhyolite magma mixing to yield andesitic magmas}, volume={78}, ISSN={["1611-5864"]}, DOI={10.1016/j.chemer.2017.11.001}, abstractNote={Sugarloaf Mountain is a 200-m high volcanic landform in central Arizona, USA, within the transition from the southern Basin and Range to the Colorado Plateau. It is composed of Miocene alkalic basalt (47.2–49.1 wt.% SiO2; 6.7–7.7 wt.% MgO) and overlying andesite and dacite lavas (61.4–63.9 wt.% SiO2; 3.5–4.7 wt.% MgO). Sugarloaf Mountain therefore offers an opportunity to evaluate the origin of andesite magmas with respect to coexisting basalt. Important for evaluating Sugarloaf basalt and andesite (plus dacite) is that the andesites contain basaltic minerals olivine (cores Fo76-86) and clinopyroxene (∼Fs9-18Wo35-44) coexisting with Na-plagioclase (An48-28Or1.4–7), quartz, amphibole, and minor orthopyroxene, biotite, and sanidine. Noteworthy is that andesite mineral textures include reaction and spongy zones and embayments in and on Na-plagioclase and quartz phenocrysts, where some reacted Na-plagioclases have higher-An mantles, plus some similarly reacted and embayed olivine, clinopyroxene, and amphibole phenocrysts. Fractional crystallization of Sugarloaf basaltic magmas cannot alone yield the andesites because their ∼61 to 64 wt.% SiO2 is attended by incompatible REE and HFSE abundances lower than in the basalts (e.g., Ce 77–105 in andesites vs 114–166 ppm in basalts; Zr 149–173 vs 183–237; Nb 21–25 vs 34–42). On the other hand, andesite mineral assemblages, textures, and compositions are consistent with basaltic magmas having mixed with rhyolitic magmas, provided the rhyolite(s) had relatively low REE and HFSE abundances. Linear binary mixing calculations yield good first approximation results for producing andesitic compositions from Sugarloaf basalt compositions and a central Arizona low-REE, low-HFSE rhyolite. For example, mixing proportions 52:48 of Sugarloaf basalt and low incompatible-element rhyolite yields a hybrid composition that matches Sugarloaf andesite well − although we do not claim to have exact endmembers, but rather, viable proxies. Additionally, the observed mineral textures are all consistent with hot basalt magma mixing into rhyolite magma. Compositional differences among the phenocrysts of Na-plagioclase, clinopyroxene, and amphibole in the andesites suggest several mixing events, and amphibole thermobarometry calculates depths corresponding to 8–16 km and 850° to 980 °C. The amphibole P-T observed for a rather tight compositional range of andesite compositions is consistent with the gathering of several different basalt-rhyolite hybrids into a homogenizing ‘collection' zone prior to eruptions. We interpret Sugarloaf Mountain to represent basalt-rhyolite mixings on a relatively small scale as part of the large scale Miocene (∼20 to 15 Ma) magmatism of central Arizona. A particular qualification for this example of hybridization, however, is that the rhyolite endmember have relatively low REE and HFSE abundances.}, number={1}, journal={CHEMIE DER ERDE-GEOCHEMISTRY}, author={Craig, Ellen J. and Fodor, R.}, year={2018}, pages={116–139} }
 @article{fodor_johnson_2016, title={Origin of Miocene andesite and dacite in the Goldfield-Superstition volcanic province, central Arizona: Hybrids of mafic and silicic magma mixing}, volume={185}, ISSN={["1872-9533"]}, DOI={10.1016/j.gca.2016.04.001}, abstractNote={The Miocene Goldfield–Superstition volcanic province (G-SVP), ∼8000 km2 in central Arizona, is composed largely of silicic pyroclastic rocks and lavas, and smaller volumes of alkalic basalt and intermediate-composition lavas. Volcanism began ∼20.5 Ma as sparse rhyolitic and mainly basaltic lavas followed by intermediate lavas, lasting until ∼19 Ma. At that time, ∼1 m.y. of silicic eruptions began, creating most of the G-SVP. Petrologic studies are available for basalts and some for silicic rocks, but petrologic/geochemical information is sparse for intermediate-composition lavas. These latter, andesites and dacites, are the focus of this study, in which we present the processes and sources responsible for their origins. Goldfield–Superstition andesites and dacites have SiO2 ∼56–70 wt.