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Closed Access item The palaeohydrological evolution of Lago Chungara´ (Andean Altiplano, northern Chile) during the Lateglacial and early Holocene using oxygen isotopes in diatom silica

Authors:Hernández, Armand
Bao, Roberto
Giralt, Santiago
Leng, Melanie J.
Barker, Philips A.
Sáez, Alberto
Pueyo Mur, Juan José
Moreno Caballud, Ana
Valero-Garcés, Blas L.
Sloane, Hilary J.
Keywords:Diatom ooze, Laminated sediments, Oxygen isotopes, Rhythmites, Holocene, Andean Altiplano
Issue Date:May-2008
Citation:JOURNAL OF QUATERNARY SCIENCE 23(4): 351–363 (2008)
Abstract: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 18O enrichment trend during the studied period. Comparison of these 18Odiatom values with the previously published lake-level evolution suggests a correlation between 18Odiatom 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.
Publisher version (URL):http://www3.interscience.wiley.com/journal/118902447/abstract
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