T93 Plate Tectonics Paradigm and Future Directions of Research—Discovery in Light of Its 50-Year History I

Monday, 5 November 2018
8:00 AM - 12:00 PM
Room 243

THE GEOLOGIC RECORD OF SLAB BREAK-OFF IN CONTINENTAL COLLISIONS

Paper number: T93-7
Program: Technical Sessions
Time: 9:35 AM – 9:50 AM

Authors

Abstract

Slab break-off occurs when a slab detaches from a subducting plate and sinks into the mantle. Break-off is a transient process that exerts a first-order control on the geodynamic evolution of a collisional orogen by fundamentally altering the force balance along the convergent margin, thereby triggering profound shifts in exhumation, deformation, metamorphism, and magmatism. Break-off is a key aspect of the transition from oceanic subduction to continental collision and presumably has operated since the onset of plate tectonics on Earth. However, because break-off is a transient phenomenon, it has proven difficult to study in natural settings. Here we review geologic records in regions of known or inferred break-off, together with numerical models of the break-off process, in an attempt to identify uniquely diagnostic indicators of slab break-off during continental collision.

A number of geologically observable effects have been attributed to slab break-off, including reduction in convergence rate, accelerated rock and surface uplift, changes in foreland-basin sedimentation, metamorphism, and post-collisional magmatism. Numerical modeling studies have largely focused on the conditions under which break-off occurs and how slabs detach during break-off; investigations of the geologic and geodynamic effects of break-off within collisional orogens have received less attention. While current models make specific predictions regarding geological observables, all geological processes attributed to slab break-off are non-unique and can be produced by mechanisms other than break-off. Because, there does not appear to be a single, uniquely diagnostic geologic indicator of slab break-off, the key to establishing past break-off events may be to identify co-existing suites of indices that collectively attest to slab break-off. Work focused on comparing crustal shortening histories with the spatial patterns and temporal evolution of rock and surface uplift during break-off appears to be a fruitful direction for future research focused on identifying past episodes of slab break-off.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-324942

© Copyright 2018 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.