26-3 Empirical Constraints on the Long-term Evolution of Subduction-zone Thermal Structure: P–T–t Estimates from the Cedros Island Subduction Complex, Baja California

Session: Subduction Zones and Their Volcanic Arcs: Initiation and Evolution, Structure, Metamorphism, Magmatism

Presenting Author:

Authors:

Neumann, Samuel R.¹, Xu, Yiruo², Connop, Charlotte H.³, Hernández-Uribe, David⁴, Wang, Jordan W.⁵, He, John J.Y.⁶, Kapp, Paul⁷, Worthington, James⁸

Abstract:

We present pressure–temperature estimates and geochronology for blocks of varying metamorphic grade in serpentinite-clastic matrix mélange of Cedros Island, Baja California, Mexico, to constrain changes in subduction-zone thermal structure from the Jurassic through the Cretaceous. We use this empirical dataset to test predictions from thermomechanical models for the evolution of subduction-zone thermal structure after subduction initiation. We also compare these results with compilations of comparable data along-strike (California, Oregon, Washington: USA) to evaluate changes in the evolution of a single long-lived subduction zone along strike. We then assess the uneven distribution of dates to consider possible discrete “events” of exhumation of from the subduction interface and accretion of material to the overriding plate within in the context of changes in regional tectonic stresses.

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