% and Na2O + K2O that qualifies some as trachy-andesite and -dacite. A prominent petrographic feature is plagioclase-phyric texture (∼11–30 vol% plagioclase), where oligoclase–andesine phenocrysts have cores surrounded by corroded, or reacted, zones, mantled by higher An% plagioclase. Where corroded zones are absent, margins are etched, curved, or embayed. Groundmass plagioclase is labradorite, also more calcic than the phenocrysts. Other minerals are quartz (subrounded; embayed), clinopyroxene, amphibole, biotite, and rare titanite and zircon. A salient compositional characteristic that provides insight to andesite–dacite origins with respect to other G-SVP rocks is revealed when using SiO2 as an index. Namely, abundances of many incompatible elements, mainly HFSE and REE, decrease over the low to high SiO2 range (i.e., abundances are lower in dacites than in co-eruptive andesites and underlying alkalic basalts). As examples: G-SVP basalts have ∼50–70 ppm La, and andesites–dacites have ∼59–22 ppm La; for Zr, basalts have ∼225–170 ppm, but most andesites–dacites have ∼180–50; for Y, basalts >20 ppm, andesites–dacites ∼18–9 ppm. To understand these trends of lower HFSE and REE with increasing SiO2, we modeled fractional crystallization of G-SVP alkalic basalt (∼50 wt.% SiO2; ∼9 wt.% MgO), dehydration melting (10–25%) of granodiorite and high-K amphibolite, and basalt–rhyolite magma mixing. Fractionation and melting each require specific modal percentages of titanite, zircon, and allanite (e.g., ⩽1%), the high ends of ranges for accessory-mineral/liquid partitioning coefficients, continual crystallization of accessory minerals from basalt to dacite (for fractionation), and specific source-melting percentages and low titanite, zircon, and allanite melting proportions (∼0.02; dehydration melting). These requirements are too stringent to be realistic. Moreover, accessory minerals are rare in these lavas, and neither fractionation nor melting accounts for the plagioclase textures observed. On the other hand, low-HFSE, -REE rhyolites (e.g., La 9–31 ppm; Zr 31–93; Nb 9–17; Y 4–10) containing Na-plagioclase are in the G-SVP and were temporally and spatially available to have mixed with G-SVP basalts. Mixing proportions of 20:80 to 90:10 for different rhyolite:basalt combinations yield hybrid compositions that overlap the G-SVP andesite–dacite compositional fields. Also, basalt invading rhyolite reservoirs containing mush zones can account for Na-plagioclase concentrations of ∼11–30 vol% formed after mush disruption and dispersal, plagioclase corroded-cores and higher-An% mantles and groundmass, and subrounded-embayed quartz. The straightforward explanation for G-SVP intermediate lavas, then, is repeated hybridization of basaltic and low-HFSE, -REE rhyolitic magmas during the early stages of G-SVP magmatism.}, journal={GEOCHIMICA ET COSMOCHIMICA ACTA}, author={Fodor, R. V. and Johnson, Kelly G.}, year={2016}, month={Jul}, pages={394–417} }
 @article{fodor_bauer_2014, title={Diabasic intrusion and lavas, segregation veins, and magma differentiation at Kahoolawe volcano, Hawaii}, volume={108}, DOI={10.1007/s00710-013-0299-x}, number={2}, journal={Mineralogy and Petrology}, author={Fodor, R. V. and Bauer, G. R.}, year={2014}, pages={269–286} }
 @article{huang_blichert-toft_fodor_bauer_bizimis_2013, title={Sr, Nd, Hf and Pb isotope systematics of postshield-stage lavas at Kahoolawe, Hawaii}, volume={360}, ISSN={["1872-6836"]}, DOI={10.1016/j.chemgeo.2013.10.021}, abstractNote={We report high-precision Sr, Nd, Hf and Pb isotope compositions for twenty-one postshield-stage and two post-caldera lavas from Kahoolawe, a Loa-trend Hawaiian volcano. Kahoolawe postshield- and shield-stage lavas have overlapping though highly heterogeneous Sr, Nd, Hf and Pb isotope compositions, implying that the shield- and postshield-stage volcanism at Kahoolawe sampled the same isotopically heterogeneous mantle source. This differs from that of most other Hawaiian volcanoes, such as Haleakala, Mauna Kea, and Hualalai, whose shield-to-postshield transitions are characterized by shifts to lower 87Sr/86Sr and higher 143Nd/144Nd. There are correlations between CaO, Sc and V contents and radiogenic isotope compositions within Kahoolawe postshield-stage lavas. For example, Sc abundance is negatively correlated with 87Sr/86Sr, and positively correlated with εNd and εHf; V abundance is positively correlated with εNd, εHf, and 206Pb/204Pb. Element-isotope correlations are also observed in