Nuclear, Particle, Astroparticle and Cosmology (NUPAC) Seminars
Tracking Magma: Using Geochemistry to Investigate Transport Processes in the Lithosphere
Presented by Kellen Malone (UNM)
Trace element and isotopic ratios in volcanic rocks are powerful indicators of what melted and when. In Southwestern North America (SWNA) for example, the shift in tectonic setting from a subducting plate to an extending plate in the last 70 Myrs is accompanied by a shift in these geochemical indicators measured in volcanic rocks. But, this type of interpretation of geochemical data relies on the assumption that trace element and isotopic ratios are not easily modified during the transport of magma (melts) as they ascend through the lithosphere. Here, I test this assumption by considering circumstances in which melts with source-rock trace element and isotopic signatures might be “overprinted” by interactions with wall rocks as they ascend. The dynamics of these indicators during transport are modeled using a system of 1-D 2-phase advection-diffusion-exchange equations. I’ll show regimes of behavior that are governed by the strength of melt-rock exchange, what these regimes tell us about whether the common assumption that trace element geochemical indicators are not easily modified during transport is correct our not, and what implications this has for SWNA.
2:00 pm, Tuesday, March 21, 2023
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