Location
Toomey Hall, Room 199
Presentation Date
April 22, 2023, 12:00pm - 1:10pm
Session
Session 6s
Description
Between 12-25°S latitude there is prolific volcanism fueled by the Altiplano-Puna Magmatic Body (APMB), a mid-crustal magma body above the 30° subduction of the Nazca plate and within 70-80 km thick South American crust. Cerro Uturuncu, the volcano directly above the APMB, demonstrates that the APMB experiences considerable mixing with the surrounding continental crust. Within the past 1 Ma, Uturuncu has experienced six distinct stages of andesitic to dacitic lava. With this research, we contribute greater understanding to the homogenization of and mixing within the APMB and comment on how this relates to magma residence times. The influx and recharge of new mafic material, in addition to supplementary crustal partial melt, changes the APMB composition continuously over time. While previous research on Uturuncu has focused on whole-rock geochemistry, we evaluate individual sub-crystal geochemistry and geochronometry. Major element, trace element, textural classification, and Sr diffusion modeling was performed on eight Cerro Uturuncu samples representing the four largest lava stages in Uturuncu history using the LA-ICP-MS, EPMA, optical microscopy, and Lubbers et al. (2022) trace element diffusion across plagioclase python script. Overall, we found that in the past 1 Ma, the magma chamber architecture below Cerro Uturuncu condensed while the magma itself became increasingly homogenous through mixing events. The magma was stored at or above plagioclase closure temperatures for under 1000 yrs prior to eruption.
Meeting Name
32nd Annual Spring Meeting of the NASA-Mo Space Grant Consortium
Document Type
Presentation
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2023 The Authors, all rights reserved.
Dynamics and Timescales of Magmatic Processes at Cerro Uturuncu, Bolivia
Toomey Hall, Room 199
Between 12-25°S latitude there is prolific volcanism fueled by the Altiplano-Puna Magmatic Body (APMB), a mid-crustal magma body above the 30° subduction of the Nazca plate and within 70-80 km thick South American crust. Cerro Uturuncu, the volcano directly above the APMB, demonstrates that the APMB experiences considerable mixing with the surrounding continental crust. Within the past 1 Ma, Uturuncu has experienced six distinct stages of andesitic to dacitic lava. With this research, we contribute greater understanding to the homogenization of and mixing within the APMB and comment on how this relates to magma residence times. The influx and recharge of new mafic material, in addition to supplementary crustal partial melt, changes the APMB composition continuously over time. While previous research on Uturuncu has focused on whole-rock geochemistry, we evaluate individual sub-crystal geochemistry and geochronometry. Major element, trace element, textural classification, and Sr diffusion modeling was performed on eight Cerro Uturuncu samples representing the four largest lava stages in Uturuncu history using the LA-ICP-MS, EPMA, optical microscopy, and Lubbers et al. (2022) trace element diffusion across plagioclase python script. Overall, we found that in the past 1 Ma, the magma chamber architecture below Cerro Uturuncu condensed while the magma itself became increasingly homogenous through mixing events. The magma was stored at or above plagioclase closure temperatures for under 1000 yrs prior to eruption.
