科研之友
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摘要
Terrestrial carbonate formations, such as travertines, speleothems and lake sediments, are important archives of terrestrial climate forcing At the Sutto section in Hungary, a complex succession of travertine is covered by a loess-palaeosol sequence, both are high resolution terrestrial archives of climate and environment change. Uranium-series (Th-230/U) dating was carried out to set up a more reliable chronological frame for the travertine. As the growth of travertine is very complex, pore cements may cause serious problems for precise dating The state of alteration of primary spar and micrite was characterised by microscopic, cathodoluminescence and microprobe analyses The travertine from Sutto showed homogeneous phases of primary calcite, minor micropores and rare pore cements The carbon isotopic composition indicates that the source of carbon was a mixture of atmospheric and soil derived CO2 Calculated water temperatures based on oxygen isotope data range from 22 degrees C to 31 degrees C. An attempt to provide an independent relative dating approach by palaeomagnetic techniques failed Th-230/U ages were determined applying an isochron approach using the leachate/leachate method. As the travertine deposits have a dense structure, the bulk sampling method was successfully applied in determining uranium-series ages with much higher precision than former studies with alpha spectrometry Travertines from Sutto yielded Mid-Pleistocene ages ranging from the antepenultimate glacial to the penultimate interglacial (310-240 ka) These results are in agreement with those from optically stimulate
- 出版日期2010-8-1