Mauna Kea postshield-stage lavas: Sc and V abundances are negatively correlated with εHf and 206Pb/204Pb, and positively correlated with εNd. These trends may be due to magma–magma mixing. That is, in addition to clinopyroxene fractionation to account for the low CaO, Sc and V contents in some postshield-stage lavas, partial melts of eclogite/garnet pyroxenite, characterized by low CaO, Sc and V contents, may also be part of the petrogenesis of Kahoolawe postshield-stage lavas. It is well established that lavas erupted at the geographically defined Loa- and Kea-trend volcanoes have different isotopic and geochemical compositions. Specifically, compared to the Kea-trend lavas, Loa-trend lavas have higher 208Pb/204Pb at a given 206Pb/204Pb. However, cases exist of both shield- and postshield-stage volcanism where Kea-type isotopic signatures are present in Loa-trend volcanoes and the reverse. We propose that Loa- and Kea-type source components are present beneath both Loa- and Kea-trend volcanoes in such a way that the average source compositions of Loa-trend volcanoes have a Loa-type isotopic signature, and that of the Kea-trend volcanoes have a Kea-type isotopic signature. When the size of the magma capture zone is much larger than that of the source components, the erupted lavas have the average compositions of the source. If the size of the magma capture zone is comparable to that of the source components, the erupted lavas could have either Loa- or Kea-type isotopic signatures.}, journal={CHEMICAL GEOLOGY}, author={Huang, Shichun and Blichert-Toft, Janne and Fodor, R. V. and Bauer, Glenn R. and Bizimis, Michael}, year={2013}, month={Dec}, pages={159–172} }
 @article{fodor_bauer_2012, title={Did Kahoolawe Volcano, Hawaii, Evolve to Alkalic Composition Magmatism?}, volume={120}, ISSN={["0022-1376"]}, DOI={10.1086/663874}, abstractNote={AbstractUncertainty remains about whether Kahoolawe, the smallest of the main Hawaiian Islands, evolved to alkalic magmatism. To determine the compositional extent to which Kahoolawe volcano evolved, we examined eight new samples as candidates for hawaiite, an unequivocally alkalic rock type. Petrography (e.g., commonly aphyric) and major- and trace-element and mineral compositions (e.g., ∼49.5 wt% SiO2 at ∼6 wt% Na2O+K2O; An∼50–60) document that four are hawaiites and two are mugearites (the other two are basalts). These six samples have compositions that overlap or are similar to those of known Hawaiian hawaiites and mugearites. Some trace-element differences (e.g., the highest Ni and lowest Sr) probably represent particular source characteristics for Kahoolawe hawaiites. Mass balancing and MELTS modeling suggest that these Kahoolawe lavas represent ∼58%–65% residual liquids from alkalic basalt clinopyroxene-dominated crystallization at pressures approaching that of the crust-mantle boundary. These mode...}, number={2}, journal={JOURNAL OF GEOLOGY}, author={Fodor, R. V. and Bauer, G. R.}, year={2012}, month={Mar}, pages={191–202} }
 @misc{fodor_bauer_2010, title={Kahoolawe Island, Hawaii: The role of an 'inaccessible' shield volcano in the petrology of the Hawaiian islands and plume}, volume={70}, ISSN={["0009-2819"]}, DOI={10.1016/j.chemer.2010.01.001}, abstractNote={Kahoolawe volcano (∼10×17 km) forms one of the eight major Hawaiian islands. Access for geologic sampling has long been restricted due to military and preservation policies. However, limited visits to Kahoolawe in the 1980s yielded >200 samples, many of which have since been used to study the volcano within the framework of Hawaiian shield and mantle source geochemistry, petrology, mineralogy, and igneous processes. Kahoolawe is a tholeiitic shield with tholeiitic caldera-filling lavas, and at least seven postshield vents that erupted tholeiitic and (sparse) alkalic lavas. On smaller scales are a gabbro intrusion and ultramafic and gabbroic xenoliths in some postshield lavas. There is no evidence for rejuvenated volcanism. In its structural setting, Kahoolawe lies along the “Loa” trend of Hawaiian shields. Major element compositions of shield and caldera-filling lavas are similar and cluster at ∼6–7 wt% MgO, range from ∼5.5 to 16 wt% MgO, and include ∼9 wt% MgO examples that can be modeled as parental to the evolved lavas. For example, least squares mass balancing demonstrates that from ∼15% to 