Rb -Sr isotopic isochron dating of the volcanic rock samples from the Upper Cretaceous Half Three Point Formation on the King George Island is 71. 33±0. 3 Ma. Correlative study of εND(T)-147Sm/144Nd, 143Nd/144Nd...Rb -Sr isotopic isochron dating of the volcanic rock samples from the Upper Cretaceous Half Three Point Formation on the King George Island is 71. 33±0. 3 Ma. Correlative study of εND(T)-147Sm/144Nd, 143Nd/144Nd-87Sr/86Sr, 87Sr/86Sr-Sr and 87Sr/86Sr-K2O/(K2O+Na2O) indicated that the volcanic rocks were chiefly derived from the depleted mantle source and generally were not mixed crust materials. Of the samples 6 were given the mean Sm -Nd model age (TDM) of 443. 3±20. 6 Ma possibly indicating the age of chemical variation event in the magma source of the study area. Features of the trace elements indicated that the rocks from the Half Three Point Formation are of typical calc-alkaline volcanic suite and similar to those from the Tertiary volcanic rocks of the Fildes Peninsula, being the same products of the island-arc volcanic activity.展开更多
通过河西走廊西部地区条湖剖面沉积物元素地球化学分析，结合高精度AMS^14C测年，探讨研究区～11400—1060 cal BP期间的气候环境演变过程。研究结果显示～11400～9400 cal BP期间，条湖处于高水位且流域内化学风化作用较强，气候条件...通过河西走廊西部地区条湖剖面沉积物元素地球化学分析，结合高精度AMS^14C测年，探讨研究区～11400—1060 cal BP期间的气候环境演变过程。研究结果显示～11400～9400 cal BP期间，条湖处于高水位且流域内化学风化作用较强，气候条件相对温暖湿润；～9400—8100 cal BP期间，湖泊水位下降，化学风化作用减弱，指示了干旱的气候条件；～8100—5800calBP气候相对湿润，其中最湿润时段出现在-8100—7200calBP之间；-5800-4800 cal BP期间，气候转干-4800 cal BP以后人类活动增强，导致区域荒漠化加剧。展开更多
酒坊台剖面位于萨拉乌苏河流域下游,其中末次间冰阶以来主要为风成砂沉积,间夹砂质古土壤和湖沼相粘土层等,对环境信息有良好的记录。OSL年龄结果表明该剖面顶部记录了末次冰期间冰阶（约52 ka B.P.）以来的气候演化历史。通过对剖面高...酒坊台剖面位于萨拉乌苏河流域下游,其中末次间冰阶以来主要为风成砂沉积,间夹砂质古土壤和湖沼相粘土层等,对环境信息有良好的记录。OSL年龄结果表明该剖面顶部记录了末次冰期间冰阶（约52 ka B.P.）以来的气候演化历史。通过对剖面高精度的粒度和磁化率分析,结合Rb、Sr元素含量及其比值综合分析,表明末次冰期间冰阶以来该剖面自上而下可划分为3个主要层段,对应了深海氧同位素MIS 1-3。同时在MIS 3阶段呈现出明显的MIS 3a、3b、3c亚段,结合区域研究资料,表明萨拉乌苏河流域在中—长时间尺度上,对全球性和区域性气候事件有良好的沉积响应。展开更多
基金The project supported by the State Antarctic Committeethe National Natural Science Foundation of China
文摘Rb -Sr isotopic isochron dating of the volcanic rock samples from the Upper Cretaceous Half Three Point Formation on the King George Island is 71. 33±0. 3 Ma. Correlative study of εND(T)-147Sm/144Nd, 143Nd/144Nd-87Sr/86Sr, 87Sr/86Sr-Sr and 87Sr/86Sr-K2O/(K2O+Na2O) indicated that the volcanic rocks were chiefly derived from the depleted mantle source and generally were not mixed crust materials. Of the samples 6 were given the mean Sm -Nd model age (TDM) of 443. 3±20. 6 Ma possibly indicating the age of chemical variation event in the magma source of the study area. Features of the trace elements indicated that the rocks from the Half Three Point Formation are of typical calc-alkaline volcanic suite and similar to those from the Tertiary volcanic rocks of the Fildes Peninsula, being the same products of the island-arc volcanic activity.
文摘通过河西走廊西部地区条湖剖面沉积物元素地球化学分析，结合高精度AMS^14C测年，探讨研究区～11400—1060 cal BP期间的气候环境演变过程。研究结果显示～11400～9400 cal BP期间，条湖处于高水位且流域内化学风化作用较强，气候条件相对温暖湿润；～9400—8100 cal BP期间，湖泊水位下降，化学风化作用减弱，指示了干旱的气候条件；～8100—5800calBP气候相对湿润，其中最湿润时段出现在-8100—7200calBP之间；-5800-4800 cal BP期间，气候转干-4800 cal BP以后人类活动增强，导致区域荒漠化加剧。
