Paleoclimatic reconstruction and the response of carbonate minerals during the past 8000 years over the northeast Tibetan Plateau

Abstract

The climatic significance of the carbonate content and composition of lake sediments remains unclear. In this study, we analyzed the glycerol dialkyl glycerol tetraethers and mineral contents of Alake Lake sediments to reconstruct temperature and moisture changes over the northeast Tibetan Plateau since 8000 cal yr BP. We identified warm (cold) and wet (dry) conditions during the Roman Warm Period and Holocene Climate Optimum (Early Neoglacial Cooling Period) accompanied by a dominance of aragonite (monohydrocalcite). Based on our results and previous laboratory experiments, we suggest that monohydrocalcite is predominantly deposited in colder, drier, and higher Mg/Ca conditions relative to that of aragonite. The carbonate mineral composition should therefore be fully considered when sediment carbonate contents are used to reconstruct paleotemperature/moisture changes.