10 Evolution of Transcrustal Cordilleran Arc Systems

Wednesday, 17 May 2023
1:30 PM - 4:30 PM
Whitney Peak Ballroom 2

SUBDUCTION VELOCITY CONTROLS ON ARC MAGMATISM ALONG LONG-LIVED NE ASIA CORDILLERAN ARC SYSTEM

Paper number: 10-9
Program: Theme Sessions
Time: 3:50 PM – 4:10 PM

Authors

Abstract

The general link between subduction and arc magmatism has been widely accepted since the plate tectonics revolution; however, the evolutions in magmatic arc tempos and chemistry (e.g., wt.% SiO2) are still not fully explained. The arc crust thickness was considered a primary driver for the flare-ups and lulls, and chemical fractionation of the magmatism in long-lived cordillera arc systems, while the role of the subducting slab was not well-quantified.

This study explores the subduction velocity controls on magmatism along the 100 ~ 0 Ma NE Asia continental arc. We used statistical analysis on two paired geologic/plate tectonic datasets: (1) a large (n>500) NE Asian magmatic database of published and unpublished U-Pb zircon ages and geochemistry; and (2) plate convergence velocity extracted from a recently published, digital, fully-kinematic Eurasia-Pacific plate tectonic reconstruction (Wu et al., 2022 EPSL). The plate reconstruction model reveals ultrafast Izanagi subduction (12 to 24 cm/yr) during 100-52 Ma in contrast to slower Pacific subduction (< 8 cm/yr) during 52-0 Ma along the NE Asian margin. Comparison to NE Asia magmatism reveals the igneous rocks generated during the 100-52 Ma ultrafast subduction show high magmatic areal addition rates, high % SiO2 (mean 66-70 %), and enriched Nd isotopic ratios (-15 to +2). In comparison, igneous rocks generated during the slower 52-0 Ma subduction were characterized by lower magmatic rates, SiO2 (mean 56-63 %), and more depleted Nd isotopic ratios (-5 to +10). Linear statistical analysis shows significant correlations between subduction velocity and magmatic geochemistry with p-values lower than 0.05. We discuss the possible contribution of ultrafast subduction (>12 cm/yr) on high-flux, high-silica magmatism relative to arcs developed above more typical subduction velocities (<10 cm/yr), with implications from numerical subduction zone modeling and the modern Tonga-Kermadec arc that has along-strike subduction velocity variate from 6 to 23 cm/yr.

Geological Society of America Abstracts with Programs. Vol. 55, No. 4

doi: 10.1130/abs/2023CD-387269

© Copyright 2023 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.