Sugan Lake, China 850 Year Ostracod Geochemical Data Zhang, J.-W.; Holmes, J.A.; Chen, F.-H.; Qiang, M.; Zhou, A.F.; Chen, S. Zhang, J.-W. Holmes, J.A. Chen, F.-H. Qiang, M. Zhou, A.F. Chen, S. hydrology earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (magnesium/calcium,ostracod,null,dimensionless,null,paleolimnology,null,null,N,Eucypris inflata) earth science/paleoclimate/paleolimnology (strontium/calcium,ostracod,null,dimensionless,null,paleolimnology,null,null,N,Eucypris inflata) earth science/paleoclimate/paleolimnology (delta 18O,ostracod,null,per mil VPDB,null,paleolimnology,null,null,N,Eucypris inflata) earth science/paleoclimate/paleolimnology (age,null,null,year Common Era,null,paleolimnology,null,null,N,varve counting) earth science/paleoclimate/paleolimnology (delta 13C,ostracod,null,per mil VPDB,null,paleolimnology,null,null,N,Eucypris inflata) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Sugan Lake>LATITUDE 38.8667>LONGITUDE 93.8833) The Mg, Sr and Ca contents of single shells of the ostracod Eucypris inflata from sediments retrieved from Sugan Lake, on the northern Tibetan Plateau, were analysed in order to reconstruct the salinity changes during the past ~850 yr. At present, the lake water has a Mg/Ca ratio >40 and carbonates precipitated in the lake in the summer are mainly monohydrocalcites. However, X-ray diffraction analysis of core sediments suggests that several carbonate phases, including aragonite and even possibly dolomite, may have precipitated in the past. During the period (before 1620 AD) when there was aragonite precipitation, the Sr/Ca ratios of ostracod shells were at a minimum and showed little variation. When there was no aragonite precipitation (after 1620 AD), the Sr/Ca ratios of ostracods may have reflected salinity changes. The generally low Mg/Ca ratios during most of the past 850 yr may have resulted from decreased Mg partitioning in high-Mg/Ca host water as ostracods physiologically exclude excess Mg. Therefore, the Mg/Ca of ostracods cannot be used as a salinity proxy. The short-lived Mg/Ca maxima after 1300 AD correspond to decreased Sr/Ca and oxygen isotopes, indicating brief periods of freshwater input. The peaks of Mg/Ca ratios showed a similar variation with temperature change during the past 700 yr, indicating possible temperature dependence during times when the Mg/Ca ratio of the water was reduced. Water chemistry, temperature and mineralogical processes may have all affected the trace-element ratios of ostracods. Combined Sr/Ca ratios, carbonate mineralogy and oxygen isotopes allowed the lake's salinity to be reconstructed during the past ~850 yr. In enclosed lakes in hyper-arid regions, especially in high-Mg/Ca waters, the trace-element chemistry of ostracod shells should be treated with care and the complex controls on trace-element should be examined before paleosalinity or paleotemperature reconstruction is attempted. STUDY NOTES: Ostracod shell oxygen isotope and trace element data from Sugan Lake core SG00C, Qaidam Basin, China. The sediments from this lake are annually laminated: varve counts were undertaken on a parallel core SG00I and correlation between SG00C and GC00I based on bulk carbonate oxygen isotope variations was used to develop a chronology for SG00C. The stable isotope time series was originally described in Holmes et al., (2007) Geophy. Res. Lett. 34, L23403, doi:10.1029/2007GL032228. Note that the carbon isotope data in this dataset were not described in this publication and remain unpublished. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Zhang, J.-W. Investigator : Holmes, J.A. Investigator : Chen, F.-H. Investigator : Qiang, M. Investigator : Zhou, A.F. Investigator : Chen, S. 2013-05-17 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/14448 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/china/sugan2009elements.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/china/sugan2009isotopes.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/china/sugan2009elements.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/china/sugan2009isotopes.txt English https://www.ncdc.noaa.gov/paleo/study/14448 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/china/sugan2009elements.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/china/sugan2009isotopes.txt Jiawu Zhang, Jonathan A. Holmes, Fahu Chen, Mingrui Qiang, Aifeng Zhou, Shuo Chen. 2009. An 850-year ostracod-shell trace-element record from Sugan Lake, northern Tibetan Plateau, China: Implications for interpreting the shell chemistry in high-Mg/Ca waters. Quaternary International, Vol. 194, Issues 1-2, pp. 119-133. DOI: 10.1016/j.quaint.2008.05.003 START YEAR: 1080 AD * END YEAR: 2000 AD 93.8833 38.8667 93.8833 38.8667