82 results on '"Matthew A. Coble"'
Search Results
2. Magmatic Processes at Snæfell Volcano, Iceland, Constrained by Zircon Ages, Isotopes, and Trace Elements
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Tenley J. Banik, Tamara L. Carley, Matthew A. Coble, John M. Hanchar, Justin P. Dodd, Gabriele M. Casale, and Sean P. McGuire
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Hf isotopes ,O isotopes ,Snæfell ,U‐Pb geochronology ,zircon ,Geophysics. Cosmic physics ,QC801-809 ,Geology ,QE1-996.5 - Abstract
Abstract We present the first zircon‐based U‐Pb geochronology, trace element concentrations, and O and Hf isotope compositions for Snæfell, an off‐rift volcano in eastern Iceland. These data provide constraints on the longevity and petrogenetic conditions of the Snæfell magmatic system. U‐Pb zircon ages range from 545 ± 59 to 266 ± 16 ka (2SE), but differences between grain core and mantle ages within each sample reveal zircon residence times of 100–200 kyr—far longer than observed at other Neovolcanic systems in Iceland. Zircon δ18O is restricted to ∼3.5–4‰, and zircon εHf ranges ∼+13 to ∼+17, which is substantially more radiogenic than Snæfell basalts. This combined O and Hf isotopic perspective suggests rhyolite petrogenesis at Snæfell can be attributed to fractional crystallization of mantle‐derived basaltic magmas with limited influence of pre‐existing crustal material. Trace element evidence further characterizes the magmatic source material: Sc/Yb
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- 2021
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3. Lithium enrichment in intracontinental rhyolite magmas leads to Li deposits in caldera basins
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Thomas R. Benson, Matthew A. Coble, James J. Rytuba, and Gail A. Mahood
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Science - Abstract
Lithium is increasingly being utilized for modern technology in the form of lithium-ion batteries. Here, using in situ measurements of quartz-hosted melt inclusions, the authors demonstrate that preserved lake sediments within rhyolitic calderas have the potential to host large lithium-rich clay deposits.
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- 2017
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4. Post-supereruption recovery at Toba Caldera
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Adonara E. Mucek, Martin Danišík, Shanaka L. de Silva, Axel K. Schmitt, Indyo Pratomo, and Matthew A. Coble
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Science - Abstract
Toba Caldera in Indonesia had one of the largest volcanic eruptions over the last 100 kyr and has since undergone periods of resurgence. Here, the authors present zircon and sediment age data showing resurgence started after the climactic eruption and lasted until 2.7 ka, advancing west and south.
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- 2017
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5. Geochronological and Geochemical Study of Zircon from Tourmaline-Muscovite Granites of the Archaean Kolmozero–Voronya Greenstone Belt: Insights into Sources of the Rare-Metal Pegmatites
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Nikolay M. Kudryashov, Oksana V. Udoratina, Matthew A. Coble, and Ekaterina N. Steshenko
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Archaean tourmaline-muscovite granite ,U-Pb (SHRIMP) zircon ,Kolmozero spodumene pegmatite deposit ,Kola Peninsula ,Mineralogy ,QE351-399.2 - Abstract
In order to determine the U-Pb crystallization age of zircon from the tourmaline-muscovite granites of the Kolmozero–Voronya greenstone belt located in the northeastern Fennoscandian Shield (Kola Peninsula), an isotope-geochronological study of the zircon grains was performed using a SHRIMP-RG microprobe. The belt is represented by the Archaean volcano-sedimentary rocks (2.9–2.8 Ga). Deposits of rare-metal pegmatites (Li and Cs with associated Nb, Ta, and Be) occur within the belt and on its margins. The age of the pegmatites within the belt was estimated at 2.7–2.6 Ga. Until now, there has been no generally accepted view on the genetic relation of the pegmatites with granite. Various authors have suggested that the pegmatites could potentially be associated with many type of granitoids within the region, i.e., plagiogranites, tonalites, amphibole-biotite granodiorites, microcline granites, alkaline granites, or muscovite-tourmaline granites. Zircon crystals from the muscovite-tourmaline granites are heterogeneous; they have less altered cores and strongly altered rims. The zircon cores are slightly enriched in U at a value of 173–1030 ppm, Th/U = 0.1–0.4. The zircons’ rims are heavily enriched in U at a value of 700–3300 ppm, Th/U = 0.03–0.08, indicating metasomatic processes. Zircon characteristics show that it crystallized from a melt enriched in a fluid phase. Fluid activity lasted after zircon crystallization as reflected in the irregular composition of the mineral and its rare earth element (REE) patterns that are typical of a metasomatic zircon. The computed zircon crystallization temperature in the tourmaline-muscovite granites is in the range of 650–850 °C. The discordant age calculated for five analyzed points of the zircon crystal cores is 2802 ± 13 Ma. The discordant age for four analyzed points of the zircon crystal rims is found to be 2728 ± 14 Ma. On the basis of the obtained isotope-geochronological data, we conclude that the tourmaline-muscovite granites located in the immediate vicinity of rare-metal pegmatite veins are the most probable source of matter for the pegmatites.
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- 2020
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6. Petrogenesis and geodynamic evolution in the northern Westfjords, Iceland, elucidated by Iceland’s oldest silicic rocks
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Tenley J. Banik, Matthew A. Coble, Calvin F. Miller, Christopher M. Fisher, Brennan T. Jordan, Jeffrey D. Vervoort, and Tamara L. Carley
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Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) - Published
- 2023
7. Metamorphism of the Sierra de Maz and implications for the tectonic evolution of the MARA terrane
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Patricia Webber, Emily Houlihan, Sean R. Mulcahy, Vinicius T. Meira, William C. McClelland, Matthew A. Coble, Jeffrey D. Vervoort, Andrew Tholt, and Sarah M. Roeske
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Tectonics ,Stratigraphy ,Geochemistry ,Metamorphism ,Geology ,Terrane - Abstract
The Mesoproterozoic MARA terrane of western South America is a composite igneous-metamorphic complex that is important for Paleozoic paleogeographic reconstructions and the relative positions of Laurentia and Gondwana. The magmatic and detrital records of the MARA terrane are consistent with a Laurentian origin; however, the metamorphic and deformation records lack sufficient detail to constrain the correlation of units within the MARA terrane and the timing and mechanisms of accretion to the Gondwana margin. Combined regional mapping, metamorphic petrology, and garnet and monazite geochronology from the Sierra de Maz of northwest Argentina suggest that the region preserves four distinct litho-tectonic units of varying age and metamorphic conditions that are separated by middle- to lower-crustal ductile shear zones. The Zaino and Maz Complexes preserve Barrovian metamorphism and ages that are distinct from other units within the region. The Zaino and Maz Complexes both record metamorphism ca. 430–410 Ma and show no evidence of the regional Famatinian orogeny (ca. 490–455 Ma). In addition, the Maz Complex records an earlier granulite facies event at ca. 1.2 Ga. The Taco and Ramaditas Complexes, in contrast, experienced medium- and low-pressure upper amphibolite to granulite facies metamorphism, respectively, between ca. 470–460 Ma and were later deformed at ca. 440–420 Ma. The Maz shear zone that bounds the Zaino and Maz Complexes records sinistral oblique to sinistral deformation between ca. 430–410 Ma. The data suggest that at least some units in the MARA terrane were accreted by translation, and the Gondwana margin of northwest Argentina transitioned from a dominantly convergent margin to a highly oblique margin in the Silurian.
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- 2021
8. The timing of rifting events in the easternmost Mediterranean: U-Pb dating of zircons from volcanic rocks in the Levant margin
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Tzahi Golan, Yaron Katzir, and Matthew A. Coble
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Volcanic rock ,Basalt ,Mediterranean climate ,geography ,Rift ,geography.geographical_feature_category ,Magmatism ,Geochemistry ,Geology ,Subsidence ,Extensional definition ,Zircon - Abstract
Continental rifting settings are characterized by differential uplift and subsidence, extensive sedimentation and magmatism of variable, mostly basaltic, composition. Extensional stresses activate ...