30% crystallization of olivine (±orthopyroxene), clinopyroxene, and plagioclase accounts for the ∼5.5–6 wt% MgO range of tholeiitic lavas. Greater differentiation occurred in the gabbro (diabasic) intrusive body as a segregation vein with ∼2.9 wt% MgO, and extreme differentiation produced local, small-volume rhyolitic melts that segregated into lava vesicles. Postshield lavas are mainly tholeiitic, have ∼5–7 wt% MgO, and overlap shield compositions. Some are alkalic, as low as ∼3.9 wt% MgO (hawaiite), and can be modeled as liquids after a ∼9 wt% MgO alkalic magma crystallized ∼30% olivine, clinopyroxene, plagioclase, and magnetite. Important aspects of Sr, Nd, Hf, and Pb isotopic ratios in Kahoolawe shield and caldera-filling lavas are slightly higher 87Sr/86Sr than in Koolau shield lavas (Oahu island; Makapuu-stage; e.g., Koolau mantle ‘endmember’) when compared at a given 143Nd/144Nd (e.g., ∼0.7042 at 0.5128), 206Pb/204Pb largely at the low end of the range for Hawaiian shields (e.g., ∼18), and εHf generally comparable to the values of other Hawaiian shields and ocean islands (e.g., εHf 8 at εNd 4). The isotopic ratios overall suggest small-scale source heterogeneity, considering the island size, and that Kahoolawe shield and caldera lavas were derived from a Hawaiian plume source containing recycled oceanic crust of gabbro and sediments. Based on certain geochemical indicators, however, such as Ce/Sr and La/Nb vs. 87Sr/86Sr, the source contained slightly less gabbro component than other shield sources (e.g., Koolau). Isotopic data for Kahoolawe postshield lavas are scarce, but those available generally overlap the shield data. However, ratios among certain alteration-resistant incompatible trace elements (e.g., Zr/Nb) discriminate some postshield alkalic from shield lavas. But because the different ratios for those postshield lavas can be explained by smaller partial-melting percentages of the shield source and by differentiation, neither isotopes nor trace elements identify postshield magmas as originating in a source unlike that for the shield lavas.}, number={2}, journal={CHEMIE DER ERDE-GEOCHEMISTRY}, author={Fodor, R. V. and Bauer, G. R.}, year={2010}, pages={101–123} }
 @article{fodor_2009, title={Diorite Segregations in Gabbro: Geochemical Characteristics and Conditions for Origin Assessed at Diorite-Gabbro Contacts}, volume={117}, ISSN={["0022-1376"]}, DOI={10.1086/596506}, abstractNote={Silicic segregation veins in the Basement Sill, Dry Valleys, Antarctica, represent fracture-filling liquids differentiated from mid-Jurassic Ferrar tholeiitic basalt magmas. Geochemical and mineralogical characterizations for several of these veins and for their host gabbros within centimeters of sharp contacts with the veins provide information about silicic liquid produced from basalt in closed systems. The Basement Sill silicic veins are coarse- to pegmatite-textured diorites (∼60 wt% SiO2; 1.6%–2.6% MgO) composed of Fe-rich clinopyroxene (cpx; Fs20-60) and orthopyroxene (and pigeonite), ∼An50-60 plagioclase, and ∼20–30 vol% mesostases of micrographic quartz + alkali feldspar (∼Or80-90). The host gabbros (52–54 wt% SiO2; 5.5%–9.2% MgO) within ∼2 cm of veins contain pyroxene and feldspar with compositions that range from overlapping those in the diorite veins to those closer to characteristic of gabbro (e.g., cpx ∼Fs20; ∼An60-80) but unlike the more primitive mineral compositions representing the Basement Sill as a whole (e.g., ∼Fs15). The gabbros also contain interstitial micrographic quartz + alkali feldspar. Evolved minerals and quartz + alkali feldspar in gabbro at vein contacts are signatures consistent with evolved interstitial liquids having migrated through the sill’s solidification zones to fill fractures formed by sag/collapse of roof-side solidification zones. MELTS software crystallization (at fO2 FMQ) of the sill magma (marginal chill zone as proxy), mass balance by linear regression, and Rayleigh fractionation all show that diorite forms after ∼72% at ∼1070°C but that it only generally resembles the diorite veins. Compositions that more fully resemble the actual segregations appear to require more than fractional crystallization, such as dioritic liquids admixed with up to ∼10% of the minerals in assemblages they crystallize. That is, evolved interstitial liquids produced from ∼70%–75% crystallization (e.g., SiO2 ∼60–65 wt%) over a volume of solidification zone framework and purged into fractures to crystallize “dioritic” pyroxene and plagioclase can produce varying diorite compositions and modes from place to place by admixing, a liquid-crystal process reasonable to expect for liquids purged into fractures.}, number={2}, journal={JOURNAL OF GEOLOGY}, author={Fodor, R. V.}, year={2009}, month={Mar}, pages={109–125} }
