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• 1. [Article] Timescales of large silicic magma systems : implications from accessory minerals in Pleistocene lavas of the Altiplano-Puna Volcanic Complex, central Andes

  Constraining the development, evolution, and timescales of large silicic magma systems is important to understanding the development of granite batholiths, the relationships between volcanoes and their ...

  Citation × Citation Citation Abstract Copy Title: Timescales of large silicic magma systems : implications from accessory minerals in Pleistocene lavas of the Altiplano-Puna Volcanic Complex, central Andes Author: Tierney, Casey R. Constraining the development, evolution, and timescales of large silicic magma systems is important to understanding the development of granite batholiths, the relationships between volcanoes and their plutonic underpinnings, and the development of the continental crust. The ignimbrite flare up that produced the Altiplano-Puna Volcanic Complex of the Central Andes is characterized by episodic volcanism over a ~11 Ma time-span that climaxed about 4 Ma. Since peak activity, the temporal and spatial record of volcanism suggests a waning of the system with only one other supervolcanic eruption at 2.6 Ma. The most recent phase of volcanism from the APVC comprises a series of late Pleistocene domes that share a general petrochemical resemblance to the ignimbrites. New U-Th/U-Pb data on zircons and high precision 40Ar/39Ar age determinations reveal that these effusive eruptions represent a temporally coherent magmatic episode. The five largest domes (Chao, Chillahuita, Chanka, Chascon-Runtu Jarita, and Tocopuri) have a combined volume >40 km³, and are distributed over a roughly elliptical area of almost 2000km² centered at 22°S 68°W. They are crystal rich (>50%) dacites to rhyolites. ⁴⁰Ar/³⁹Ar ages from biotite reveals eruption ages from 108±6 to 120±5 ka while more accurate sanidine for some of the domes reveal eruption ages from 87±4 to 97±2 ka. SIMS U-series crystallization ages from the rims of 215 zircon crystals from the domes show a similar age spectra from dome to dome, with common peaks in zircon ages at ~100ka and ~220ka. Furthermore, the ages reveal a fairly continuous spread of ages from near eruption to >300ka indicating that the residence time of this magma body was likely over a similar time interval. Ubiquitous andesitic inclusions evidence a vital role for recharge in sustaining and maybe eventual eruption of these magmas. Lastly, the interiors of crystals with rim U-Th secular equilibrium ages were re-analyzed and have yielded U-Pb ages of up to 3.5 Ma. The presence of these older interiors suggests that the source region of these magmas retained a record of an earlier history dating back to the last supervolcanic eruption in the region from the nearby Pastos Grandes caldera. This suggests that the thermal history of the system precluded complete resorption of antecrysts. The volcanological, petrological, temporal and spatial coherence of this series of eruptions combined with the similar ⁴⁰Ar/³⁹Ar and zircon age spectra argue for a long-lived and unitary magma chamber revealing perhaps the waning of this major continental magma system. Title: Timescales of large silicic magma systems : implications from accessory minerals in Pleistocene lavas of the Altiplano-Puna Volcanic Complex, central Andes Author: Tierney, Casey R. Constraining the development, evolution, and timescales of large silicic magma systems is important to understanding the development of granite batholiths, the relationships between volcanoes and their plutonic underpinnings, and the development of the continental crust. The ignimbrite flare up that produced the Altiplano-Puna Volcanic Complex of the Central Andes is characterized by episodic volcanism over a ~11 Ma time-span that climaxed about 4 Ma. Since peak activity, the temporal and spatial record of volcanism suggests a waning of the system with only one other supervolcanic eruption at 2.6 Ma. The most recent phase of volcanism from the APVC comprises a series of late Pleistocene domes that share a general petrochemical resemblance to the ignimbrites. New U-Th/U-Pb data on zircons and high precision 40Ar/39Ar age determinations reveal that these effusive eruptions represent a temporally coherent magmatic episode. The five largest domes (Chao, Chillahuita, Chanka, Chascon-Runtu Jarita, and Tocopuri) have a combined volume >40 km³, and are distributed over a roughly elliptical area of almost 2000km² centered at 22°S 68°W. They are crystal rich (>50%) dacites to rhyolites. ⁴⁰Ar/³⁹Ar ages from biotite reveals eruption ages from 108±6 to 120±5 ka while more accurate sanidine for some of the domes reveal eruption ages from 87±4 to 97±2 ka. SIMS U-series crystallization ages from the rims of 215 zircon crystals from the domes show a similar age spectra from dome to dome, with common peaks in zircon ages at ~100ka and ~220ka. Furthermore, the ages reveal a fairly continuous spread of ages from near eruption to >300ka indicating that the residence time of this magma body was likely over a similar time interval. Ubiquitous andesitic inclusions evidence a vital role for recharge in sustaining and maybe eventual eruption of these magmas. Lastly, the interiors of crystals with rim U-Th secular equilibrium ages were re-analyzed and have yielded U-Pb ages of up to 3.5 Ma. The presence of these older interiors suggests that the source region of these magmas retained a record of an earlier history dating back to the last supervolcanic eruption in the region from the nearby Pastos Grandes caldera. This suggests that the thermal history of the system precluded complete resorption of antecrysts. The volcanological, petrological, temporal and spatial coherence of this series of eruptions combined with the similar ⁴⁰Ar/³⁹Ar and zircon age spectra argue for a long-lived and unitary magma chamber revealing perhaps the waning of this major continental magma system. Close