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- 2021
9. P–T–t Path of Unusual Garnet–Kyanite–Staurolite– Amphibole Schists, Ellesmere Island, Canada—Quartz Inclusion in Garnet Barometry and Monazite Petrochronology
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Karolina Kośmińska, Jane A Gilotti, William C McClelland, Matthew A Coble, and Jay B Thomas
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Geophysics ,Geochemistry and Petrology - Abstract
Garnet–kyanite–staurolite assemblages with large, late porphyroblasts of amphibole form garbenschists in Ordovician volcaniclastic rocks lying immediately south of the Pearya terrane on northernmost Ellesmere Island, Canada. The schist, which together with carbonate olistoliths makes up the Petersen Bay Assemblage (PBA), displays a series of parallel isograds that mark an increase in metamorphic grade over a distance of 10 km towards the contact with Pearya; however, a steep, brittle Cenozoic strike-slip fault with an unknown amount displacement disturbs the earlier accretionary relationship. The late amphibole growth, probably due to fluid ingress, is clear evidence of disequilibrium conditions in the garbenschist. In order to recover the P–T history of the schists, we construct isochemical phase equilibrium models for a nearby garnet–mica schist that escaped the fluid event and compare the results to quartz inclusion in garnet (QuiG) barometry for a garbenschist and the metapelitic garnet schist. Quartz inclusions are confined to garnet cores and the QuiG results, combined with Ti-in-biotite and garnet–biotite thermometry, delineate a prograde path from 480 to 600°C and 0.7 to 0.9 GPa. This path agrees with growth zoning in garnet deduced from X-ray maps of the spessartine component in garnet. The peak conditions obtained from pseudosection modelling using effective bulk composition and the intersection of garnet rim with matrix biotite and white mica isopleths in the metapelite are 665°C at ≤0.85 GPa. Three generations of monazite (I, II and III) were identified by textural characterization, geochemical composition (REE and Y concentrations) and U–Pb ages measured by ion microprobe. Monazite I occurs in the matrix and as inclusions in garnet rims and grew at peak P–T conditions at 397 ± 2 Ma (2σ) from the breakdown of allanite. Monazite II forms overgrowths on matrix Monazite I grains that are oriented parallel to the main schistosity and yield ages of 385 ± 2 Ma. Monazite III, found only in the garbenschist, is 374 ± 6 Ma, which is interpreted as the time of amphibole growth during fluid infiltration at lower temperature and pressure on a clockwise P–T path that remained in the kyanite stability field. These results point to a relatively short (≈12 Myr) Barrovian metamorphic event that affected the schists of the PBA. An obvious heat source is lacking in the adjacent Pearya terrane, but we speculate it was large Devonian plutons—similar to the 390 ± 10 Ma Cape Woods granite located 40 km across strike from the fault—that have been excised by strike-slip. Arc fragments that are correlative to the PBA are low grade; they never saw the heat and were not directly involved in Pearya accretion.
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- 2022
10. Siliceous subglacial deposits: archives of subglacial processes during the Last Glacial Maximum
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Bernard Hallet, Matthew A. Coble, Terrence Blackburn, Shalev Siman-Tov, and Emily E. Brodsky
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geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Bedrock ,Andesite ,Geochemistry ,Weathering ,Last Glacial Maximum ,Glacier ,010502 geochemistry & geophysics ,01 natural sciences ,Geologic time scale ,Erosion ,Lithification ,Geology ,0105 earth and related environmental sciences ,Earth-Surface Processes - Abstract
We report detailed chemical and isotopic data from a subglacial siliceous deposit on andesitic bedrock recently exposed by glacier retreat. Whereas a single
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- 2021
11. Crustal Forensics at Pūtauaki (Mt. Edgecumbe), New Zealand reveal the influence of deep crustal arc processes on magma evolution in the Taupo Volcanic Zone
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Dale H. Burns, Shanaka L. de Silva, Phil Shane, and Matthew A. Coble
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Geophysics ,Geochemistry and Petrology - Published
- 2022
12. Interplay of Cretaceous transpressional deformation and continental arc magmatism in a long-lived crustal boundary, central Fiordland, New Zealand
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Elena Miranda, Andrew R.C. Kylander-Clark, R.E. Turnbull, Matthew A. Coble, Joshua J. Schwartz, Keith A. Klepeis, R. Jongens, and Hannah J. Blatchford
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Paleontology ,010504 meteorology & atmospheric sciences ,Stratigraphy ,Magmatism ,Boundary (topology) ,Geology ,Deformation (meteorology) ,010502 geochemistry & geophysics ,01 natural sciences ,Cretaceous ,0105 earth and related environmental sciences ,Continental arc - Abstract
Recovering the time-evolving relationship between arc magmatism and deformation, and the influence of anisotropies (inherited foliations, crustal-scale features, and thermal gradients), is critical for interpreting the location, timing, and geometry of transpressional structures in continental arcs. We investigated these themes of magma-deformation interactions and preexisting anisotropies within a middle- and lower-crustal section of Cretaceous arc crust coinciding with a Paleozoic boundary in central Fiordland, New Zealand. We present new structural mapping and results of Zr-in-titanite thermometry and U-Pb zircon and titanite geochronology from an Early Cretaceous batholith and its host rock. The data reveal how the expression of transpression in the middle and lower crust of a continental magmatic arc evolved during emplacement and crystallization of the ∼2300 km2 lower-crustal Western Fiordland Orthogneiss (WFO) batholith. Two structures within Fiordland’s architecture of transpressional shear zones are identified. The gently dipping Misty shear zone records syn-magmatic oblique-sinistral thrust motion between ca. 123 and ca. 118 Ma, along the lower-crustal WFO Misty Pluton margin. The subhorizontal South Adams Burn thrust records mid-crustal arc-normal shortening between ca. 114 and ca. 111 Ma. Both structures are localized within and reactivate a recently described >10 km-wide Paleozoic crustal boundary, and show that deformation migrated upwards between ca. 118 and ca. 114 Ma. WFO emplacement and crystallization (mainly 118–115 Ma) coincided with elevated (>750 °C) middle- and lower-crustal Zr-in-titanite temperatures and the onset of mid-crustal cooling at 5.9 ± 2.0 °C Ma−1 between ca. 118 and ca. 95 Ma. We suggest that reduced strength contrasts across lower-crustal pluton margins during crystallization caused deformation to migrate upwards into thermally weakened rocks of the mid-crust. The migration was accompanied by partitioning of deformation into domains of arc-normal shortening in Paleozoic metasedimentary rocks and domains that combined shortening and strike-slip deformation in crustal-scale subvertical, transpressional shear zones previously documented in Fiordland. U-Pb titanite dates indicate Carboniferous–Cretaceous (re)crystallization, consistent with reactivation of the inherited boundary. Our results show that spatio-temporal patterns of transpression are influenced by magma emplacement and crystallization and by the thermal structure of a reactivated boundary.