 @article{mccarter_fodor_trusdell_2006, title={Perspectives on basaltic magma crystallization and differentiation: Lava-lake blocks erupted at Mauna Loa volcano summit, Hawaii}, volume={90}, ISSN={["0024-4937"]}, DOI={10.1016/j.lithos.2006.03.005}, abstractNote={Explosive eruptions at Mauna Loa summit ejected coarse-grained blocks (free of lava coatings) from Moku'aweoweo caldera. Most are gabbronorites and gabbros that have 0–26 vol.% olivine and 1–29 vol.% oikocrystic orthopyroxene. Some blocks are ferrogabbros and diorites with micrographic matrices, and diorite veins (≤ 2 cm) cross-cut some gabbronorites and gabbros. One block is an open-textured dunite. The MgO of the gabbronorites and gabbros ranges ∼ 7–21 wt.%. Those with MgO > 10 wt.% have some incompatible-element abundances (Zr, Y, REE; positive Eu anomalies) lower than those in Mauna Loa lavas of comparable MgO; gabbros (MgO < 10 wt.%) generally overlap lava compositions. Olivines range Fo83–58, clinopyroxenes have Mg#s ∼ 83–62, and orthopyroxene Mg#s are 84–63 — all evolved beyond the mineral-Mg#s of Mauna Loa lavas. Plagioclase is An75–50. Ferrogabbro and diorite blocks have ∼ 3–5 wt.% MgO (TiO2 3.2–5.4%; K2O 0.8–1.3%; La 16–27 ppm), and a diorite vein is the most evolved (SiO2 59%, K2O 1.5%, La 38 ppm). They have clinopyroxene Mg#s 67–46, and plagioclase An57–40. The open-textured dunite has olivine ∼ Fo83.5. Seven isotope ratios are 87Sr/86Sr 0.70394–0.70374 and 143Nd/144Nd 0.51293–0.51286, and identify the suite as belonging to the Mauna Loa system. Gabbronorites and gabbros originated in solidification zones of Moku'aweoweo lava lakes where they acquired orthocumulate textures and incompatible-element depletions. These features suggest deeper and slower cooling lakes than the lava lake paradigm, Kilauea Iki, which is basalt and picrite. Clinopyroxene geobarometry suggests crystallization at < 1 kbar P. Highly evolved mineral Mg#s, < 75, are largely explained by cumulus phases exposed to evolving intercumulus liquids causing compositional ‘shifts.’ Ferrogabbro and diorite represent segregation veins from differentiated intercumulus liquids filter pressed into rigid zones of cooling lakes. Clinopyroxene geobarometry suggests < 300 bar P. Open-textured dunite represents olivine-melt mush, precursor to vertical olivine-rich bodies (as in Kilauea Iki). Its Fo83.5 identifies the most primitive lake magma as ∼ 8.3 wt.% MgO. Mass balancing and MELTS show that such a magma could have yielded both ferrogabbro and diorite by ≥ 50% fractional crystallization, but under different fO2: < FMQ (250 bar) led to diorite, and FMQ (250 bar) yielded ferrogabbro. These segregation veins, documented as similar to those of Kilauea, testify to appreciable volumes of ‘rhyolitic’ liquid forming in oceanic environments. Namely, SiO2-rich veins are intrinsic to all shields that reached caldera stage to accommodate various-sized cooling, differentiating lava lakes.}, number={3-4}, journal={LITHOS}, author={McCarter, Renee' L. and Fodor, R. V. and Trusdell, Frank}, year={2006}, month={Sep}, pages={187–213} }
 @article{huang_frey_blichert-toft_fodor_bauer_xu_2005, title={Enriched components in the Hawaiian plume: Evidence from Kahoolawe Volcano, Hawaii}, volume={6}, ISSN={["1525-2027"]}, DOI={10.1029/2005gc001012}, abstractNote={The geochemical differences between individual Hawaiian shields provide clues to the magma source components in the Hawaiian plume. Lavas from Koolau (Makapuu‐stage) and Kahoolawe volcanoes define the enriched, i.e., relatively high 87Sr/86Sr and low 143Nd/144Nd, extreme for Hawaiian shield lavas. There are, however, important geochemical differences between these shields; Kahoolawe lavas lack the relatively high SiO2, low CaO, and high Sr/Nb and La/Nb that are characteristic of Makapuu‐stage Koolau lavas, and they are offset from other Hawaiian shield lavas to high 87Sr/86Sr at a given 