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主要对白令海南部IODP U1340井位上新世以来(~4.3 Ma)的粘土矿物组合和结晶学特征进行了分析,探讨了研究井位中粘土矿物的物质来源及其记录的古气候变化历史.结果表明,U1340井位中的粘土矿物组合以伊利石占绝对优势(平均含量为70%),蒙脱石和绿泥石次之(平均含量分别为17%和10%),高岭石含量很低(平均含量3%).研究井位中粘土矿物组合及其物源区主要受气候特征的影响,在温暖气候时期(如9.21 ka以来)主要来自邻近的阿留申岛弧,蒙脱石含量较高;而冷气候时期(如2.74~1.07 Ma)主要源自阿拉斯加大陆,伊利石和绿泥石含量升高.利用蒙脱石/(伊利石+绿泥石)比值及伊利石和蒙脱石的结晶学特征较好地揭示了白令海南部的古气候变化历史:白令海南部在4.3~3.94 Ma以暖湿气候为主,3.94~3.6 Ma则主要受到干冷气候的控制,同时阿留申岛弧火山作用在这一时期加强;此后逐渐向冷湿气候转变,至2.74 Ma受北半球冰川作用的影响气候再次呈现干冷的特征;1.95 Ma开始逐渐向冷湿气候过渡,经历1.07~0.8 Ma中更新世气候转型之后,白令海南部主要受控于冷湿气候,但在~0.42 Ma(MIS 11),~0.33 Ma(MIS 9)及~0.12 Ma(MIS 5),气候相对温暖,化学风化作用加强;~9.21 ka全新世以来白令海南部以相对的暖湿气候为主.
Clay mineral assemblages and crystallographic characteristics of the IODP U1340 well in the southern part of the Bering Sea since the Pliocene (~ 4.3 Ma) were analyzed. The source of clay minerals in the study wells and their recorded history of paleoclimate changes were discussed. The results show that clay mineral assemblages in U1340 well dominated by illite with an average content of 70%, followed by montmorillonite and chlorite (with an average content of 17% and 10% respectively), and kaolinite content was very high Low (average 3%). The clay mineral assemblages and their provenance areas in the study well are mainly affected by the climatic characteristics and mainly come from the adjacent Aleutian island arc during the warm climate (since 9.21 ka) While the cold climate period (eg, 2.74-1.07 Ma) mainly originated from the Alaskan continent, and the content of illite and chlorite increased.Using the ratio of montmorillonite / (illite + chlorite) and the contents of illite and montmorillonite Crystallographic features reveal the history of paleoclimate changes in the southern Bering Sea well: warm and humid climate is dominant in 4.3 ~ 3.94 Ma in the southern Bering Sea, 3.94 ~ 3.6 Ma is mainly controlled by dry and cold climate, while Aleutian Island The role of arc volcanoes intensified during this period; thereafter gradually to cold and wet (2.74 Ma). The climate affected by the glaciation in the northern hemisphere once again showed a dry and cold climate. 1.95 Ma started to gradually transition to cold and wet climate. After the mid-Pleistocene climate transition from 1.07 to 0.8 Ma, the southern Bering Sea was mainly controlled by cold and wet Climate, but with a relatively warm climate and enhanced chemical weathering at ~ 0.42 Ma (MIS 11), ~ 0.33 Ma (MIS 9) and ~ 0.12 Ma (MIS 5). Since the Late Pleistocene ~ 9.21 ka Holocene, the relative Warm and humid climate-based.