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- 2020
13. Characterization of the rhyolite of Bodie Hills and 40Ar/39Ar intercalibration with Ar mineral standards
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David A. John, M. C. van Soest, Robert J. Fleck, Leslie A. Hayden, Joseph L. Wooden, Matthew A. Coble, Andrew T. Calvert, Kip V. Hodges, and Edward A. du Bray
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Radiogenic nuclide ,010504 meteorology & atmospheric sciences ,Geochemistry ,Geology ,engineering.material ,010502 geochemistry & geophysics ,Sanidine ,01 natural sciences ,Thermochronology ,Igneous rock ,Geochemistry and Petrology ,Geochronology ,Rhyolite ,engineering ,Biotite ,0105 earth and related environmental sciences ,Zircon - Abstract
The rhyolite of Bodie Hills (California) is characterized compositionally and the geochronology of selected phases is studied. Sanidine (BHs) from the rhyolite is well suited as a 40Ar/39Ar reference material with high K/Ca and radiogenic yield. Intercalibration with GA1550 biotite from the Dromedary igneous complex (New South Wales, Australia) yields an age of 9.7946 ± 0.0031 Ma for BHs relative to an age of 98.79 ± 0.54 Ma for GA1550 and a calibration factor (RBHs/GA1550) of 0.096719 ± 0.000032. BHs is also intercalibrated with sanidines of the Taylor Creek Rhyolite (TCs; RTCs/BHs of 2.90874 ± 0.00067), Fish Canyon Tuff (FCs; RFCs/BHs of 2.88339 ± 0.00088), and rhyolite of Alder Creek (ACs; RACs/BHs of 0.12028 ± 0.00024). These calibration factors yield ages of 28.344 ± 0.011 Ma, 28.099 ± 0.013 Ma, and 1.1809 ± 0.0024 Ma for TCs, FCs, and ACs, respectively, relative to GA1550. Full propagation of errors increases these uncertainties and that of BHs to ±0.9% of their ages. Calibration of BHs using the astronomically tuned age of FCs determined by Kuiper et al. (2008) yields an age of 9.8295 ± 0.0036 Ma. Stepwise heating of BHs reveals the same small, progressive increase in age across the age spectrum reported for FCs, ACs, and other potassium feldspars (e.g., Foland and Xu, 1990; Phillips et al., 2017). This increase is consistent with mass fractionation of argon during step heating and favors use of single-step fusion ages of all sanidines for monitor and calibration purposes. Zircons from the rhyolite of Bodie Hills are strongly zoned in U and Th, and U/Pb geochronologic analyses suggest multiple generations of zircon growth. The youngest ages indicate a crystallization age of 9.97 ± 0.08 Ma (2σ); arguably similar to the 40Ar/39Ar results when residence time is considered, but previous episodes of zircon growth began at least 400 ka prior to eruption. Precise (U - Th)/He thermochronology of these zircons is difficult because crystal-to-crystal variations in the magnitude and complexity of their U + Th zoning complicates accurate alpha ejection calculations. Replicate conventional (single-crystal) (U - Th)/He ages are more widely dispersed than predicted by analytical uncertainties, but laser ablation (U - Th)/He ages are more reproducible, with an inverse variance-weighted mean of 9.71 ± 0.58 Ma.
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- 2019
14. Temporal and spatial variations in magmatism and transpression in a Cretaceous arc, Median Batholith, Fiordland, New Zealand
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Matthew A. Coble, Joshua J. Schwartz, Andrew R.C. Kylander-Clark, Elena Miranda, Andy J. Tulloch, Keith A. Klepeis, and Luisa F. Buritica
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Arc (geometry) ,Paleontology ,010504 meteorology & atmospheric sciences ,Batholith ,Magmatism ,Geology ,010502 geochemistry & geophysics ,01 natural sciences ,Transpression ,Cretaceous ,0105 earth and related environmental sciences - Abstract
We investigated the interplay between deformation and pluton emplacement with the goal of providing insights into the role of transpression and arc magmatism in forming and modifying continental arc crust. We present 39 new laser-ablation–split-stream–inductively coupled plasma–mass spectrometry (LASS-ICP-MS) and secondary ion mass spectrometry (SIMS) 206Pb/238U zircon and titanite dates, together with titanite geochemistry and temperatures from the lower and middle crust of the Mesozoic Median Batholith, New Zealand, to (1) constrain the timing of Cretaceous arc magmatism in the Separation Point Suite, (2) document the timing of titanite growth in low- and high-strain deformational fabrics, and (3) link spatial and temporal patterns of lithospheric-scale transpressional shear zone development to the Cretaceous arc flare-up event. Our zircon results reveal that Separation Point Suite plutonism lasted from ca. 129 Ma to ca. 110 Ma in the middle crust of eastern and central Fiordland. Deformation during this time was focused into a 20-km-wide, arc-parallel zone of deformation that includes previously unreported segments of a complex shear zone that we term the Grebe shear zone. Early deformation in the Grebe shear zone involved development of low-strain fabrics with shallowly plunging mineral stretching lineations from ca. 129 to 125 Ma. Titanites in these rocks are euhedral, are generally aligned with weak subsolidus fabrics, and give rock-average temperatures ranging from 675 °C to 700 °C. We interpret them as relict magmatic titanites that grew prior to low-strain fabric development. In contrast, deformation from ca. 125 to 116 Ma involved movement along subvertical, mylonitic shear zones with moderately to steeply plunging mineral stretching lineations. Titanites in these shear zones are anhedral grains/aggregates that are aligned within mylonitic fabrics and have rock-average temperatures ranging from ∼610 °C to 700 °C. These titanites are most consistent with (re)crystallization in response to deformation and/or metamorphic reactions during amphibolite-facies metamorphism. At the orogen scale, spatial and temporal patterns indicate that the Separation Point Suite flare-up commenced during low-strain deformation in the middle crust (ca. 129–125 Ma) and peaked during high-strain, transpressional deformation (ca. 125–116 Ma), during which time the magmatic arc axis widened to 70 km or more. We suggest that transpressional deformation during the arc flare-up event was an important process in linking melt storage regions and controlling the distribution and geometry of plutons at mid-crustal levels.
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- 2019
15. Ten-million years of activity within the Eastern California Shear Zone from U–Pb dating of fault-zone opal
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Perach Nuriel, Matthew A. Coble, Kate Maher, David M. Miller, and Kevin M. Schmidt
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geography ,Surface rupture ,geography.geographical_feature_category ,San andreas fault ,Fault (geology) ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Earthquake hazard ,Earth and Planetary Sciences (miscellaneous) ,Opaline silica ,Shear zone ,human activities ,Geology ,Seismology - Abstract
Reconstructions of long-term fault activity are essential for understanding both the mechanisms controlling fault behavior and accurate earthquake hazard assessments. Increasing evidence for temporal variations in strain accumulation suggests non-uniform strain rates over a range of historic to geologic timescales. The paucity of long-term records of fault activity has limited our ability to resolve these variations. We present a method for constraining long-term fault activity based on U–Pb dating of fault-related opal from secondary fault segments within the Eastern California Shear Zone (ECSZ). The presence of sheared and breccia-cemented opaline silica within well-exposed faults at near-surface conditions suggest that opal formation is associated with high-magnitude earthquakes capable of surface rupture (>6 M). Temporal constraints from massive and sheared syntectonic opal ( n = 74 ) on related secondary faults from this study provide new insights on the timing of fault initiation, reactivation, and longevity. The oldest dates obtained indicate that ECSZ activity commenced at or before 10 Ma. Multiple deformation events dated within a single structure on episodically deposited and sheared opal (up to six generations), demonstrate that fault reactivation occurred over 105 yr timescales (0.7–0.1 Myr). Relative probabilities of dated deformation events can be used to evaluate changes in fault activity in the past 2.5 Ma ( n = 60 ). This analysis indicates enhanced fault activity starting at 2 Ma and peaking around 1 Ma, possibly due to fault-interactions and distribution of deformation between the ECSZ and the San Andreas Fault.
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- 2019
16. Pre-Cenozoic evolution of the Aghil Range (western Tibetan Plateau): A missing piece of the Tibet-Pamir-Karakorum geopuzzle
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Franco Rolfo, William C. McClelland, Matthew A. Coble, and Chiara Groppo
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U-Pb geochronology ,geography ,Plateau ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Geology ,010502 geochemistry & geophysics ,petrology ,01 natural sciences ,Cretaceous ,Tibetian Plateau ,pre-cenozoic evolution ,Gondwana ,Precambrian ,Paleontology ,Basement (geology) ,Passive margin ,Geochronology ,Cimmerian orogeny ,0105 earth and related environmental sciences ,Terrane - Abstract
The Tibetan Plateau, largely derived from the accretion of several Gondwana microplates to the southern margin of Asia since the late Palaeozoic, is the highest and largest topographic relief on Earth. Although the first order geodynamic processes responsible for its pre-Cenozoic evolution are quite well-known, many issues are still debated, among which is the timing of collision of each terrane with the southern margin of Asia. Even more uncertain is the pre-Palaeozoic history of these terranes, due to the lack of basement exposures. As a contribution to understanding the pre-Cenozoic evolution of the Tibetan Plateau, this paper focuses on the Aghil Range, a remote and poorly investigated area close to the Karakorum Fault between Kunlun and Karakorum (Xinjiang, China) in western Tibet. The tectono-metamorphic and magmatic evolution of the Aghil Range is investigated using a multidisciplinary approach that combines field mapping, petrology and geochronology (U Pb on titanite, zircon, monazite and xenotime using SHRIMP-RG). We demonstrate that the Aghil Range preserves a coherent slice of Neoproterozoic crystalline basement with a late Palaeozoic sedimentary cover deposited on a passive continental margin during the Gondwana break-up. This represents the westernmost exposure of Precambrian crystalline basement known so far in the Tibetan Plateau. Furthermore, petrological and geochronological results allow reconstructing the Mesozoic poly-metamorphic evolution of this sector of the Tibetan Plateau, which records the evidence of Middle Jurassic (ca. 170 Ma) and Late Cretaceous (66 Ma) collisional events, as well as of the Late Jurassic (ca. 150 Ma) early subduction of an accretionary complex developed on its southern margin. Evidence of Late Cretaceous subduction-related magmatism preceding the last collisional event is also recorded. These results allow tentative correlation of the different terranes of Central Tibet with those of the Pamir-Karakorum Range on both sides of the Karakorum fault.
