[Geoldept] Invited Speaker Seminar with Rebecca Morris, Tuesday, 4/18 at 4pm, ES 100

[Geology Department]

Hi everyone,
Please join us for the Invited Speaker Seminar on Tuesday, April 18, at 4pm with Rebecca Morris (PhD candidate, University of Victoria) in ES 100. Topic: "Arc magmatism and the long-term carbon cycle: limits on the recycling of crustal carbonates"
The lecture will be in-person in ES 100 and followed by cheese and crackers from 5-6pm!

Summary: The contribution of CO2 from crustal carbonates into arc magmas is debated, as well as its role in the long-term C cycle. To better understand these contributions, studies are required on the mechanism(s) that drive CO2 production at arc settings from magma-carbonate interactions. The well-exposed Jurassic Bonanza arc on Vancouver Island (British Columbia) was built on a Triassic limestone platform and makes for an ideal field setting to examine these interactions beneath an island arc at various depths. This talk presents results from detailed magma-carbonate contacts on a variety of scales, from m-scale dikes and sills to km-scale plutons. Results show strong evidence of limestone assimilation within dikes and sills with 87Sr/86Sr ratios similar to, or on a mixing line with limestone (~0.708). In contrast, plutonic rocks show muted to no detectable interaction, where 87Sr/86Sr ratios are primary igneous values (~0.703), except for a thin (<2 m) chilled margin with elevated 87Sr/86Sr ratios (~0.706). These results indicate a far more enhanced extent of magma-carbonate interactions, and ultimately CO2 production, is via a network of shallow dikes and sills. While plutons may be an important heat source to release CO2 from carbonate wallrock (i.e., contact metamorphism), they show little (if any) limestone assimilation. These results are used to place realistic and quantitative limits on arc-derived CO2 from upper crustal sources.

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Thank you,
Hye In

Hye In Park | She/Her
Undergraduate Program Coordinator | Geology
Western Washington University
516 High Street, Bellingham WA 98225 | ES 240
parkh23 at wwu.edu<mailto:parkh23 at wwu.edu> | 360-650-6516<tel:360-650-6516> | Message me on Teams<https://teams.microsoft.com/l/chat/0/0?users=parkh23@wwu.edu>
Schedule an advising appointment with me<https://calendly.com/parkh23/geology>

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