• 2. [Article] Age of the Batoka basalts, norther Zimbabwe, and the duration of Karoo Large Igneous Province magmatism

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Age of the Batoka basalts, norther Zimbabwe, and the duration of Karoo Large Igneous Province magmatism Author: Briden, J. C., Jones, D. L., MacNiocaill, C., Duncan, Robert A., Randall, D. E. copyrighted by American Geophysical Union Title: Age of the Batoka basalts, norther Zimbabwe, and the duration of Karoo Large Igneous Province magmatism Author: Briden, J. C., Jones, D. L., MacNiocaill, C., Duncan, Robert A., Randall, D. E. copyrighted by American Geophysical Union Close

• 3. [Article] Ar-Ar Age Correlation of the Elkhorn Mountain Volcanics and Base Metal Mineralization in the Ratio Mountain Quadrangle, Montana

  Citation × Citation Citation Abstract Copy Title: Ar-Ar Age Correlation of the Elkhorn Mountain Volcanics and Base Metal Mineralization in the Ratio Mountain Quadrangle, Montana Author: Horton, Thomas Title: Ar-Ar Age Correlation of the Elkhorn Mountain Volcanics and Base Metal Mineralization in the Ratio Mountain Quadrangle, Montana Author: Horton, Thomas Close

• 4. [Article] Geochronology and paleoclimatic implications of the last deglaciation 2 of the Mauna Kea Ice Cap, Hawaii

  NEWS COVERAGE: A news release based on this journal publication, which is written for a lay audience and has been approved by an author of the study, is available online: http://bit.ly/972JOT

  Citation × Citation Citation Abstract Copy Title: Geochronology and paleoclimatic implications of the last deglaciation 2 of the Mauna Kea Ice Cap, Hawaii Author: Durz, Mark D., Clark, Peter U., 1956-, Hostetler, Steven W., Anslow, Faron S. NEWS COVERAGE: A news release based on this journal publication, which is written for a lay audience and has been approved by an author of the study, is available online: http://bit.ly/972JOT Title: Geochronology and paleoclimatic implications of the last deglaciation 2 of the Mauna Kea Ice Cap, Hawaii Author: Durz, Mark D., Clark, Peter U., 1956-, Hostetler, Steven W., Anslow, Faron S. NEWS COVERAGE: A news release based on this journal publication, which is written for a lay audience and has been approved by an author of the study, is available online: http://bit.ly/972JOT Close

• 5. [Article] Prolonged plume volcanism in the Caribbean Large Igneous Province: New insights from Curaçao and Haiti

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/.