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- 2019
17. On the eruption age and provenance of the Old Crow tephra
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Michelle L. Coombs, Seth D. Burgess, Kristi L. Wallace, Matthew A. Coble, and Jorge A. Vazquez
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010506 paleontology ,Archeology ,Global and Planetary Change ,Provenance ,education.field_of_study ,010504 meteorology & atmospheric sciences ,Population ,Geochemistry ,Geology ,01 natural sciences ,Magma ,Geochronology ,Radiometric dating ,Tephra ,education ,Tephrochronology ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Zircon - Abstract
Tephrochronology is used to correlate and reconstruct geographically disparate sedimentary records of changing environment, climate, and landscape throughout geologic time. Single tephra layers represent isochronous markers across broad regions, thus accurate and precise radiometric constraints on the timing of eruption are critical to their utility. The Old Crow tephra is found throughout eastern Beringia and represents the largest preserved Pleistocene ashfall event in the region. Despite its volume and significance as a stratigraphic marker, the provenance of this tephra is debated, and the interpreted eruption age of marine isotope stage (MIS) 5 at ∼125 ka has vacillated. To investigate provenance and eruption age, we develop a geochemical fingerprint for the Old Crow tephra via titanomagnetite geochemistry, and zircon crystallization/cooling age via coupled U/Pb, U/Th, and (U Th)/He zircon geochronology. Our results indicate that Old Crow oxides are geochemically distinct from the commonly assumed source-caldera system at the Emmons Lake Volcanic Center (ELVC). Zircon crystals from the Old Crow tephra range in age from Proterozoic to Pleistocene, with concordant zircon U/Pb, U/Th, and (U Th)/He dates on the youngest population of grains suggesting crystallization in their parent magma, and in turn eruption, at 202.9 ± 9.5 ka. We discuss strengths and shortcomings of our radiogenic datasets in light of this result and review the far-reaching implications of a change in Old Crow eruption age.
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- 2019
18. Repeated Rhyolite Eruption From Heterogeneous Hot Zones Embedded Within a Cool, Shallow Magma Reservoir
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Matthew A. Coble, Brad S. Singer, and Nathan L. Andersen
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Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Rhyolite ,Magma ,Earth and Planetary Sciences (miscellaneous) ,Petrology ,Geology ,Zircon - Published
- 2019
19. Composition and formation age of amorphous silica coating glacially polished surfaces
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Greg M. Stock, Bernard Hallet, Terrence Blackburn, Shalev Siman-Tov, Matthew A. Coble, and Emily E. Brodsky
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Geochemistry & Geophysics ,010504 meteorology & atmospheric sciences ,Metallurgy ,Geology ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Coating ,Earth Sciences ,engineering ,Composition (visual arts) ,Amorphous silica ,Stock (firearms) ,0105 earth and related environmental sciences - Abstract
Author(s): Blackburn, Terrence; Siman-Tov, Shalev; Coble, Matthew A; Stock, Greg M; Brodsky, Emily E; Hallet, Bernard
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- 2019
20. In situ measurements of lead and other trace elements in abyssal peridotite sulfides
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Megan E. D’Errico, Jessica M. Warren, and Matthew A. Coble
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Abyssal zone ,Trace (semiology) ,Peridotite ,In situ ,Geophysics ,Lead (geology) ,Geochemistry and Petrology ,Geochemistry ,Geology - Published
- 2019
21. Magmatic Processes at Snæfell Volcano, Iceland, Constrained by Zircon Ages, Isotopes, and Trace Elements
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Gabriele Casale, Sean P. McGuire, John M. Hanchar, Tenley J. Banik, Tamara L. Carley, J. P. Dodd, and Matthew A. Coble
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Trace (semiology) ,geography ,Geophysics ,geography.geographical_feature_category ,Isotope ,Volcano ,Geochemistry and Petrology ,Geochemistry ,Geology ,Zircon - Published
- 2021
22. ISOTOPE-GEOCHRONOLOGICAL U-Pb (SHRIMP-RG) AND GEOCHEMICAL CHARACTERISTICS OF ZIRCON FROM RARE METAL (W, Li) APLITE GRANITE OF THE MURMANSK BLOCK
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Nikolai Kudryashov, Oksana Udoratina, Arkady Kalinin, Elena Galeeva, and Matthew A. Coble
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General Earth and Planetary Sciences ,General Environmental Science - Published
- 2022
23. The Origin of Plagiogranites: Coupled SIMS O Isotope Ratios, U–Pb Dating and Trace Element Composition of Zircon from the Troodos Ophiolite, Cyprus
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John W. Valley, Yaron Katzir, Kouki Kitajima, Tzahi Golan, Navot Morag, and Matthew A. Coble
- Subjects
Geophysics ,010504 meteorology & atmospheric sciences ,Isotope ,Geochemistry and Petrology ,Geochemistry ,Trace element composition ,Troodos Ophiolite ,010502 geochemistry & geophysics ,01 natural sciences ,Geology ,0105 earth and related environmental sciences ,Zircon - Abstract
U–Pb ages, trace element content and oxygen isotope ratios of single zircons from five plagiogranite intrusions of the Troodos ophiolite were measured to determine their crystallization age and assess the importance of fractional crystallization versus crustal anatexis in their petrogenesis. The results indicate that oceanic magmatism in Troodos took place at 94·3 ± 0·5 Ma, about 3 Myr earlier than previously recognized. Later hydrothermal alteration has affected most of the Troodos plagiogranitic rocks, resulting in growth of new zircon and/or partial alteration of zircon domains, causing slightly younger apparent crystallization ages. The new age inferred for seafloor spreading and ocean crust accretion in Troodos nearly overlaps that of the Semail ophiolite in Oman (95–96 Ma), strengthening previous indications for simultaneous evolution of both ophiolites in similar tectonic settings. Average δ18O(Zrn) values in the Troodos plagiogranites range between 4·2 and 4·8 ‰. The lower values in this range are lower than those expected in equilibrium with mantle-derived melt (5·3 ± 0·6 ‰), indicating variable contribution from hydrothermally altered, deep-seated oceanic crust in most of the Troodos plagiogranite intrusions. The inferred substantial involvement of crustal component is consistent with the existence of a shallow axial magma chamber, typical of fast-spreading mid-ocean ridge settings, within the Troodos slow-spreading ridge environment. This apparent contradiction may be reconciled by episodically intense magmatism within an otherwise slow, magmatically deprived spreading axis.