143Nd/144Nd. Consequently, a varying role for recycled plagioclase‐rich gabbro is inferred, in particular, lower amounts of the low 87Sr/86Sr component in Kahoolawe lavas. Also, lavas from Loa‐trend volcanoes, such as Kahoolawe, define trends ranging toward high 208Pb*/206Pb* and 87Sr/86Sr and low 143Nd/144Nd and 176Hf/177Hf. Such trends are consistent with variable amounts of recycled sediment sampled by Loa‐trend volcanoes, with the largest proportion in Makapuu‐stage Koolau lavas. Therefore the enriched component in the Hawaiian plume, the Koolau component, is recycled oceanic crust, which is heterogeneous because of varying proportions of sediment, basalt, and gabbro. Hawaiian shield‐stage lavas range widely in 87Sr/86Sr, 143Nd/144Nd, 176Hf/177Hf, and 206Pb/204Pb, but they have similar ratios of Sr/Nd, Nd/Hf, and Hf/Pb, each varying by a factor of <3 among the Hawaiian shields. This observation has important consequences. Namely, the similar Hf/Pb ratios are inconsistent with a two‐component (i.e., Kea and Koolau) mixing model for explaining the hyperbolic trend of 176Hf/177Hf versus 206Pb/204Pb defined by shield lavas. Such a model requires end‐members with very different Hf/Pb (a factor of 15 to 40), but this is not observed; therefore a third component must be involved. On the basis of trends of 208Pb*/206Pb* versus 87Sr/86Sr, 143Nd/144Nd, and 176Hf/177Hf, we infer that Loa and Kea trend shield lavas contain variable amounts of the Loihi source component.}, journal={GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS}, author={Huang, SC and Frey, FA and Blichert-Toft, J and Fodor, RV and Bauer, GR and Xu, GP}, year={2005}, month={Nov} }
 @article{weinstein_fodor_bauer_2004, title={Koolau shield basalt as xenoliths entrained during rejuvenated-stage eruptions: perspectives on magma mixing}, volume={66}, ISSN={["1432-0819"]}, DOI={10.1007/s00445-003-0302-1}, number={2}, journal={BULLETIN OF VOLCANOLOGY}, author={Weinstein, JP and Fodor, RV and Bauer, GR}, year={2004}, month={Feb}, pages={182–199} }
 @article{fodor_sial_gandhok_2002, title={Petrology of spinel peridotite xenoliths from northeastern Brazil: lithosphere with a high geothermal gradient imparted by Fernando de Noronha plume}, volume={15}, ISSN={["0895-9811"]}, DOI={10.1016/S0895-9811(02)00032-9}, abstractNote={Spinel lherzolite, harzburgite, and clinopyroxenite xenoliths and pyroxene megacrysts in Tertiary alkalic basalts of northeastern Brazil (∼30–13 Ma; K–Ar ages) provide information about melting, metasomatism, and geothermal gradients in subcontinental lithosphere as related to magmatism in that region since the Atlantic opening. That magmatism includes the xenoliths' host basalts, which have origins with the Fernando de Noronha plume, and regional tholeiitic basalts emplaced during continental rifting beginning ∼200 Ma. Peridotite textures are largely protogranular, but some are porphyroclastic. Mineral compositions show correlations among Mg#s, Cr#s, and pyroxene Cr2O3, Al2O3, and Na2O which suggest an upper-mantle history of varying melting and basalt extraction. Pyroxene equilibration temperatures range from ∼800–1250 °C and represent a high geotherm, ∼70–80 mW/m2, or ∼12 °C/km across the spinel stability field. Porphyroclastic xenoliths have the highest equilibration temperatures, >1150 °C. The equilibration temperatures do not correlate with the peridotite melting indicators (e.g. Cr#s; Cr2O3). In addition, Fe and Ti enrichments in minerals of porphyroclastic xenoliths, and light rare-earth element (LREE) enrichments, greatest in protogranular xenoliths (e.g. La(n) 2–16), each identify a metasomatic history for northeastern Brazil lithosphere. Several of these xenolith features, particularly the geotherm they represent, can be linked to the Fernando de Noronha hotspot during Tertiary. The high geotherm likely originated as northeastern Brazil ‘passed’ over the plume. It was overprinted on subcontinental lithospheric mantle with existing melting characteristics that were possibly acquired during the earlier magmatism (e.g. Mesozoic) that attended the opening of the central Atlantic. The clinopyroxenite and the pyroxene megacrysts coexisting with the peridotite xenoliths likely represent Fernando de Noronha plume-derived basaltic melts that veined deformed lithosphere near plume margins to locally metasomatize that peridotite (porphyroclastic) with Fe and Ti. The LREE enrichments are probably also largely attributable to the plume, from which small percentage melts metasomatized the lithosphere to varying degrees, particularly the ‘cooler’, shallower level (protogranular) peridotite.}, number={2}, journal={JOURNAL OF SOUTH AMERICAN EARTH SCIENCES}, author={Fodor, RV and Sial, AN and Gandhok, G}, year={2002}, month={Jun}, pages={199–214} }
