Centennial- to millennial-scale hard rock erosion rates deduced from luminescence-depth profiles

TY - JOUR

T1 - Centennial- to millennial-scale hard rock erosion rates deduced from luminescence-depth profiles

AU - Sohbati, Reza

AU - Liu, Jinfeng

AU - Jain, Mayank

AU - Murray, Andrew

AU - Egholm, David

AU - Paris, Richard

AU - Guralnik, Benny

PY - 2018/7

Y1 - 2018/7

N2 - The measurement of erosion and weathering rates in different geomorphic settings and over diverse temporal and spatial scales is fundamental to the quantification of rates and patterns of earth surface processes. A knowledge of the rates of these surface processes helps one to decipher their relative contribution to landscape evolution – information that is crucial to understanding the interaction between climate, tectonics and landscape. Consequently, a wide range of techniques has been developed to determine short- (<102 a) and long-term (>104 a) erosion rates. However, no method is available to quantify hard rock erosion rates at centennial to millennial timescales. Here we propose a novel technique, based on the solar bleaching of luminescence signals with depth into rock surfaces, to bridge this analytical gap. We apply our technique to glacial and landslide boulders in the Eastern Pamirs, China. The calculated erosion rates from the smooth varnished surfaces of 7 out of the 8 boulders sampled in this study vary between <0.038±0.002 and 1.72±0.04 mmka−1 (the eighth boulder gave an anomalously high erosion rate, possibly due to a recent chipping/cracking loss of surface). Given this preferential sampling of smooth surfaces, assumed to arise from grain-by-grain surface loss, we consider these rates as minimum estimates of rock surface denudation rates in the Eastern Pamirs, China.

AB - The measurement of erosion and weathering rates in different geomorphic settings and over diverse temporal and spatial scales is fundamental to the quantification of rates and patterns of earth surface processes. A knowledge of the rates of these surface processes helps one to decipher their relative contribution to landscape evolution – information that is crucial to understanding the interaction between climate, tectonics and landscape. Consequently, a wide range of techniques has been developed to determine short- (<102 a) and long-term (>104 a) erosion rates. However, no method is available to quantify hard rock erosion rates at centennial to millennial timescales. Here we propose a novel technique, based on the solar bleaching of luminescence signals with depth into rock surfaces, to bridge this analytical gap. We apply our technique to glacial and landslide boulders in the Eastern Pamirs, China. The calculated erosion rates from the smooth varnished surfaces of 7 out of the 8 boulders sampled in this study vary between <0.038±0.002 and 1.72±0.04 mmka−1 (the eighth boulder gave an anomalously high erosion rate, possibly due to a recent chipping/cracking loss of surface). Given this preferential sampling of smooth surfaces, assumed to arise from grain-by-grain surface loss, we consider these rates as minimum estimates of rock surface denudation rates in the Eastern Pamirs, China.

KW - erosion rate

KW - exposure dating

KW - luminescence

KW - OSL

KW - rock surface

KW - weathering rate

U2 - 10.1016/j.epsl.2018.04.017

DO - 10.1016/j.epsl.2018.04.017

M3 - Journal article

AN - SCOPUS:85046660339

SN - 0012-821X

VL - 493

SP - 218

EP - 230

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

ER -