- Published
- 2020
24. Deformational temperatures across the Lesser Himalayan Sequence in eastern Bhutan and their implications for the deformation history of the Main Central Thrust
- Author
-
Dawn A. Kellett, David Whipp, Nicholas Whynot, Matthew A. Coble, Isabelle Coutand, Djordje Grujic, Kyle P. Larson, Kyle T. Ashley, Min Gao, and Department of Geosciences and Geography
- Subjects
1171 Geosciences ,SOUTH TIBETAN DETACHMENT ,CARBONACEOUS-MATERIAL ,010504 meteorology & atmospheric sciences ,AR-40/AR-39 GEOCHRONOLOGY ,THERMOCHRONOMETER COOLING AGES ,INVERTED BARROVIAN SEQUENCE ,EXTENSIONAL DETACHMENT ,Deformation (meteorology) ,010502 geochemistry & geophysics ,THERMAL STRUCTURE ,01 natural sciences ,C-AXIS FABRICS ,Thermochronology ,Sequence (geology) ,Paleontology ,Geophysics ,Geochemistry and Petrology ,Main Central Thrust ,CENTRAL NEPAL ,Shear zone ,SIKKIM HIMALAYA ,Geology ,0105 earth and related environmental sciences - Abstract
We postulate that the inverted metamorphic sequence in the Lesser Himalayan Sequence of the Himalayan orogen is a finite product of its deformation and temperature history. To explain the formation of this inverted metamorphic sequence across the Lesser Himalayan Sequence with a focus on the Main Central Thrust (MCT) in eastern Bhutan, we determined the metamorphic peak temperatures by Raman spectroscopy of carbonaceous material and established the deformation temperatures by Ti-in-quartz thermobarometry and quartz c axis textures. These data were combined with thermochronology, including new and published Ar-40/Ar-39 ages of muscovite and published apatite fission track, and apatite and zircon (U-Th)/He ages. To obtain accurate metamorphic, deformation, and closure temperatures of thermochronological systems, pressures and cooling rates for the period of interest were derived by inverse modeling of multiple thermochronological data sets, and temperatures were determined by iterative calculations. The Raman spectroscopy of carbonaceous material results indicate two temperature sequences separated by a thrust. In the external sequence, peak temperatures are constant across the structural strike, consistent with the observed hinterland-dipping duplex system. In the internal temperature sequence associated with the MCT shear zone, each geothermometer yields an apparent inverted temperature gradient although with different temperature ranges, and all temperatures appear to be retrograde. These observations are consistent with the quartz microfabrics. Further, all thermochronometers indicate upward younging across the MCT. We interpret our data as a composite peak and deformation temperature sequence that formed successively and reflects the broadening and narrowing of the MCT shear zone in which the ductile deformation lasted until similar to 11 Ma.
- Published
- 2020
25. THE TIMING AND TEMPO OF QUATERNARY RHYOLITE DOME CONSTRUCTION AT THE COSO VOLCANIC FIELD
- Author
-
Jorge A. Vazquez, Seth D. Burgess, and Matthew A. Coble
- Subjects
geography ,Dome (geology) ,geography.geographical_feature_category ,Volcano ,Field (physics) ,Rhyolite ,Geochemistry ,Quaternary ,Geology - Published
- 2020
26. Hadean zircon from a 3.3 Ga sandstone, Barberton greenstone belt, South Africa
- Author
-
Nadja Drabon, Gary R. Byerly, Benjamin L. Byerly, Dale H. Burns, Donald R. Lowe, and Matthew A. Coble
- Subjects
010504 meteorology & atmospheric sciences ,Hadean ,Geochemistry ,Geology ,Greenstone belt ,010502 geochemistry & geophysics ,01 natural sciences ,0105 earth and related environmental sciences ,Zircon - Published
- 2018
27. Trace Element Characterisation of <scp>MAD</scp> ‐559 Zircon Reference Material for Ion Microprobe Analysis
- Author
-
Jorge A. Vazquez, Andrew P. Barth, Joseph L. Wooden, Dale H. Burns, Simon E. Jackson, Cara E. Vennari, Matthew A. Coble, and Andrew R.C. Kylander-Clark
- Subjects
Secondary ion mass spectrometry ,Microprobe ,Materials science ,010504 meteorology & atmospheric sciences ,Geochemistry and Petrology ,Trace element ,Analytical chemistry ,Geology ,010502 geochemistry & geophysics ,01 natural sciences ,0105 earth and related environmental sciences ,Ion ,Zircon - Published
- 2018
28. Early Onset of Franciscan Subduction
- Author
-
Howard W. Day, Jesslyn K. Starnes, Sean R. Mulcahy, Matthew A. Coble, and Jeffrey D. Vervoort
- Subjects
Geophysics ,010504 meteorology & atmospheric sciences ,Subduction ,Geochemistry and Petrology ,Geochemistry ,Eclogite ,010502 geochemistry & geophysics ,01 natural sciences ,Geology ,0105 earth and related environmental sciences ,Early onset - Published
- 2018
29. Generation of Silicic Melts in the Early Izu‐Bonin Arc Recorded by Detrital Zircons in Proximal Arc Volcaniclastic Rocks From the Philippine Sea
- Author
-
Sebastien Meffre, Osamu Ishizuka, Matthew A. Coble, John T. Shukle, Richard J. Arculus, Kenichiro Tani, J. L. Wooden, and A.P. Barth
- Subjects
Provenance ,010504 meteorology & atmospheric sciences ,Subduction ,Trace element ,Geochemistry ,Silicic ,Pyroclastic rock ,010502 geochemistry & geophysics ,01 natural sciences ,Geophysics ,Geochemistry and Petrology ,Geochronology ,Island arc ,Geology ,0105 earth and related environmental sciences ,Zircon - Abstract
A 1.2 km thick Paleogene volcaniclastic section at International Ocean Discovery Program Site 351-U1438 preserves the deep-marine, proximal record of Izu-Bonin oceanic arc initiation, and volcano evolution along the Kyushu-Palau Ridge (KPR). Pb/U ages and trace element compositions of zircons recovered from volcaniclastic sandstones preserve a remarkable temporal record of juvenile island arc evolution. Pb/U ages ranging from 43 to 27 Ma are compatible with provenance in one or more active arc edifices of the northern KPR. The abundances of selected trace elements with high concentrations provide insight into the genesis of U1438 detrital zircon host melts, and represent useful indicators of both short and long-term variations in melt compositions in arc settings. The Site U1438 zircons span the compositional range between zircons from mid-ocean ridge gabbros and zircons from relatively enriched continental arcs, as predicted for melts in a primitive oceanic arc setting derived from a highly depleted mantle source. Melt zircon saturation temperatures and Ti-in-zircon thermometry suggest a provenance in relatively cool and silicic melts that evolved toward more Th and U-rich compositions with time. Th, U, and light rare earth element enrichments beginning about 35 Ma are consistent with detrital zircons recording development of regional arc asymmetry and selective trace element-enriched rear arc silicic melts as the juvenile Izu-Bonin arc evolved.
- Published
- 2017
30. Zircon geochronology and geochemistry of Quaternary rhyolite domes of the Coso volcanic field, Inyo County, California
- Author
-
Matthew A. Coble, Seth D. Burgess, and Jorge A. Vazquez
- Subjects
Volcanic hazards ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Geochemistry ,Silicic ,010502 geochemistry & geophysics ,01 natural sciences ,Geophysics ,Volcano ,Geochemistry and Petrology ,Geochronology ,Magma ,Rhyolite ,Magmatism ,Geology ,0105 earth and related environmental sciences ,Zircon - Abstract
The Quaternary Coso volcanic field (CVF) is a compositionally bimodal volcanic field located within a releasing bend along the eastern range-front Sierra Nevada fault zone in California's southern Owens Valley. The erupted products of CVF silicic magmatism since ~1 Ma comprise 38 high-silica rhyolite domes, with the volumetric majority (~99%) of rhyolite emplaced within the past ~300 ka. The CVF hosts an economically important geothermal field driven by heat associated with a shallow (~5 km) igneous intrusion. The CVF is potentially an immature analog to the nearby Long Valley system, which culminated in generation and eruption of the voluminous and widespread Bishop Tuff. As such, the CVF represents a considerable volcanic hazard, making a detailed understanding of the eruptive history and pre-eruptive conditions of the system critically important. We present uranium-series isochron dates from zircon ± allanite crystal surfaces and zircon trace element geochemical data on the youngest 17 rhyolite domes at Coso, which represent ~60% (by volume) of the silicic magma erupted by the system. These data suggest: (1) a shorter emplacement duration than previously recognized for these domes, with a duration of 20 ± 5 ka; (2) 4 shorter-duration eruption pulses within this interval, all of which occur during the marine isotope stage (MIS) 5 interglacial period; (3) an uptick in the volume of CVF magma erupted between ~200 ka and ~ 78 ka relative to that emplaced over the lifetime of the system; (4) near-coeval eruption of geochemically distinct magma in close geographic proximity, either sourced from different portions of the same magma system at depth or from discrete, uncommunicating bodies; (5) ambiguity with respect to whether or not CVF magmatism is time-predictable, as previously suggested, or erupted as a series of punctuated episodes; (6) no rhyolite volcanism in the past ~78 kyr.