 @article{fodor_2001, title={The role of tonalite and diorite in Mauna Kea volcano, Hawaii, magmatism: Petrology of summit-region leucocratic xenoliths}, volume={42}, ISSN={["0022-3530"]}, DOI={10.1093/petrology/42.9.1685}, abstractNote={anomaly and poikilitic texture indicate a cumulate origin. Leucocratic diorite (>50–53 wt % SiO2; 1–2·4 wt % K2O) xenoliths coexist with the tonalite. These have intergranular andesine–oligoclase (>68–85 vol. % of An50–15), evolved clinopyroxene (mg-number}, number={9}, journal={JOURNAL OF PETROLOGY}, author={Fodor, RV}, year={2001}, month={Sep}, pages={1685–1704} }
 @article{fodor_hanan_2000, title={Geochemical evidence for the Trindade hotspot trace: Columbia seamount ankaramite}, volume={51}, ISSN={["0024-4937"]}, DOI={10.1016/S0024-4937(00)00002-5}, abstractNote={The Columbia seamount ∼825 km offshore from Brazil at ∼20°S lies on the east–west ‘trace’ of the Trindade hotspot. Continental and oceanic magmatism believed to have originated with this hotspot is alkalic and SiO2-undersaturated, and dates from ∼85 Ma in southern Brazil to <3 Ma on the islands of Trindade and Martin Vaz ∼1100 km offshore. An ankaramite (clinopyroxene ∼16 vol%) dredged from Columbia seamount (est. 10 Ma) conforms to this geochemistry with SiO2-undersaturated Al-rich clinopyroxene (8–13 wt.% Al2O3) and rhönite. Clinopyroxene isotopic compositions are 87Sr/86Sr=0.703900, 143Nd/144Nd=0.512786, 206Pb/204Pb=19.190, 207Pb/204Pb=15.045, and 208Pb/204Pb=39.242 — resembling those for Trindade, except for slightly higher 207Pb/204Pb. The isotopic composition and abundance ratios among weathering-resistant Nb, La, and Yb suggest that Columbia seamount magmatism represents the present-day Trindade plume, but ∼10 million years earlier and perhaps when the plume manifested a signature of ‘contamination’ from subducted sediments. The Columbia seamount analyses provide the first quantitative assessment for the Trindade hotspot trace existing between the Brazil margin and Trindade, strengthening the case for a continuum of magmatism extending from the ∼85 Ma Brazilian igneous provinces of Poxoréu and Alto Paranaiba.}, number={4}, journal={LITHOS}, author={Fodor, RV and Hanan, BB}, year={2000}, month={Jun}, pages={293–304} }
 @article{fodor_2000, title={Plagioclase of Hawaiian tholeiitic and alkalic magma parentages: distinctions based on REE, Sr, Ba, Hf, and Ta}, volume={69}, ISSN={["0930-0708"]}, DOI={10.1007/s007100070022}, number={3-4}, journal={MINERALOGY AND PETROLOGY}, author={Fodor, RV}, year={2000}, pages={213–225} }
 @article{fodor_bauer_jacobs_1998, title={Alkalic magma modified by incorporation of diverse tholeiitic components: 'complex' hybridization on Kahoolawe island, Hawaii}, volume={63}, ISSN={["0930-0708"]}, DOI={10.1007/BF01162769}, number={1-2}, journal={MINERALOGY AND PETROLOGY}, author={Fodor, RV and Bauer, GR and Jacobs, RS}, year={1998}, pages={73–94} }
 @article{fodor_mukasa_sial_1998, title={Isotopic and trace-element indications of lithospheric and asthenospheric components in Tertiary alkalic basalts, northeastern Brazil}, volume={43}, ISSN={["0024-4937"]}, DOI={10.1016/S0024-4937(98)00012-7}, abstractNote={Plate reconstructions at 30 Ma place northeastern Brazil over the Fernando de Noronha hotspot, presently ∼250 km offshore northeastern Brazil. Tertiary basaltic centers in northeastern Brazil may therefore be products of the Fernando de Noronha hotspot. We examined alkalic basalt from seven ∼30–13 Ma old centers in Rio Grande do Norte and Pernambuco states to assess this possible link. Compositions are primitive, where MgO concentrations range from 12.5 to 17 wt.%, and SiO2 from ∼41 to 48 wt.