Isotope geology

Reconstruction of the last glaciation and deglaciation in the southern hemisphere through the Chilean Lake district (CHILT).

There are clear indications that major, abrupt climate changes that affected the northern hemisphere during the last glaciation and deglaciation were caused in response to more gradual changes in the southern high latitudes. In order to improve our understantding of (i) the timing and impact of climate fluctuations in both hemispheres, and the interactions between them, and (ii) the exact location of the "Southern Polar Front" during the transition between the Last Glacial Maximum and the Holocene, the CHILT project aims tostudy lake sediment records along a N-S transect through the southwestern part of South America, from the chilean Lake District (39°S) in the north to Patagonia (59°S) in the south. Long cores will be taken from Lago Villarica (39°S), around Coihaique (45-46°S) and Laguna Parillar (53°S).
After absolute dating and sedimentological, mineralogical and geochemical analyses, the cores will be analysed for biological (diatoms, chironomids, pollen) and biogeochemical (fossil pigments, TEX86 and BIT index) procies, Furthermore analyses of stable carbon and oxygen isotopic composition of ostracods, in combination with Mg/Ca and Sr/Ca ratios in the carbonates, oxygen Isotopic compostition of diatoms and isotopic composition of lake, river and meteoric water, will provide accurate information on the evolution of palaeotemperature and palaeosalinity throughout the core.