- Published
- 2021
31. Alkaline granitic magmatism of the Western Transbaikalia: Petrogenetic and geodynamic implications from U-Pb isotopic–geochronological data
- Author
-
O. V. Udoratina, Matthew A. Coble, G. N. Burmakina, A.A. Tsygankov, and V. B. Khubanov
- Subjects
geography ,Plateau ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Pluton ,Geochemistry ,Geology ,010502 geochemistry & geophysics ,01 natural sciences ,Peralkaline rock ,Geochemistry and Petrology ,Magmatism ,Alkali feldspar ,0105 earth and related environmental sciences - Abstract
The Mongolian–Transbaikalian volcanoplutonic belt extends for almost 2000 km through northern Mongolia and Transbaikalia and hosts several hundreds of plutons of alkali feldspar syenites (AFS) and peralkaline granites (PA) that formed at 280–270 and 230–210 Ma. The giant (~220 km2 in area) Sherbakhta pluton in the Vitim plateau (western Transbaikalia) is located and composed of metaluminous (A/CNK ≤1), high ferroan AFS syenites (10.7–12.3 wt% Na2O + K2O; NK/A
- Published
- 2021
32. A microanalytical oxygen isotopic and U-Th geochronologic investigation and modeling of rhyolite petrogenesis at the Krafla Central Volcano, Iceland
- Author
-
Richard A. Stern, R.L. Hampton, Ilya N. Bindeman, Shane M. Rooyakkers, and Matthew A. Coble
- Subjects
Basalt ,Fractional crystallization (geology) ,010504 meteorology & atmospheric sciences ,Continental crust ,Geochemistry ,Silicic ,Magma chamber ,010502 geochemistry & geophysics ,01 natural sciences ,Geophysics ,Geochemistry and Petrology ,Magma ,Caldera ,Mafic ,Geology ,0105 earth and related environmental sciences - Abstract
Understanding the petrogenesis of silicic magmas is critical for understanding the volcanic hazards they pose, their geothermal energy potential, and the creation of continental crust. In this study we explore the origin of rhyolitic magmas in basaltic crust at the Krafla Central Volcano in Iceland. We present laser fluorination oxygen isotope analyses of plagioclase, pyroxene, and groundmass from eight rhyolites and six selected basalts, as well as in situ oxygen isotope analyses and U-Th geochronology of zircons from three rhyolitic domes erupted around the caldera margins. Zircon U-Th geochronology for the rhyolite domes yields ages of 88.7 ± 9.9 ka for Jorundur, 83.3 ± 9.2 ka for Hliðarfjall, and 85.5 ± 9.4 ka for Gaesafjallarani, some 20–30 ka after the eruption of the zoned rhyolite to basalt Halarauður ignimbrite during a major collapse of the Krafla caldera. We suggest that the domes represent a renewed episode of silicic magma production in the pre-heated crust. Oxygen isotope analyses of single and bulk plagioclase and pyroxene identify some instances of isotopic disequilibrium with groundmass (~3.5‰) reflecting assimilation of diverse low δ18O crustal material. However, zircon is largely in equilibrium with groundmass analyses, suggesting it crystallized directly from low δ18O magma. Zircon trace elements (Hf, Yb, Th, U) for all three domes show trends indicative of fractional crystallization. Pairing these observations with two-dimensional thermal modeling using the Heat2D model, and chemical modeling using the Magma Chamber Simulator, we suggest that petrogenesis of rhyolitic magma at Krafla requires at least two-steps: the δ18O of basaltic parental magmas are first lowered through assimilation of hydrothermally altered material (generated in the high temperature region in the crust surrounding the magma chamber) to produce low δ18O mafic to intermediate magmas, which then ascend from magma generation zones into colder crust where they undergo further fractional crystallization at shallower depths. Our models suggest that prior hydrothermal alteration of the mafic crust greatly increases the volume of partial melt that can be produced and assimilated, and we thus suggest that long-lived hydrothermal systems may play an important role in further encouraging the production of larger volumes of rhyolitic magmas in basalt-dominated environments.
- Published
- 2021
33. New zircon (U-Th)/He and U/Pb eruption age for the Rockland tephra, western USA
- Author
-
Seth D. Burgess, Erik W. Klemetti, and Matthew A. Coble
- Subjects
Archeology ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Geochemistry ,Geology ,010502 geochemistry & geophysics ,01 natural sciences ,Volcano ,Geochronology ,Magma ,Tephra ,Lava Creek Tuff ,Tephrochronology ,Quaternary ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Zircon - Abstract
Eruption ages of a number of prominent Quaternary volcanic deposits remain inaccurately and/or imprecisely constrained, despite their importance as regional stratigraphic markers in paleo-environment reconstruction and as evidence of climate-altering eruptions. Accurately dating volcanic deposits presents challenging analytical considerations, including poor radiogenic yield, scarcity of datable minerals, and contamination of crystal populations by magma, eruption, and transport processes. One prominent example is the Rockland tephra, which erupted from the Lassen Volcanic Center in the southern Cascade arc. Despite a range in published eruption ages from 0.40 to 0.63 Ma, the Rockland tephra is extensively used as a marker bed across the western United States. To more accurately and precisely constrain the age of the Rockland tephra-producing eruption, we report U/Pb crystallization dates from the outermost ∼2 μm of zircon crystal faces (surfaces) using secondary ion mass spectrometry (SIMS). Our new weighted mean 238 U/ 206 Pb age for Rockland tephra zircon surfaces is 0.598 ± 0.013 Ma (2σ) and MSWD = 1.11 (mean square weighted deviation). As an independent test of the accuracy of this age, we obtained new (U-Th)/He dates from individual zircon grains from the Rockland tephra, which yielded a weighted mean age of 0.599 ± 0.012 Ma (2σ, MSWD = 5.13). We also obtained a (U-Th)/He age of 0.628 ± 0.014 Ma (MSWD = 1.19) for the Lava Creek Tuff member B, which was analyzed as a secondary standard to test the accuracy of the (U-Th)/He technique for Quaternary tephras, and to evaluate assumptions made in the model-age calculation. Concordance of new U/Pb and (U-Th)/He zircon ages reinforces the accuracy of our preferred Rockland tephra eruption age, and confirms that zircon surface dates sample zircon growth up to the time of eruption. We demonstrate the broad applicability of coupled U/Pb zircon-surface and single-grain zircon (U-Th)/He geochronology to accurate dating of Quaternary tephra, and highlight the challenges and opportunities of this technique.
- Published
- 2017
34. Lithium enrichment in intracontinental rhyolite magmas leads to Li deposits in caldera basins
- Author
-
Matthew A. Coble, Gail A. Mahood, James J. Rytuba, and Thomas R. Benson
- Subjects
Multidisciplinary ,Felsic ,010504 meteorology & atmospheric sciences ,Continental crust ,Science ,Geochemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Weathering ,General Chemistry ,010502 geochemistry & geophysics ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Hydrothermal circulation ,Article ,chemistry ,Rhyolite ,Caldera ,Lithium ,Geology ,0105 earth and related environmental sciences ,Melt inclusions - Abstract
The omnipresence of lithium-ion batteries in mobile electronics, and hybrid and electric vehicles necessitates discovery of new lithium resources to meet rising demand and to diversify the global lithium supply chain. Here we demonstrate that lake sediments preserved within intracontinental rhyolitic calderas formed on eruption and weathering of lithium-enriched magmas have the potential to host large lithium clay deposits. We compare lithium concentrations of magmas formed in a variety of tectonic settings using in situ trace-element measurements of quartz-hosted melt inclusions to demonstrate that moderate to extreme lithium enrichment occurs in magmas that incorporate felsic continental crust. Cenozoic calderas in western North America and in other intracontinental settings that generated such magmas are promising new targets for lithium exploration because lithium leached from the eruptive products by meteoric and hydrothermal fluids becomes concentrated in clays within caldera lake sediments to potentially economically extractable levels., Lithium is increasingly being utilized for modern technology in the form of lithium-ion batteries. Here, using in situ measurements of quartz-hosted melt inclusions, the authors demonstrate that preserved lake sediments within rhyolitic calderas have the potential to host large lithium-rich clay deposits.