  Citation × Citation Citation Abstract Copy Title: Prolonged plume volcanism in the Caribbean Large Igneous Province: New insights from Curaçao and Haiti Author: Krawl, Kyle, Kent, Adam J. R., Duncan, Robert A., Loewen, Matthew W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/. Title: Prolonged plume volcanism in the Caribbean Large Igneous Province: New insights from Curaçao and Haiti Author: Krawl, Kyle, Kent, Adam J. R., Duncan, Robert A., Loewen, Matthew W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/. Close

• 6. [Article] Spatial and temporal distribution of a C-like asthenoshpheric component in the Rano Rahi Seamount Field, East Pacific Rise, 15°-19°S

  copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Spatial and temporal distribution of a C-like asthenoshpheric component in the Rano Rahi Seamount Field, East Pacific Rise, 15°-19°S Author: Sinton, J. M., Mahoney, J. J., Duncan, Robert A., Hall, L. S. copyrighted by American Geophysical Union. Title: Spatial and temporal distribution of a C-like asthenoshpheric component in the Rano Rahi Seamount Field, East Pacific Rise, 15°-19°S Author: Sinton, J. M., Mahoney, J. J., Duncan, Robert A., Hall, L. S. copyrighted by American Geophysical Union. Close

• 7. [Article] Extension and volcanism : tectonic development of the northwestern margin of the Basin and Range Province in southern Oregon

  The northwestern corner of the Basin and Range Province (NWBR) lies in southeast Oregon where extensive Late Miocene, mafic to bimodal basalt-rhyolite volcanism and extensional faults dominate a stark ...

  Citation × Citation Citation Abstract Copy Title: Extension and volcanism : tectonic development of the northwestern margin of the Basin and Range Province in southern Oregon Author: Scarberry, Kaleb C. The northwestern corner of the Basin and Range Province (NWBR) lies in southeast Oregon where extensive Late Miocene, mafic to bimodal basalt-rhyolite volcanism and extensional faults dominate a stark and arid landscape. Near Lake Abert, the Late Miocene volcanic section abuts Early Miocene, dominantly intermediate composition volcanoes at the Coleman Hills and Rabbit Hills. Such exposures are few in the NWBR and shed light on the volcanic and structural development of the region and significantly extend the known distribution of Early Miocene magmatism. New 40Ar-39Ar ages indicate that magmatism occurred at the Coleman Hills between 21.4 and 22.3 Ma and at the Rabbit Hills between 20.2 and 23.4 Ma. Magmatism at the Coleman Hills initiated with an episode of silicic volcanism that was rapidly followed by the intrusion and emplacement of dacite and andesite dikes and lavas. Early Miocene rhyolite of the Coleman Hills exhibits high 87Sr/86Sri relative to most Late Miocene rocks in the region (0.7051 vs. 0.7037) suggesting that crustal melting was important in their genesis. A notable lack of a Nb-trough, characteristic of subduction zone settings, and high 207Pb/204Pb, and 206Pb/204Pb suggests that these rocks were not generated within a volcanic arc setting and instead likely formed in a back-arc region that had been metasomatized by prior subduction. Crystal fractionation readily accounts for the generation of andesite and dacite compositions from basaltic andesite however a gap in the data between ~66 to 70% SiO2, isotopic variability and disequilibrium textures indicate that crustal anatexis, magma mixing and/or crustal assimilation may also be important processes in the evolutionary history of the Coleman Hills. Dike orientations within Early Miocene volcanoes often mimic the trend of faults that cut Late Miocene volcanic strata, suggesting that the faults may have utilized an existing structural fabric. Contact relations suggest as much as 500 m of volcanic paleo-topography existed near Lake Abert prior to deposition of the Middle Miocene Steens flood basalts at ~16 Ma. Late Miocene structural development of the Abert Rim fault is chronologically linked to the formation and northward propagation of the Walker Lane transform fault system in Nevada between 9 and 3 