Class
Article
College
College of Science
Department
English Department
Faculty Mentor
Coleman Hiett
Presentation Type
Poster Presentation
Abstract
The process of flat-slab subduction introduces fluids directly into the overlaying lithosphere, leaving behind a unique stable isotope and trace element signature to the surrounding crust/mantle. Fluid alteration of the deep lithosphere can help explain geologic processes that are observed at the surface, such as patterns of crustal deformation (mountain building) and volcanism. The young high-K mafic volcanic rocks found in the Altiplano region of Southern Peru are derived from the melting of an altered mantle source. By analyzing the hydrogen stable isotopes as well as the trace elements of these volcanic rocks we can locate the water source associated with these melts and relate that to fluid alteration of the mantle appertained to ancient shallow subduction. Hydrogen stable isotopes measuring between -15‰ to -35‰ are indicative of fluids transferred from the subducting oceanic lithosphere. Values of -80 ± 10‰ indicate primary mantle hydrogen. Relatively high concentrations of fluid mobile trace elements, such as light rare earth elements (LREEs) are indicators of fluid alterations of the mantle melt source. We determined the δD values associated with the Huambutuio volcano average out to be -68.2‰ ± 1.33.While the δD values associated with the Quimsichata volcano average out to -46.03‰ ± 0.205. Previous LREE analysis of the Quimisichata volcano positively reflect the mantle presence. We can confirm the δD values of the volcanic rocks will deviate from nominal mantle values (-80 ‰ vs VSMOW) towards that of derived fluids from the subducting Nazca Plate (15‰ to -35‰), indicative of a melt source being altered by slab-derived fluids. It can be determined that the hydrous phenocrysts collected from the Huambutuio and Quimsichata are the product of mantle hydration from slab derived fluids.
Location
Logan, UT
Start Date
4-8-2022 12:00 AM
Included in
Isotopic Analysis of Hydrous Phenocrysts in Lava Flows of the Peruvian Altiplano Plateau: Testing for a Subduction Signature
Logan, UT
The process of flat-slab subduction introduces fluids directly into the overlaying lithosphere, leaving behind a unique stable isotope and trace element signature to the surrounding crust/mantle. Fluid alteration of the deep lithosphere can help explain geologic processes that are observed at the surface, such as patterns of crustal deformation (mountain building) and volcanism. The young high-K mafic volcanic rocks found in the Altiplano region of Southern Peru are derived from the melting of an altered mantle source. By analyzing the hydrogen stable isotopes as well as the trace elements of these volcanic rocks we can locate the water source associated with these melts and relate that to fluid alteration of the mantle appertained to ancient shallow subduction. Hydrogen stable isotopes measuring between -15‰ to -35‰ are indicative of fluids transferred from the subducting oceanic lithosphere. Values of -80 ± 10‰ indicate primary mantle hydrogen. Relatively high concentrations of fluid mobile trace elements, such as light rare earth elements (LREEs) are indicators of fluid alterations of the mantle melt source. We determined the δD values associated with the Huambutuio volcano average out to be -68.2‰ ± 1.33.While the δD values associated with the Quimsichata volcano average out to -46.03‰ ± 0.205. Previous LREE analysis of the Quimisichata volcano positively reflect the mantle presence. We can confirm the δD values of the volcanic rocks will deviate from nominal mantle values (-80 ‰ vs VSMOW) towards that of derived fluids from the subducting Nazca Plate (15‰ to -35‰), indicative of a melt source being altered by slab-derived fluids. It can be determined that the hydrous phenocrysts collected from the Huambutuio and Quimsichata are the product of mantle hydration from slab derived fluids.