- Published
- 2017
35. Early Carboniferous anorogenic magmatism in the Levant: implications for rifting in northern Gondwana
- Author
-
Tzahi Golan, Matthew A. Coble, and Yaron Katzir
- Subjects
Underplating ,Rift ,010504 meteorology & atmospheric sciences ,Geology ,Crust ,010502 geochemistry & geophysics ,01 natural sciences ,Gondwana ,Paleontology ,Laurasia ,Oceanic crust ,Carboniferous ,Seismology ,0105 earth and related environmental sciences ,Terrane - Abstract
The Variscan orogenesis in Europe peaked during the Late Devonian–Early Carboniferous times when Gondwanan terranes collided with Laurasia. Hitherto it has been thought that Carboniferous tectonics in northern Arabia and the adjacent parts of NE Africa were broad swells (‘arches’) and depressions (‘basins’) that formed as a far-field contractional effect of the Variscan compression. The discovery of a 351 ± 3 Ma (U–Pb in zircon) within-plate felsic volcanism in the Helez borehole, southern coastal Israel, suggests that the Levant Arch is, instead, extensional in origin. Felsic volcanism was associated with gabbro underplating of the crust, an extreme (~50°C/km) crustal thermal gradient, major uplift, and truncation of the ≥2.5 km section. Taken together with the recent discovery of the ~340 Ma oceanic crust in the Eastern Mediterranean, the Levant Arch is interpreted as an uplifted shoulder of a rift, preceding ocean spreading.
- Published
- 2017
36. Dating the Paleoproterozoic snowball Earth glaciations using contemporaneous subglacial hydrothermal systems
- Author
-
D. O. Zakharov, Ilya N. Bindeman, A.I. Slabunov, Maria Ovtcharova, Matthew A. Coble, N.S. Serebryakov, and Urs Schaltegger
- Subjects
Zircon ,010504 meteorology & atmospheric sciences ,Gabbro ,Great Oxygenation Event ,Snowball Earth ,Geology ,U-Pb ,Paleoproterozoic ,010502 geochemistry & geophysics ,01 natural sciences ,Paleontology ,ddc:550 ,Baltic Shield ,Glacial period ,Great Oxidation Event ,Mafic ,Meltwater ,0105 earth and related environmental sciences - Abstract
The presence of Paleoproterozoic glacial diamictites deposited at low latitudes on different continents indicates that three or four worldwide glaciations occurred between 2.45 and 2.22 Ga. During that time period, the first atmospheric oxygen rise, known as the Great Oxidation Event (GOE), occurred, implying a potential connection between these events. Herein we combine triple oxygen isotope systematics and in situ and high-precision U-Pb zircon ages of mafic intrusions to date two episodes of snowball Earth glaciations. Subglacial hydrothermal alteration was induced by intrusions of high- Mg and high-Fe gabbros during the early Paleoproterozoic rifting on the Baltic Shield, which at the time was located at low latitudes. The low d18O values of hydrothermally altered rocks associated with these intrusions are attributed to high-temperature isotopic exchange between hot rock and glacial meltwater, indicating the presence of glacial ice globally. The triple oxygen isotope approach is used here to show that the d18O of glacial meltwaters during the dated episodes of snowball Earth glaciation was approximately –40 permil VSMOW (Vienna standard mean ocean water). High-Mg gabbro intrusions and associated low-d18O hydrothermally altered rocks formed during the earliest episode of snowball Earth glaciation between 2.43 and 2.41 Ga. High-Fe gabbro from the Khitoostrov locality (Karelia, Russia) hosts a d18O value of −27.3 permil and is dated here at 2291 ± 8 Ma. This age is interpreted to reflect the interaction between the intrusion and glacial meltwaters during the third Paleoproterozoic glaciation, which occurred after the GOE.
- Published
- 2017
37. The tempo of continental arc construction in the Mesozoic Median Batholith, Fiordland, New Zealand
- Author
-
Joseph F. Sadorski, Harold H. Stowell, Andy J. Tulloch, Keith A. Klepeis, Joshua J. Schwartz, and Matthew A. Coble
- Subjects
010504 meteorology & atmospheric sciences ,Earth science ,Pluton ,Geochemistry ,Geology ,Crust ,010502 geochemistry & geophysics ,01 natural sciences ,Plutonism ,Continental arc ,Batholith ,Magmatism ,Mafic ,0105 earth and related environmental sciences ,Zircon - Abstract
We investigate the temporal record of magmatism in the Fiordland sector of the Median Batholith (New Zealand) with the goal of evaluating models for cyclic and episodic patterns of magmatism and deformation in continental arcs. We compare 20 U-Pb zircon ages from >2300 km2 of Mesozoic lower and middle crust of the Western Fiordland Orthogneiss to existing data from the Median Batholith to: (1) document the tempo of arc construction, (2) estimate rates of magmatic addition at various depths during arc construction, and (3) evaluate the role of cyclical feedbacks between magmatism and deformation during high and low magma addition rate events. Results from the Western Fiordland Orthogneiss indicate that the oldest dates are distributed in northern and southern extremities: the Worsley Pluton (123–121 Ma), eastern McKerr Intrusives (128–120 Ma), and Breaksea Orthogneiss (123 Ma). Dates within the interior of the Western Fiordland Orthogneiss (Misty and Malaspina Plutons, western McKerr Intrusives) primarily range from 118 to 115 Ma and signify a major flux of mafic to intermediate magmatism during which nearly 70% of the arc root was emplaced during a brief, ∼3 m.y., interval. The spatial distribution of dates reveals an inward-focusing, arc-parallel younging of magmatism within the Western Fiordland Orthogneiss during peak magmatic activity. Coupled with existing data from the wider Median Batholith, our data show that Mesozoic construction of the Median Batholith involved at least two high-flux magmatic events: a surge of low-Sr/Y plutonism in the Darran Suite from ca. 147 to 136 Ma, and a terminal surge of high-Sr/Y magmatism in the Separation Point Suite from 128 to 114 Ma, shortly before extensional collapse of the Zealandia Cordillera at 108–106 Ma. Separation Point Suite magmatism occurred at all structural levels, but was concentrated in the lower crust, where nearly 50% of the crust consists of Cretaceous arc-related plutonic rocks. Existing isotopic data suggest that the flare-up of high-Sr/Y magmatism was primarily sourced from the underlying mantle, indicating an externally triggered, dynamic mantle process for triggering the Zealandia high–magma addition rate event, with only limited contributions from upper plate materials.
- Published
- 2017
38. Chemical abrasion-SIMS (CA-SIMS) U-Pb dating of zircon from the late Eocene Caetano caldera, Nevada
- Author
-
Jorge A. Vazquez, David A. John, Christopher D. Henry, Joseph P. Colgan, Matthew A. Coble, and Kathryn E. Watts
- Subjects
Radiogenic nuclide ,Sensitive high-resolution ion microprobe ,010504 meteorology & atmospheric sciences ,Geochemistry ,Trace element ,Mineralogy ,Geology ,Thermal ionization mass spectrometry ,010502 geochemistry & geophysics ,Sanidine ,01 natural sciences ,Metamictization ,Geochemistry and Petrology ,Geochronology ,0105 earth and related environmental sciences ,Zircon - Abstract
Zircon geochronology is a critical tool for establishing geologic ages and time scales of processes in the Earth's crust. However, for zircons compromised by open system behavior, achieving robust dates can be difficult. Chemical abrasion (CA) is a routine step prior to thermal ionization mass spectrometry (TIMS) dating of zircon to remove radiation-damaged parts of grains that may have experienced open system behavior and loss of radiogenic Pb. While this technique has been shown to improve the accuracy and precision of TIMS dating, its application to high-spatial resolution dating methods, such as secondary ion mass spectrometry (SIMS), is relatively uncommon. In our efforts to U-Pb date zircons from the late Eocene Caetano caldera by SIMS (SHRIMP-RG: sensitive high resolution ion microprobe, reverse geometry), some grains yielded anomalously young U-Pb ages that implicated Pb-loss and motivated us to investigate with a comparative CA and non-CA dating study. We present CA and non-CA 206 Pb/ 238 U ages and trace elements determined by SHRIMP-RG for zircons from three Caetano samples (Caetano Tuff, Redrock Canyon porphyry, and a silicic ring-fracture intrusion) and for R33 and TEMORA-2 reference zircons. We find that non-CA Caetano zircons have weighted mean or bimodal U-Pb ages that are 2–4% younger than CA zircons for the same samples. CA Caetano zircons have mean U-Pb ages that are 0.4–0.6 Myr older than the 40 Ar/ 39 Ar sanidine eruption age (34.00 ± 0.03 Ma; error-weighted mean, 2σ), whereas non-CA zircons have ages that are 0.7–1.3 Myr younger. U-Pb ages do not correlate with U (~ 100–800 ppm), Th (~ 50–300 ppm) or any other measured zircon trace elements (Y, Hf, REE), and CA and non-CA Caetano zircons define identical trace element ranges. No statistically significant difference in U-Pb age is observed for CA versus non-CA R33 or TEMORA-2 zircons. Optical profiler measurements of ion microprobe pits demonstrate consistent depths of ~ 1.6 μm for CA and non-CA Caetano, R33 and TEMORA-2 zircons, and do not indicate variations in secondary ion sputtering rates due to chemical or structural changes from the CA treatment. Our new data underscore the potential for cryptic Pb-loss to go unrecognized in other geologically young magmatic centers that do not have zircons with high U, statistically discordant isotope ratios, high common Pb, or metamict textures.