Ma. At Lake Abert, bimodal basalt-rhyolite volcansim from 8.8 to 7.7 Ma occurred within a zone of active NW-striking faulting. Volcanism during this interval was related to the initiation of faulting at Abert Rim fault. On the basis of morphology and geochemical correlation, Juniper Mountain and Venator Buttes are the source of silicic and mafic volcanism, respectively, between 8.8 to 7.7 Ma. Partial restorations demonstrate that the Abert Rim fault south of 42º40’ N latitude had >250 m of stratigraphic separation prior to deposition of the Rattlesnake Tuff at 7 Ma. The topography north of latitude 42º40’ N was gently sloping at 7 Ma, much like the High Lava Plains are today. Thus, faulting along the NNE-striking Abert Rim initiated between 7.7 and 7 Ma and after the formation of NW-striking fault systems. Title: Extension and volcanism : tectonic development of the northwestern margin of the Basin and Range Province in southern Oregon Author: Scarberry, Kaleb C. The northwestern corner of the Basin and Range Province (NWBR) lies in southeast Oregon where extensive Late Miocene, mafic to bimodal basalt-rhyolite volcanism and extensional faults dominate a stark and arid landscape. Near Lake Abert, the Late Miocene volcanic section abuts Early Miocene, dominantly intermediate composition volcanoes at the Coleman Hills and Rabbit Hills. Such exposures are few in the NWBR and shed light on the volcanic and structural development of the region and significantly extend the known distribution of Early Miocene magmatism. New 40Ar-39Ar ages indicate that magmatism occurred at the Coleman Hills between 21.4 and 22.3 Ma and at the Rabbit Hills between 20.2 and 23.4 Ma. Magmatism at the Coleman Hills initiated with an episode of silicic volcanism that was rapidly followed by the intrusion and emplacement of dacite and andesite dikes and lavas. Early Miocene rhyolite of the Coleman Hills exhibits high 87Sr/86Sri relative to most Late Miocene rocks in the region (0.7051 vs. 0.7037) suggesting that crustal melting was important in their genesis. A notable lack of a Nb-trough, characteristic of subduction zone settings, and high 207Pb/204Pb, and 206Pb/204Pb suggests that these rocks were not generated within a volcanic arc setting and instead likely formed in a back-arc region that had been metasomatized by prior subduction. Crystal fractionation readily accounts for the generation of andesite and dacite compositions from basaltic andesite however a gap in the data between ~66 to 70% SiO2, isotopic variability and disequilibrium textures indicate that crustal anatexis, magma mixing and/or crustal assimilation may also be important processes in the evolutionary history of the Coleman Hills. Dike orientations within Early Miocene volcanoes often mimic the trend of faults that cut Late Miocene volcanic strata, suggesting that the faults may have utilized an existing structural fabric. Contact relations suggest as much as 500 m of volcanic paleo-topography existed near Lake Abert prior to deposition of the Middle Miocene Steens flood basalts at ~16 Ma. Late Miocene structural development of the Abert Rim fault is chronologically linked to the formation and northward propagation of the Walker Lane transform fault system in Nevada between 9 and 3 Ma. At Lake Abert, bimodal basalt-rhyolite volcansim from 8.8 to 7.7 Ma occurred within a zone of active NW-striking faulting. Volcanism during this interval was related to the initiation of faulting at Abert Rim fault. On the basis of morphology and geochemical correlation, Juniper Mountain and Venator Buttes are the source of silicic and mafic volcanism, respectively, between 8.8 to 7.7 Ma. Partial restorations demonstrate that the Abert Rim fault south of 42º40’ N latitude had >250 m of stratigraphic separation prior to deposition of the Rattlesnake Tuff at 7 Ma. The topography north of latitude 42º40’ N was gently sloping at 7 Ma, much like the High Lava Plains are today. Thus, faulting along the NNE-striking Abert Rim initiated between 7.7 and 7 Ma and after the formation of NW-striking fault systems. Close