%. Trace-element abundances and Sr, Nd, and Pb isotopic compositions compare well with those of ocean island basalt: 87Sr/86Sr=∼0.7038–0.7051, 143Nd/144Nd=∼0.51266–0.51280, and 206Pb/204Pb=∼18.52–19.35. There are correlations among SiO2-undersaturation, incompatible-element abundances, relative percentages of partial melting (based on La/Yb and La/Y ratios), and the degree of isotopic `enrichment' inherited from mantle sources. There is also a negative correlation for La/Nb (∼0.6–0.86) vs. Ba/Nb (6.6–10.6), where lower La/Nb samples represent larger percentages of melting of a source comparatively enriched in radiogenic Sr. We attribute these compositional relationships to the lavas representing mixing of melts mainly from asthenosphere of largely HIMU plus DM characterization, probably the Fernando de Noronha plume, with melts from subcontinental lithosphere that was isotopically closer to EM1. Isotopic and trace-element compositions of the northeastern Brazil basalts are generally similar to those of Fernando de Noronha lavas (12–2 Ma), and some minor trace-element differences observed (e.g., more Zr, Nb, and less Th compared to northeastern Brazil basalts) are probably due to heterogeneity within the asthenospheric plume and to melt contributions from delaminated subcontinental lithosphere that may underlie Fernando de Noronha.}, number={4}, journal={LITHOS}, author={Fodor, RV and Mukasa, SB and Sial, AN}, year={1998}, month={Sep}, pages={197–217} }
 @article{fodor_galar_1997, title={A view into the subsurface of Mauna Kea volcano, Hawaii: Crystallization processes interpreted through the petrology and petrography of gabbroic and ultramafic xenoliths}, volume={38}, ISSN={["0022-3530"]}, DOI={10.1093/petrology/38.5.581}, abstractNote={Xenoliths from the southern flank of Mauna Kea volcano form two broad categories. (1) Ultramafic: porphyroclastic dunite, wehrlite, and olivine clinopyroxenite (Fo89.4–83.6, clinopyroxene mg-number 90.3–86.3, spinel mg-number 57–42, spinel cr-number 7–52, no palgioclase); and granular wehrlite and olivine clinopyroxenite (Fo83–76) with plagioclase (An84–69) ± orthopyroxene, and Cr-magnetite. (2) Gabbroic: granular gabbro, gabbronorite, and troctolite composed of olivine + clinopyroxene frameworks (Fo82–74, mg-number 85–79) enclosing plagioclase (∼An79–69) ±orthopyroxene, and Fe–Ti oxides; and plagioclase (<An77) forming frameworks for, and fine-grained mosaics with, evolved olivine (Fo75–61), clinopyroxene±orthopyroxene, and Fe–Ti oxides. Most xenoliths are petrographically uniform, but some manifest modal, phase, cryptic, or grain-size layering, and some are composites of two rock types. Whole-xenolith incompatible elements are ‘depleted’, and there are positive Eu anomalies; 87Sr/86Sr is 0.70360, and mineral δ18O is 4.05–5.62. Porphyroclastic ultramafic xenoliths are gravity-settled and in situ cumulates from reservoir bottoms. Plagioclase-bearing xenoliths represent modal, phase, and cryptic layering (e.g. wehrlite to gabbronorite) in reservoir-margin solidification zones superimposed with small-scale (centimeter) modal, cryptic, phase, and grain-size layering. Mineral compositions point to tholeiitic parentage for most xenoliths, but alkalic for some (e.g. clinopyroxene (Al2O3 >4 wt %). These Mauna Kea xenoliths are plutonic complements to postshield lavas (Hamakua volcanics), and they identify that stage of volcano development with 15–5 wt % MgO magmas that underwent processes intrinsic to mafic-layered intrusions; e.g. in situ and gravity-settled crystallization, extensive differentiation, varieties of layering, mobilizations of late-stage, evolved liquids, compaction and connective disturbances in reservoirs.}, number={5}, journal={JOURNAL OF PETROLOGY}, author={Fodor, RV and Galar, P}, year={1997}, month={May}, pages={581–624} }
 @article{hoover_fodor_1997, title={Magma-reservoir crystallization processes: small-scale dikes in cumulate gabbros, Mauna Kea Volcano, Hawaii}, volume={59}, ISSN={["0258-8900"]}, DOI={10.1007/s004450050185}, number={3}, journal={BULLETIN OF VOLCANOLOGY}, author={Hoover, SR and Fodor, RV}, year={1997}, month={Dec}, pages={186–197} }
 @article{kosecki_fodor_1997, title={Petrology, mineralogy and geochemistry of the Rolesville Granitic Batholith, Eastern Piedmont, North Carolina}, volume={37}, number={2}, journal={Southeastern Geology}, author={Kosecki, J. and Fodor, R. V.}, year={1997}, pages={91-} }
 @book{fodor_1989, title={Gold, copper, iron how metals are formed, found, and used}, publisher={Hillside, NJ, USA: Enslow Publishers}, author={Fodor, R.V.}, year={1989} }