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The palaeohydrological evolution of Lago Chungará (Andean Altiplano, northern Chile) during the Lateglacial and early Holocene using oxygen isotopes in diatom silica
Author(s) -
Hernández Armand,
Bao Roberto,
Giralt Santiago,
Leng Melanie J.,
Barker Philip A.,
Sáez Alberto,
Pueyo Juan J.,
Moreno Ana,
ValeroGarcés Blas L.,
Sloane Hilary J.
Publication year - 2008
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.1173
Subject(s) - diatom , holocene , geology , isotopes of oxygen , sediment , precipitation , deposition (geology) , paleolimnology , biogenic silica , hydrology (agriculture) , groundwater , physical geography , oceanography , environmental science , geochemistry , geomorphology , geography , geotechnical engineering , meteorology
Oxygen isotopes of diatom silica and petrographical characterisation of diatomaceous laminated sediments of Lago Chungará (northern Chilean Altiplano) have allowed us to establish its palaeohydrological evolution during the Lateglacial–early Holocene (ca. 12 000–9400 cal. yr BP). These laminated sediments are composed of light and dark pluriannual couplets of diatomaceous ooze formed by different processes. Light sediment laminae accumulated during short‐term diatom blooms whereas dark sediment laminae represent the baseline limnological conditions during several years of deposition. Oxygen isotope analysis of the dark diatom laminae show a general δ 18 O enrichment trend during the studied period. Comparison of these δ 18 O diatom values with the previously published lake‐level evolution suggests a correlation between δ 18 O diatom and the precipitation:evaporation ratio, but also with the evolution of other local hydrological factors as changes in the groundwater outflow as well as shifts in the surface:volume ratio of Lago Chungará. The lake expanded (probably increasing this ratio) during the rising lake‐level trend due to changes in its morphology, enhancing evaporation. Furthermore, the lake's hydrology was probably modified as the groundwater outflow became sealed by sediments, increasing lake water residence time and potential evaporation. Both factors could cause isotope enrichment. © Natural Environment Research Council (NERC) copyright 2008. Reproduced with the permission of NERC. Published by John Wiley & Sons, Ltd.