A 14 kyr record of the tropical Andes: The Lago Chungará sequence (18°S, northern Chilean Altiplano)

Abstract

High-resolution geochemical analyses obtained using an X-ray fluorescence (XRF) Core Scanner, as well as mineralogical data from the Lago Chungará sedimentary sequence in the northern Andean Chilean Altiplano (18°S), provided a detailed reconstruction of the lacustrine sedimentary evolution during the last 14,000 cal. yr BP. The high-resolution analyses attained in this study allowed to distinguish abrupt periods, identify the complex structures of the early and mid-Holocene arid intervals and to compare their timing with Titicaca lake and Sajama ice records. Three main components in the lake sediments have been identified: (a) biogenic component, mainly from diatoms (b) volcanics (ash layers) from the nearby Parinacota Volcano and (c) endogenic carbonates. The correlation between volcanic input in Lago Chungará and the total particles deposited in the Nevado Sajama ice core suggests the Parinacota Volcano as the common source. The geochemical record of Lago Chungará indicates an increase in siliceous productivity during the early Holocene, lagging behind the rise in temperatures inferred from the Nevado Sajama ice core. The regional mid-Holocene aridity crisis can be characterized as a number of short events with calcite and aragonite precipitation in the offshore lake zones.