摘要
Clay mineral assemblages and crystallinities in sediments from IODP Site 1340 in the Bering Sea were analyzed in order to trace sediment sources and reconstruct the paleoclimatic history of the Bering Sea since Pliocene （the last -4.3 Ma）. The re- sults show that clay minerals at Site U1340 are dominated by illite, with a moderate amount of smectite and chlorite, and minor kaolinite. Sediment source studies suggest that the clay mineral assemblages and their sources in the studied core are controlled primarily by the climate conditions. During the warm periods, clay minerals originated mainly from the adjacent Aleutian Is- lands, and smectite/（illite＋chlorite） ratios increased. During the cold periods, clay minerals from the Alaskan region distinctly increased, and smectite/（illite＋chlorite） ratios declined. Based on smectite/（illite＋chlorite） ratios and clay mineral crystallinities the evolutionary history of the paleoclimate was revealed in the Bering Sea. In general, the Bering Sea was characterized by warm and wet climate condition from 4.3 to 3.94 Ma, and then cold and dry condition associated with the enhanced volcanism from 3.94 to 3.6 Ma. