pISSN 0705-3797 eISSN 2586-1298
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Episodes 2023; 46(1): 47-62

Published online March 1, 2023


Copyright © International Union of Geological Sciences.

Petrology and quartz grain microtextures of marine shoreline sands from the Punta Arenas area, southernmost Chile and King George Island, Antarctica and implications for their depositional history

HyeJeong Kim1,†, A Chim Lee1, Yong Il Lee1,‡, Min Kyung Lee2*

1 School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Korea
2 Division of Glacial Environment Research, Korea Polar Research Institute, Incheon 21990, Korea

Correspondence to:E-mail: mklee@kopri.re.kr
Present address: Earthquake Research Institute, the University of Tokyo, Tokyo 113-0032, Japan
GeoClew Inc., Seoul 07788, Korea

Received: December 16, 2021; Revised: April 18, 2022; Accepted: April 18, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Modal composition and quartz microtextures were analyzed to investigate the provenance tectonic setting and transport mechanism in shoreline sediments from the Punta Arenas (PA) area in the southernmost part of Chile and King George Island (KGI), West Antarctica. In the sediments from both areas, volcanic rock fragments were the predominant framework grain, and a significant amount of quartz was also found in the PA area. The provenance tectonic setting of the PA area was a recycled orogen, and that of the KGI area was a magmatic arc. Quartz grains exhibited subangular shape, medium to high relief, and mainly mechanical microtextures, which were induced by high shear stress (>80%) and high-energy percussion (<20%). The shoreline sands of the two areas did not differ significantly in the distribution of frequency of microtextures of glacial and aqueous origins, so it is interpreted that the sand sediments from both areas had similar glacial and aqueous transport histories. The percussion microstructures, which occurred in less than 20% of the sands in both areas, may be due to the relatively short residence time in the energetic aqueous conditions. The presence of weathered quartz grains fractured by glaciers indicates that they had undergone significant weathering in the preceeding warm periods. The presence of high count of pre-weathered microtextures suggests that many grains travel into glacial stream carrying the pre-weathering microfeatures, which can be recognized in the sedimentary record.