302-8 Geochemical and Mineralogical Characterization of Periglacial Soils and Provenance of Dust in the Quelccaya Ice Cap (Peru)

Session: Aeolian Systems in Time and Space (Posters)

Presenting Author:

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Abstract:

Aeolian dust emissions have doubled in the industrial era. Anthropogenic climate change has led to the exposure of new, uncharacterized dust sources such as dry lakebeds and land exposed by glacial retreat. These new dust sources add to the regional and global dust loads, increasing the uncertainty of climate models as the radiative and cloud-forming effects of aeolian dust depend on its geochemical and mineralogical composition. Tropical glaciers in the Andes Mountain range have undergone rapid retreat in the modern era, losing around 30-60% of their total area. The Quelccaya Ice Cap (QIC) has experienced a retreat of 37% of its total area in the last 40 years, exposing ~22km² of land. This land may act as a new dust source, supplying the QIC with local dust, lowering its albedo, and enhancing melting. This potential periglacial dust source is uncharacterized, however. Thus, seven periglacial soil samples, two Lake Titicaca soil samples, and three dust samples from QIC snow have been selected and analyzed for their mineralogical, morphological, and geochemical (trace (TE) and rare earth element (REE)) compositions. By comparing the profiles of potential dust sources and aeolian dust within QIC snow, the provenance of aeolian dust arriving on the QIC can be investigated. This will reveal if the growing local dust source is indeed contributing to dust within the QIC itself and thus modifying its albedo. Individual particle morphology has been obtained by Scanning Electron Microscope (SEM) imaging. Total mineralogical composition of samples has been obtained by X-ray diffraction spectroscopy and the mineralogy of individual particles has been obtained by SEM-EDS. TE and REE concentrations have been obtained by inductively coupled plasma mass spectroscopy. Finally, radiogenic ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd isotopic ratios have been obtained by TIMS. This work provides a unique dataset that will be useful in constraining the radiative and cloud-forming effects of dust sources in the northern Altiplano. Additionally, the characterization of the local QIC dust source and dust within QIC snow enables the future investigation of dust provenance within a QIC ice core.

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

doi: 10.1130/abs/2025AM-8259

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