245 Rock Deformation and the Dynamics of Mountain Building: A Session Honoring the Scientific Contributions of John P. Platt, Part I

We welcome contributions inspired by the diverse research of John Platt in structural geology and tectonics showing how the rock record can be used to illuminate the fundamental processes of crustal deformation and mountain building.

Wednesday, 22 October 2025
8:00 AM - 12:00 PM
HBGCC, 217D

Reconstructing Farallon subduction history from mantle slabs and correlating to the rock record

Paper number: 245-9
Program: Technical Sessions
Time: 10:10 AM – 10:25 AM

Authors

Abstract

We map fast velocity anomalies in the uppermost 900-1200 km of the mantle under modern-day North America and central America to correlate Farallon subduction history to the rock record.  Slabs are mapped in 3D from recent P- and S-wave full waveform tomography SATONA (Hua et al., 2025) and compared to our mapped slabs from a previous generation of published P- and S-wave teleseismic tomography (Schmandt and Lin, 2014). Preliminary results from mapping of Schmandt and Lin (2014) tomography shows an overall slab sheet that spans from the modern Cascadia subduction zone to the US East Coast. Two large gaps in the slab sheet are centered near Wyoming-Idaho and Texas to Illinois.  Alongside these gaps, we identified a slab gap beneath California-Nevada that appears to be related to the California slab window.  Initial slab maps corroborate forward geodynamic models from Liu and Stegman (2011) with the apparent presence of a ‘horseshoe’ shaped fast velocity anomaly beneath Nevada-Utah-Arizona.  Preliminary slab mapping from SATONA tomography shows tearing within the Cascadia slabs that we compare to the Cascadia magmatic arc record and Yellowstone hotspot.  We mapped the Cocos slab from the modern-day subduction zone to the U.S Gulf coast using SATONA to distinguish between potential Cocos and Farallon fast velocity anomalies under North America. The Cocos slabs appear more highly fragmented in SATONA that previous imaging, which aligns with forward geodynamic models from (e.g. Xue et al., 2023; Wang et al., 2025). We aim to correlate our interpretations with Laramide arc migration patterns.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413764

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