• 8. [Article] Understanding large resurgent calderas and associated magma systems : the Pastos Grandes Caldera Complex, southwest Bolivia

  The Pastos Grandes Caldera Complex (PGCC) in southwest Bolivia has produced two large-volume (≥800 km³ DRE) dacite ignimbrites from a nested caldera source over a period of 5.5 Myr. In addition to the ...

  Citation × Citation Citation Abstract Copy Title: Understanding large resurgent calderas and associated magma systems : the Pastos Grandes Caldera Complex, southwest Bolivia Author: Kaiser, Jason Frederick, 1985- The Pastos Grandes Caldera Complex (PGCC) in southwest Bolivia has produced two large-volume (≥800 km³ DRE) dacite ignimbrites from a nested caldera source over a period of 5.5 Myr. In addition to the large-volume ignimbrites, a small-volume ignimbrite shield and post-climactic lavas define this composite system. Based on detailed field work and analysis of satellite imagery plus biotite ⁴⁰Ar/³⁹Ar dating, we summarize a revised stratigraphy, areal distribution and volume calculations for ignimbrites. From interpretations of stratigraphy and structures along the caldera margins, we propose an asymmetric collapse hinged along the north and western boundaries. Both the early Chuhuilla (5.45 ± 0.02 Ma), and the younger Pastos Grandes (2.89 ± 0.01 Ma) calderas share the hinge and much of the eastern collapse scarp, however the Chuhuilla caldera defines a much larger area (>1700 km²) compared to the Pastos Grandes (870 km²). It is proposed here that pre-existing regional tectonic weaknesses combined with influences of the magma body caused roof failure and caldera collapse. The vast majority of the ignimbrite volume lies within the Chuhuilla and Pastos Grandes calderas (92 and 75% respectively). Considerable intracaldera fill and the lack of preceding plinian deposits suggest that the caldera collapse was early and the eruptive column was not high and was short-lived. The physical properties of the ignimbrites, the limit of their areal distribution to regional topographic lows along with paleomagnetic characteristics support the idea of dense sluggish pyroclastic flows. New volume calculations using multiple methods update previous estimates, with the Chuhuilla now at approximately 1300 km³ and the Pastos Grandes at 800 km³. The ignimbrite volumes and spatial pattern of vents suggest that the caldera complex mirrors the construction of a long-lived composite batholith that focused spatially with time. Eruptions from the PGCC have produced compositionally restricted, high-K dacites with volumetrically minor rhyolites. Combined with granodiorite xenoliths, each caldera cycle contains a progression of textural maturity from ignimbrite, through post-climactic lavas, to remnant pluton. The chemical signatures in the PGCC mirror those of the host Altiplano Puna Volcanic Complex (APVC) and resemble typical arc characteristics (i.e. LIL enriched magmas - Ba/Nb of 4.7-4.8 and Ba/La of 1.6-2.0). However, overprinted on the arc signature are elevated radiogenic isotopes (⁸⁷Sr/⁸⁶Sr ~0.708 - 0.709), which suggest high degrees of crustal assimilation that is thought to be related to increased mantle input from melted asthenosphere. It is suggested here that a combination of assimilation and fractional crystallization from the regional mid-crustal parental source would create the magmas erupted in the PGCC. Subtle decreases in the ⁸⁷Sr/⁸⁶Sr from the Chuhuilla caldera cycle, to the younger Pastos Grandes cycle suggest higher amounts of crustal assimilation related to more heat flow during the peak of the flare up. Zircon chronochemistry reveals that the climactic, caldera-forming eruptions of the PGCC punctuate the protracted magma accumulation and storage periods. The combination of in-situ zircon U-Pb ages with indicators for geochemical evolution (e.g., Zr/Hf, Yb/Gd, Eu/Eu*, Th, U) magmatic temperatures (e.g., Ti) in zircon, reveals protracted magma presence before and after the climactic 2.89 ± 0.01 Ma Pastos Grandes Ignimbrite (PGI) supereruption (~800 km³ of magma) in southwest Bolivia. Zircons from PGI pumice and a lava dome define a pre-climactic magmatic stage of ~0.7 Myr duration prior to the climactic eruption and formation of the eponymous caldera. A further 0.4 Myr of post-climactic zircon crystallization is recorded in lava domes and cogenetic granodiorite clasts. Zircon crystallization is recorded for approximately 1.3 Myr for the Chuhuilla cycle; however the record is entirely pre-climactic. We propose a model for the Pastos Grandes cycle in which the climactic caldera-forming eruption vented the upper portions of the reservoir that were zircon saturated. Subsequently, deeper “remnant” dacite magma previously outside the zone of zircon saturation but crystallizing other major phases, rose to re-establish lithostatic equilibrium, commenced zircon crystallization anew, and drove resurgent volcanism and uplift. This ~1.1 Myr zircon crystallization history records the minimum duration of the lifetime of the PGI supereruption magma from its accumulation to post-climactic