Keche Lake, Alaska 3500 Year Multiproxy Sediment Data Chipman, M.L.; Clegg, B.F.; Hu, F.S. Chipman, M.L. Clegg, B.F. Hu, F.S. Arctic PAGES Arctic 2k earth science/paleoclimate/paleolimnology (age at sample end,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (volume magnetic susceptibility,sediment,null,dimensionless (SI system),null,paleolimnology,null,magnetic susceptibility measurement with ring or loop sensor,N,x10-6 units) earth science/paleoclimate/paleolimnology (calcite,sediment,null,weight percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (depth at sample start,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (quartz,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 18O,carbonate,null,per mil VPDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,charophyte encrustation) earth science/paleoclimate/paleolimnology (illite,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (density,sediment,null,gram per cubic centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (organic matter,sediment,null,weight percent,null,paleolimnology,null,loss on ignition,N,loss on ignition: 550 degrees Celsius for 2 hours) earth science/paleoclimate/paleolimnology (plagioclase feldspar series,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (depth at sample end,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (sedimentation rate,null,null,centimeter per year,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 13C,carbonate,null,per mil VPDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 13C,carbonate,null,per mil VPDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,charophyte encrustation) earth science/paleoclimate/paleolimnology (mineral index,sediment,null,weight percent,null,paleolimnology,null,x-ray diffraction,N,clay minerals) earth science/paleoclimate/paleolimnology (mineral index,sediment,null,weight percent,null,paleolimnology,null,x-ray diffraction,N,quartz plus plagioclase plus potassium feldspar) earth science/paleoclimate/paleolimnology (age at sample start,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (calcium carbonate,sediment,null,weight percent,null,paleolimnology,null,loss on ignition,N,loss on ignition: 950 degrees Celsius for 4 hours) earth science/paleoclimate/paleolimnology (dolomite,sediment,null,weight percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (mineral index,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,illite plus smectite) earth science/paleoclimate/paleolimnology (chlorite,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (mineral matter,sediment,null,weight percent,null,paleolimnology,null,loss on ignition,N,loss on ignition: 950 degrees Celsius for 4 hours) earth science/paleoclimate/paleolimnology (delta 18O,carbonate,null,per mil VSMOW,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (kaolinite,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (potassium feldspar,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,null) earth science/paleoclimate/paleolimnology (mineral index,sediment,null,percent,null,paleolimnology,null,x-ray diffraction,N,pyrite plus marcasite) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 18O,carbonate,null,per mil VPDB,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 18O,carbonate,null,per mil VSMOW,null,paleolimnology,null,isotope ratio mass spectrometry,N,charophyte encrustation) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Keche Lake>LATITUDE 68.02>LONGITUDE -146.92) Analyses of oxygen and carbon isotopes in bulk carbonate and Chara-stem encrustations, X-ray diffraction, and sediment composition from Keche Lake offer new information on climatic change over the past ~3,400 years in northeastern interior Alaska. The d18O and dD values of water samples from the lake and its inlet streams suggest that evaporation plays an important role in determining the isotopic composition of Keche Lake water at present. However, evaporative enrichment does not appear to be a major driver of the pronounced fluctuations in the bulk-carbonate d18O record on the basis of comparison with Chara-d18O values. The d18O values of bulk carbonate in the Keche Lake sediments vary by up to 10 ‰ over the past 3,400 years, with maximum values of -12 ‰ around 3,400 cal BP and between 2,100 and 1,500 cal BP. High d18O peaks are associated with sediments dominated by quartz, feldspar, and clay minerals suggesting the influence of detrital carbonate. Multi-millennial patterns of d18O variation at Keche Lake appear to be linked with changes in watershed and sediment-depositional processes, which may be driven by varying moisture abundance associated with the position of the Aleutian Low (AL). The increasing trend of carbonate d18O from 3,400 to ~2,100 cal BP probably reflects the increasing importance of a westerly AL, and the high frequency of d18O spikes ~2,100–1,500 cal BP may have resulted from the prevalence of a westerly AL position. Predominance of a westerly AL likely increased snowfall and winter temperature in the region. Such conditions would have promoted soil erosion and thermokarst activity during spring snowmelt, resulting in episodic large influxes of detrital carbonate to Keche Lake and elevating bulk-carbonate d18O. Over the past 1,500 years, bulk-carbonate d18O remained relatively high at Keche Lake but variation was much less pronounced than before. A broad d18O peak centered ~400 cal BP may be related to enhanced winter moisture during the Little Ice Age, although our chronology is inadequate for a rigorous assessment of this interpretation. This study contributes a new d18O record and offers additional information on past moisture-regime shifts associated with changing atmospheric-circulation patterns. STUDY NOTES: Isotope, geochemical, and chronological data for Keche Lake, Alaska, for the past 3500 years. Lake water isotope, temperature, conductivity, and oxygen measurements from July 2007 also included. Keche Lake: 68.02°N, 146.92°W; 740 m a.s.l. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Chipman, M.L. Investigator : Clegg, B.F. Investigator : Hu, F.S. 2012-06-30 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/13078 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/keche2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/keche2012.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/keche2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/keche2012.xls English https://www.ncdc.noaa.gov/paleo/study/13078 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/keche2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/keche2012.xls Chipman, M.L., B.F. Clegg, and F.S. Hu. 2012. Variation in the moisture regime of northeastern interior Alaska and possible linkages to the Aleutian Low: inferences from a late-Holocene d18O record. Journal of Paleolimnology, Vol. 48, No. 1, June 2012, pp. 69-81. DOI: 10.1007/s10933-012-9599-0 START YEAR: 3393 cal yr BP * END YEAR: -57 cal yr BP -146.92 68.02 -146.92 68.02