基于成因-环境原则和多指标综合原则,依据昆仑山垭口地区的冰川地貌特征、冰碛物特征和孢粉信息,重建了该地区古环境演化历史。其中,冰碛物中的石英砂扫描电镜结果揭示了冰川、流水、风等地质营力对冰碛物的影响,孢粉分析结果在一定程...基于成因-环境原则和多指标综合原则,依据昆仑山垭口地区的冰川地貌特征、冰碛物特征和孢粉信息,重建了该地区古环境演化历史。其中,冰碛物中的石英砂扫描电镜结果揭示了冰川、流水、风等地质营力对冰碛物的影响,孢粉分析结果在一定程度上可以恢复当时的植被类型。根据垭口冰碛ESR年龄280 ka B.P.和冰碛剖面特征,将其时代暂定为300～260 ka B.P.;根据纳赤台地区的冰川地貌和沉积物特征,确定纳赤台后沟沉积为冰水扇沉积,纳赤台冰期为600～400 ka B.P.;根据玉虚峰U形谷两道侧碛垄的ESR和OSL年龄将其时代暂定为末次冰期早-中期。结合前人的研究成果,将昆仑山垭口地区的冰期序列厘定为望昆冰期(700～500 ka B.P.)、纳赤台冰期(600～400 ka B.P.)、垭口冰期(300～260 ka B.P.)、玉虚峰冰期(115～44 ka B.P.)、本头山冰期(20～13 ka B.P.)。展开更多
The Quaternary was the main evaporite deposition period in the Qaidam Basin(QB), but the correlation between the evaporite deposition period and the glacial period is still unclear. In this study, the research objects...The Quaternary was the main evaporite deposition period in the Qaidam Basin(QB), but the correlation between the evaporite deposition period and the glacial period is still unclear. In this study, the research objects are primarily evaporite-bearing strata in a 461.58 m-long drill core in the QB. X-ray powder diffraction(XRD) and scanning electron microscopy(SEM) were applied to study the evaporite minerals, U-Th dating being applied to construct the ~(230)Th geochronological framework. Evaporite deposition from Marine Isotope Stage(MIS) 15 to MIS 4 in the borehole was reconstructed via mineralogical and geochronological data. The evaporite minerals are mainly halite(NaCl), mirabilite(Na_(2)SO_(4)·10H_(2)O), thenardite(Na_(2)SO_(4)) and gypsum(CaSO_(4)·2H_(2)O). A total of 9 effective ~(230)Th data points, ranging from 492.5 ± 43.0 ka to 62.0 ± 11.9 ka, were obtained. The depositional age of the earliest halite layer in the borehole is 592.5–563.0 ka. There were mirabilite deposits in the QB during the cold glacial environment of MIS 6. During MIS 4, the study area desiccated, with mirabilite and halite being deposited. This study suggests that mirabilite is an indicator mineral for the glacial environment in the QB, while halite deposition does not correspond well to glaciation.展开更多
文摘基于成因-环境原则和多指标综合原则,依据昆仑山垭口地区的冰川地貌特征、冰碛物特征和孢粉信息,重建了该地区古环境演化历史。其中,冰碛物中的石英砂扫描电镜结果揭示了冰川、流水、风等地质营力对冰碛物的影响,孢粉分析结果在一定程度上可以恢复当时的植被类型。根据垭口冰碛ESR年龄280 ka B.P.和冰碛剖面特征,将其时代暂定为300～260 ka B.P.;根据纳赤台地区的冰川地貌和沉积物特征,确定纳赤台后沟沉积为冰水扇沉积,纳赤台冰期为600～400 ka B.P.;根据玉虚峰U形谷两道侧碛垄的ESR和OSL年龄将其时代暂定为末次冰期早-中期。结合前人的研究成果,将昆仑山垭口地区的冰期序列厘定为望昆冰期(700～500 ka B.P.)、纳赤台冰期(600～400 ka B.P.)、垭口冰期(300～260 ka B.P.)、玉虚峰冰期(115～44 ka B.P.)、本头山冰期(20～13 ka B.P.)。
基金supported by the National Natural Science Foundation of China (Grant Nos. 41902190 and 42003044)the Geological Survey Project of China (Grant No. DD20221913)the Qinghai Geological Exploration Fund (Grant No. 2020021068kc035)。
文摘The Quaternary was the main evaporite deposition period in the Qaidam Basin(QB), but the correlation between the evaporite deposition period and the glacial period is still unclear. In this study, the research objects are primarily evaporite-bearing strata in a 461.58 m-long drill core in the QB. X-ray powder diffraction(XRD) and scanning electron microscopy(SEM) were applied to study the evaporite minerals, U-Th dating being applied to construct the ~(230)Th geochronological framework. Evaporite deposition from Marine Isotope Stage(MIS) 15 to MIS 4 in the borehole was reconstructed via mineralogical and geochronological data. The evaporite minerals are mainly halite(NaCl), mirabilite(Na_(2)SO_(4)·10H_(2)O), thenardite(Na_(2)SO_(4)) and gypsum(CaSO_(4)·2H_(2)O). A total of 9 effective ~(230)Th data points, ranging from 492.5 ± 43.0 ka to 62.0 ± 11.9 ka, were obtained. The depositional age of the earliest halite layer in the borehole is 592.5–563.0 ka. There were mirabilite deposits in the QB during the cold glacial environment of MIS 6. During MIS 4, the study area desiccated, with mirabilite and halite being deposited. This study suggests that mirabilite is an indicator mineral for the glacial environment in the QB, while halite deposition does not correspond well to glaciation.
