Big Lachman´s lake sediments: role of chemical weathering

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Authors

VAŠINKA Martin KRMÍČEK Lukáš VŠIANSKÝ Dalibor HRBÁČEK Filip

Year of publication 2019
Type Conference abstract
MU Faculty or unit

Faculty of Science

Citation
Description Big Lachman Lake (Lachman I) is a shallow coastal lake located near the tip of Cape Lachman and mostly developed in the Early to mid-Holocene. The lacustrine sediment is composed dominantly of Neogene basaltic volcanic rocks of James Ross Island Volcanic Group together with Cretaceous sedimentary rocks and admixture of metasediments and granitoids derived from Antarctic Peninsula. The presence of secondary minerals, montmorillonite and kaolinite was determined by XRD diffraction in sediment and their origin in sediment is related to rocks with the same weathering rates as Lachman Lake sediment. Chemical weathering rates was calculated by the Chemical Index of Alteration (CIA) in Lachman lacustrine sediment. Nearby Neogene basalts have CIA weathering rates around optimum fresh values, whereas with Middle Jurassic rhyolites was found good correlation between CIA weathering index and chemical composition of the sediment. These rhyolites come from Antarctic Peninsula and probably were transported into the lake by small glaciers.
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