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130-11 Understanding Rock Strength in a Collisional Orogen: Field and Laboratory Measurements of Rock Strength in Taiwan

Session: Evolution of Orogenic Belts Through Time: Insights from Sedimentation, Deformation, Magmatism, and Metamorphism, Part II

Presenting Author:

Leah Youngquist

Authors:

Youngquist, Leah¹, Fisher, Donald M.², DiBiase, Roman³, Yeh, En-Chao⁴

(1) Penn State, State College, PA, USA; Washington and Lee University, Lexington, VA, USA, (2) Pennsylvania State University, University Park, PA, USA, (3) Penn State, State College, PA, USA, (4) Earth Sciences Department, Taipei, Taiwan,

Abstract:

Rock strength is an important characteristic of a landscape that directly connects subsurface exhumation history to surface processes, as rock properties like mineralogy, crystallinity, and fabric are developed during exhumation. To better understand the way exhumation history controls rock strength, and how that might be manifest in landscape form, this study focuses on a north-south transect of samples in the Eastern Central Range to highlight trends related to the southward-propagation of the collision responsible for the orogen there. We present both field and laboratory measurements of rock strength in Taiwan, using a Schmidt hammer and uniaxial compression tests respectively. These strength measurements are additionally paired with microstructural analysis to connect material properties to exhumation history. We find there is significant variability in rock strength between and within rock types in both field and laboratory measurements at any given latitude. However, there is a statistically significant north-to-south trend towards weaker rocks, despite the overlap. Previous work has highlighted a geomorphic trend in which channel steepness is correlated to boulder size, and boulders decrease in size from north to south. This trend has been suggested as being the result of variable rock strength, driven by variable exhumation depth as the site of active collision in Taiwan propagates towards the south. Our paired strength and microstructural analysis here supports this hypothesis, as the strongest rocks tend to correspond to deeper exhumation conditions, although the role of inherent planes of weakness (e.g., foliation) may be important when comparing intact rock strength to exhumation conditions.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11074

Understanding Rock Strength in a Collisional Orogen: Field and Laboratory Measurements of Rock Strength in Taiwan

Description

Session Format: Oral

Presentation Date: 10/20/2025

Presentation Start Time: 04:25 PM

Presentation Room: HBGCC, 217C

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