T110 Deformation Zones in Time and Space II: A Celebration of the Career of Steven Wojtal

Monday, 10 October 2022
1:30 PM - 5:30 PM
207

DUCTILE FLOW VS. ELASTIC FLEXURE: HOW THE MECHANISM AND RATE OF ISOSTATIC SUBSIDENCE CAN INFLUENCE A FOLD AND THRUST BELTS ARCHITECTURE

Paper number: T110-10
Program: Technical Sessions
Time: 3:35 PM – 3:50 PM

Authors

Abstract

The propagation of a fold and thrust belt applies a load on the underlying crust and mantle. In warmer conditions, the lithosphere responds to this load through ductile flow, enabling Airy-like isostasy to be more prevalent in these domains. In contrast, when the fold and thrust belt evolves in cooler conditions, the lithosphere responds through elastic flexure. Here, we run a suite of high spatial resolution (80 m) geodynamic models to explore how the mechanism of isostasy and the rate of isostatic subsidence influence the architecture and structural styles of a fold and thrust belts on the 10s of km scale. Additionally, we present two numerical models to compare our results to the Subandean zone.

We find that when Airy-like isostasy is the dominant mechanism of isostasy - and with an increasing subsidence rate - fold and thrust belts are narrower and involve more complex internal architectures, including a set of sub-vertical faults that accommodate the isostatic subsidence. When the lithosphere responds through elastic flexure, fold and thrust belts are wider, higher in elevation, and involve a set of sub-horizontal faults. An increase in flexural rate does not significantly influence the first-order evolution of fold and thrust belts. Our findings are echoed in the Subandean zone, where an increase in the subsidence rate is associated with a narrower fold and thrust belt.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-378381

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