- Published
- 2016
39. Age, geochemistry, and significance of Devonian felsic magmatism in the North Slope subterrane, Yukon, Canadian Arctic
- Author
-
Justin V. Strauss, Werner von Gosen, Benjamin G. Johnson, Karsten Piepjohn, William C. McClelland, Peter W. Crockford, William P. Ward, Maurice Colpron, Joshua Landis, and Matthew A. Coble
- Subjects
Felsic ,Arctic ,Magmatism ,Geochemistry ,Devonian ,Geology - Published
- 2019
40. The timing of migmatization in the northern Arabian–Nubian Shield: Evidence for a juvenile sedimentary component in collision‐related batholiths
- Author
-
Bar Elisha, Tzahi Golan, Yaron Katzir, Matthew A. Coble, and Andrew R.C. Kylander-Clark
- Subjects
Geochemistry and Petrology ,Batholith ,Shield ,Component (UML) ,Geochemistry ,Juvenile ,Geology ,Sedimentary rock ,Collision ,Migmatite - Published
- 2019
41. U-PB EVIDENCE FOR MIDDLE DEVONIAN METAMORPHISM OF THE PETERSEN BAY ASSEMBLAGE ADJACENT TO THE PEARYA TERRANE, ELLESMERE ISLAND
- Author
-
Jane A. Gilotti, Karolina Kosminska, William C. McClelland, and Matthew A. Coble
- Subjects
Geochemistry ,Assemblage (archaeology) ,Metamorphism ,Bay ,Devonian ,Geology ,Terrane - Published
- 2019
42. U-PB TITANITE DATES CORROBORATE VERY SLOW EXHUMATION OF THE NORTH-EAST GREENLAND ULTRAHIGH-PRESSURE TERRANE FROM THE CALEDONIAN OROGEN
- Author
-
Bill McClelland, Matthew A. Coble, and Jane A. Gilotti
- Subjects
Titanite ,Geochemistry ,engineering ,North east ,engineering.material ,Geology ,Terrane - Published
- 2019
43. GHR1 Zircon - A New Eocene Natural Reference Material for Microbeam U-Pb Geochronology and Hf Isotopic Analysis of Zircon
- Author
-
Joel W. DesOrmeau, Seth D. Burgess, Matthew A. Coble, George E. Gehrels, Michael P. Eddy, Mauricio Ibanez-Mejia, Xian-Hua Li, Mark Pecha, Kei Sato, Tiantian Wang, Victor A. Valencia, Blair Schoene, Jeffrey D. Vervoort, Umberto G. Cordani, and Scott A. Maclennan
- Subjects
010504 meteorology & atmospheric sciences ,ZIRCÃO ,Mc icp ms ,Radiochemistry ,Geology ,Microbeam ,010502 geochemistry & geophysics ,01 natural sciences ,Secondary ion mass spectrometry ,Geochemistry and Petrology ,La icp ms ,Geochronology ,0105 earth and related environmental sciences ,Isotope analysis ,Zircon - Published
- 2019
44. MAPPING THE FORMATION OF THE LOWER OCEANIC CRUST IN FOUR DIMENSIONS: HIGH-PRECISION U-PB DATING FROM IODP HOLE U1473A, ATLANTIS BANK, SOUTHWEST INDIAN RIDGE
- Author
-
James L. Crowley, Barbara E John, Matthew A. Coble, Michael J Cheadle, C. J. Doorn, Matthew Rioux, and Mark D. Schmitz
- Subjects
Paleontology ,Oceanic crust ,Ridge (meteorology) ,Geology - Published
- 2019
45. U-Pb zircon geochronology of calc-alkaline ash-flow tuff units in the Mogollon-Datil volcanic field, southern New Mexico
- Author
-
Gary S. Michelfelder, Shannon P. Rentz, Emily E. Salings, and Matthew A. Coble
- Subjects
geography ,geography.geographical_feature_category ,Flow (mathematics) ,Field (physics) ,Volcano ,Geochronology ,Geochemistry ,Geology ,Zircon - Published
- 2019
46. POSSIBLE EVIDENCE FOR LARGE DEPARTURES FROM LITHOSTATIC PRESSURE DURING CRETACEOUS METAMORPHISM IN THE NORTHERN SNAKE RANGE METAMORPHIC CORE COMPLEX (MCC), NEVADA
- Author
-
Matthew A. Coble, Marty Grove, Elizabeth L. Miller, Carl W. Hoiland, and Jeremy K. Hourigan
- Subjects
Metamorphic core complex ,Range (biology) ,Metamorphism ,Overburden pressure ,Petrology ,Geology ,Cretaceous - Published
- 2019
47. TIMING OF OBLIQUE MOTION OF THE LA PUNTILLA – LA FALDA SHEAR ZONE IN NORTHWEST ARGENTINA FROM MONAZITE U-PB GEOCHRONOLOGY
- Author
-
Sean R. Mulcahy, Alexandra Nordin, Emily Houlihan, Andrew Tholt, Sarah M. Roeske, Vinicius T. Meira, Patricia Webber, Wes Johns, Matthew A. Coble, and William C. McClelland
- Subjects
Monazite ,Geochronology ,Oblique case ,Shear zone ,Geomorphology ,Geology - Published
- 2019
48. ZIRCON GEOCHEMISTRY AND PB-U (SHRIMP-RG) AGES OF THE CORNUCOPIA STOCK, NORTHEASTERN OREGON, AND A RE-EXAMINATION OF MAGMA SOURCES
- Author
-
Matthew A. Coble, Kenneth Johnson, and Mark A. Bradley
- Subjects
Geochemistry ,Geology ,Stock (geology) ,Shrimp ,Zircon - Published
- 2019
49. TIMING AND KINEMATICS OF INTRA-ARC DEFORMATION IN THE MIDDLE CRUST OF THE FAMATINA ARC
- Author
-
Patricia Webber, Wes Johns, Matthew A. Coble, Sarah M. Roeske, Emily Houlihan, Andrew Tholt, Sean R. Mulcahy, William C. McClelland, and Jeffrey D. Vervoort
- Subjects
Arc (geometry) ,Crust ,Kinematics ,Deformation (meteorology) ,Geology ,Seismology - Published
- 2019
50. Multistage growth and compositional change at the Goat Rocks volcanic complex, a major Pliocene–Pleistocene andesite center in the southern Washington Cascades
- Author
-
Kellie T. Wall, Anita L. Grunder, Daniel P. Miggins, and Matthew A. Coble
- Subjects
geography ,geography.geographical_feature_category ,Volcano ,Pleistocene ,Andesite ,Geochemistry ,Center (algebra and category theory) ,Geology - Published
- 2019
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