The Records Of Climate And Environment Change In BDQ Drilling Of Hoh Xil From 0.9Ma

BDQ0608 driling from Kekexili's palaeo-lake in the Qinghai-Tibet Plateau as thick as 106.8m. This paper is based on high resolution grainsize, organic carbon isotope, total organic carbon (TOC), organic carbon to nitrogen ratios(C/N) and the analysis of archaeomagnetism index, estabilshed the drilling's palaeomagneto dating, climate and environment change sequence since the 0.9Ma. Grainsize in the long scale lake sedimentary study is very important, the high percentage of coarse silt values reflect the lake contraction and low lake level, environment was dry; the high percentage of clay reflect the lake expansion and high lake level, environment was wet. Analyse the grainsize distribution of the lake sediment, frequency distribution curve and probability cumulative curve and grain size parameter, can be more accurately reduct the enviornmental change process. BDQ0608 drilling organic carbon isotopic records and the organic carbon was opposite relativity, when the climate was warm, organic carbon isotope was negative; when the climate was cold, organic carbon isotope was high.According to Grainsize, Organic carbon isotope the comprehensive analysis of the climate, divided into nineteen stages, equivalent to 4-22 stage of deep sea oxygen isotope, reconstruction of the ancient climate evolution. (1) 926-517.7kaB.P.:this stage was cold, equivalent to 22-14 stage of deep sea oxygen isotope; lakes level changes frequently, means the environment was significant changes in wet and dry.893.1-835.6kaB.P.:temperature was lower, lake level was increased, environment change from dry to wet, climate changed from cold and wet to cold and dry; 835.6-801.5kaB.P.:temperature increased rapidly, lake was shrinked, climate was warm and dry; 801.5-734.2kaB.P.:temperature was decreased, lake level was increased, climate was cold and wet; 734.2-713.5kaB.P.:temperature increased rapid, environment was wet, climate was warm and wet; 713.5-664.4kaB.P.:temperature was low, environment was wet, the climate became cold and wet; 664.4-620.5kaB.P.:temperatures increased, lake was shrinked, environment became dry, the climate became warm and dry; 620.5-582.3kaB. P.:temperature decreased, lake was expanded, environment was wet, the climate became cold and wet; 582.3-548.4kaB.P. temperature increased, lake was shrinked, the climate became warm and dry; 548.4-517.7 kaB.P.: temperature decreased rapidly, lake was expanded, the climate became cold and wet. (2) 517.7-306.9kaB.P.:Temperature fluctuate weakly; lake's level was high, equivalent to 13-9 stage of deep sea oxygen isotope.517.7-454.5kaB.P.:temperatures increased, lake level was high, the climate became warm and wet; 454.5-411.9kaB.P.:Temperature decreased, environment was wet, the climate became cold and wet; 411.9-382.1kaB.P.:temperatures increased, environment was still wet, the climate became warm and wet; 382. 1-340kaB.P.:temperature became lower, lake level was decreased, environment was dry, climate became cold and dry; 340-306.9kaB.P.: temperature was rised, precipitation change frequently, wet and dry alternatively. (3) 306.9-137.6kaBP: temperature was dropped, equivalent to 8-6 stage of deep sea oxygen isotope; the lake water level changed very frequently, climate was changed frequently in wet and dry. 306.9-237.7kaB.P.:lower temperature, lake water level changed frequently, cold wet and cold dry alternately; 237.7-201.4kaB.P.:temperatures increased, lake water level changed frequently, alternate warm and wet to warm and dry; 193.4-137.6kaB.P.:lower temperature, lake water level was decreased, environment changed from wet to dry, climate changed from cold and wet to cold and dry. (4)137.6-75.8kaB.P.:rapid increased in temperature at this stage, equivalent to 5 stage of deep sea oxygen isotope; shallow lake level began a relatively short period, then lake water levels became high, climate changed from warm and dry to warm and wet. (5) 65.5-0kaB.P.:less temperature at this stage, the lake water level from high to low.11.12-4.55m lake's water level was high, environment was wet; while in 4.55-0m lake's water lever gradually dried up, climate changed from the wet to dry.