Monitoring Cenozoic climate evolution of northeastern Tibet: stable isotope constraints from the western Qaidam Basin,China |
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| Authors: | Andrea B Rieser Ana-Voica Bojar Franz Neubauer Johann Genser Yongjiang Liu Xiao-Hong Ge Gertrude Friedl |
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| Institution: | (1) Division General Geology and Geodynamics, University of Salzburg, Hellbrunnerstr. 34, 5020 Salzburg, Austria;(2) Institute of Earth Sciences, University of Graz, Heinrichstr. 26, 8010 Graz, Austria;(3) College of Earth Sciences, Jilin University, Jianshe Str. 2199, 130061 Changchun, China;(4) Present address: Nagra, Hardstrasse 73, 5430 Wettingen, Switzerland |
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| Abstract: | Carbon and oxygen stable isotopic composition of Cenozoic lacustrine carbonates from the intramontane Qaidam Basin yields
cycles of variable length and shows several distinct events driven by tectonics and climate changes. From Eocene to Oligocene,
the over-all trend in the δ13C composition of lacustrine carbonates shows a shift toward higher values, possibly related to higher proportions of dissolved
inorganic carbon transported to the lake or lower input of soil derived CO2. At the same time, the δ18O composition of lacustrine carbonates is decreasing in accordance with the global cooling trend and northwards drifting of
the whole region. During the Miocene, distinct isotopic events can be recognized, although their interpretation and linkage
to a certain tectonic event remains difficult. These events may be related to uplift in the Himalayas, to the strongest phase
of uplift in the Altyn Mountains, to pronounced subsidence of the Qaidam Basin or to the expansion of C4 plants on land. Generally
cold, highly evaporative conditions can be deduced from enrichment of δ18O isotopic compositions during Pliocene and Quaternary times. |
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| Keywords: | Stable isotopes Intracontinental basin Climate change Evaporation Lacustrine carbonate |
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