solidification. These data support >1 Myr magma lifetimes and a link between volcanic and plutonic realms in large sub-caldera magma reservoirs in the uppermost crust that feed some supereruptions. Title: Understanding large resurgent calderas and associated magma systems : the Pastos Grandes Caldera Complex, southwest Bolivia Author: Kaiser, Jason Frederick, 1985- The Pastos Grandes Caldera Complex (PGCC) in southwest Bolivia has produced two large-volume (≥800 km³ DRE) dacite ignimbrites from a nested caldera source over a period of 5.5 Myr. In addition to the large-volume ignimbrites, a small-volume ignimbrite shield and post-climactic lavas define this composite system. Based on detailed field work and analysis of satellite imagery plus biotite ⁴⁰Ar/³⁹Ar dating, we summarize a revised stratigraphy, areal distribution and volume calculations for ignimbrites. From interpretations of stratigraphy and structures along the caldera margins, we propose an asymmetric collapse hinged along the north and western boundaries. Both the early Chuhuilla (5.45 ± 0.02 Ma), and the younger Pastos Grandes (2.89 ± 0.01 Ma) calderas share the hinge and much of the eastern collapse scarp, however the Chuhuilla caldera defines a much larger area (>1700 km²) compared to the Pastos Grandes (870 km²). It is proposed here that pre-existing regional tectonic weaknesses combined with influences of the magma body caused roof failure and caldera collapse. The vast majority of the ignimbrite volume lies within the Chuhuilla and Pastos Grandes calderas (92 and 75% respectively). Considerable intracaldera fill and the lack of preceding plinian deposits suggest that the caldera collapse was early and the eruptive column was not high and was short-lived. The physical properties of the ignimbrites, the limit of their areal distribution to regional topographic lows along with paleomagnetic characteristics support the idea of dense sluggish pyroclastic flows. New volume calculations using multiple methods update previous estimates, with the Chuhuilla now at approximately 1300 km³ and the Pastos Grandes at 800 km³. The ignimbrite volumes and spatial pattern of vents suggest that the caldera complex mirrors the construction of a long-lived composite batholith that focused spatially with time. Eruptions from the PGCC have produced compositionally restricted, high-K dacites with volumetrically minor rhyolites. Combined with granodiorite xenoliths, each caldera cycle contains a progression of textural maturity from ignimbrite, through post-climactic lavas, to remnant pluton. The chemical signatures in the PGCC mirror those of the host Altiplano Puna Volcanic Complex (APVC) and resemble typical arc characteristics (i.e. LIL enriched magmas - Ba/Nb of 4.7-4.8 and Ba/La of 1.6-2.0). However, overprinted on the arc signature are elevated radiogenic isotopes (⁸⁷Sr/⁸⁶Sr ~0.708 - 0.709), which suggest high degrees of crustal assimilation that is thought to be related to increased mantle input from melted asthenosphere. It is suggested here that a combination of assimilation and fractional crystallization from the regional mid-crustal parental source would create the magmas erupted in the PGCC. Subtle decreases in the ⁸⁷Sr/⁸⁶Sr from the Chuhuilla caldera cycle, to the younger Pastos Grandes cycle suggest higher amounts of crustal assimilation related to more heat flow during the peak of the flare up. Zircon chronochemistry reveals that the climactic, caldera-forming eruptions of the PGCC punctuate the protracted magma accumulation and storage periods. The combination of in-situ zircon U-Pb ages with indicators for geochemical evolution (e.g., Zr/Hf, Yb/Gd, Eu/Eu*, Th, U) magmatic temperatures (e.g., Ti) in zircon, reveals protracted magma presence before and after the climactic 2.89 ± 0.01 Ma Pastos Grandes Ignimbrite (PGI) supereruption (~800 km³ of magma) in southwest Bolivia. Zircons from PGI pumice and a lava dome define a pre-climactic magmatic stage of ~0.7 Myr duration prior to the climactic eruption and formation of the eponymous caldera. A further 0.4 Myr of post-climactic zircon crystallization is recorded in lava domes and cogenetic granodiorite clasts. Zircon crystallization is recorded for approximately 1.3 Myr for the Chuhuilla cycle; however the record is entirely pre-climactic. We propose a model for the Pastos Grandes cycle in which the climactic caldera-forming eruption vented the upper portions of the reservoir that were zircon saturated. Subsequently, deeper “remnant” dacite magma previously outside the zone of zircon saturation but crystallizing other major phases, rose to re-establish lithostatic equilibrium, commenced zircon crystallization anew, and drove resurgent volcanism and uplift. This ~1.1 Myr zircon crystallization history records the minimum duration of the lifetime of the PGI supereruption magma from its accumulation to post-climactic solidification. These data support >1 Myr magma lifetimes and a link between volcanic and plutonic realms in large sub-caldera magma reservoirs in the uppermost crust that feed some supereruptions. Close