Ahung Co, Tibet Holocene Sediment Geochemistry Morrill, C.; Overpeck, J.T.; Cole, J.E.; Liu, K.-B.; Shen, C.; Tang, L. Morrill, C. Overpeck, J.T. Cole, J.E. Liu, K.-B. Shen, C. Tang, L. earth science/paleoclimate/paleolimnology (organic carbon,sediment,null,percent,null,paleolimnology,null,carbon coulometry,N,null) earth science/paleoclimate/paleolimnology (delta 18O,carbonate,null,per mil PDB,null,paleolimnology,corrected,isotope ratio mass spectrometry,N,corrected for dolomite) earth science/paleoclimate/paleolimnology (dolomite,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,composite depth) earth science/paleoclimate/paleolimnology (principal component,null,null,dimensionless,null,paleolimnology,null,null,N,PC#2 of multiple geochemical proxies) earth science/paleoclimate/paleolimnology (delta 18O,carbonate,null,per mil PDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 13C,carbonate,null,per mil PDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (carbon/nitrogen,sediment,null,dimensionless,null,paleolimnology,null,elemental analysis,N,null) earth science/paleoclimate/paleolimnology (delta 13C,organic matter,null,per mil PDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (principal component,null,null,dimensionless,null,paleolimnology,null,null,N,PC#1 of multiple geochemical proxies) earth science/paleoclimate/paleolimnology (principal component,null,null,dimensionless,null,paleolimnology,null,null,N,PC#3 of multiple geochemical proxies) earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,actual depth) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (carbonate,sediment,null,percent,null,paleolimnology,null,carbon coulometry,N,null) earth science/paleoclimate/paleolimnology (Ahung Co>LATITUDE 31.62>LONGITUDE 92.06) We present a record of monsoon variations for the early and middle Holocene that is inferred from the geochemistry of sediment cores from Ahung Co, a lake in central Tibet. The resolution of this record is better than 50 years and the age model is derived from radiocarbon ages of terrestrial charcoal, which eliminates errors associated with the lake hard-water effect. We made down-core geochemical measurements of: % carbonate, % organic carbon, C/N and d13C of bulk organic matter, d13C and d18O of carbonate, and % dolomite. Proxy calibration and modern water-balance reconstruction show that these are proxies for lake depth and the amount of monsoon precipitation. We find that lake level and monsoon precipitation have been decreasing at Ahung Co since the early Holocene (~7500 cal yr BP). Superimposed on this trend are rapid declines in monsoon rainfall at 7000-7500 and 4700 cal yr BP and seven century-scale wet-dry oscillations. The cores do not contain sediment from the last ~4000 years. Surface sediments from the lake accumulated during the 20th century, however. From this, we argue that lake levels have risen again recently following a late Holocene dry period. STUDY NOTES: Geochemical data from cores 2A, 3A and 4A from Ahung Co, Tibet NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Morrill, C. Investigator : Overpeck, J.T. Investigator : Cole, J.E. Investigator : Liu, K.-B. Investigator : Shen, C. Investigator : Tang, L. 2006-03-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/5451 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/tibet/ahungco2006.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/tibet/ahungco2006.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/tibet/ahungco2006.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/tibet/ahungco2006.txt English https://www.ncdc.noaa.gov/paleo/study/5451 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/tibet/ahungco2006.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/asia/tibet/ahungco2006.txt Morrill, C., J.T. Overpeck, J.E. Cole, K.-B. Liu, C. Shen, L. Tang. 2006. Holocene variations in the Asian monsoon inferred from the geochemistry of lake sediments in central Tibet. Quaternary Research Vol. 65, pp. 232-243 START YEAR: 9494 cal yr BP * END YEAR: 3887 cal yr BP 92.06 31.62 92.06 31.62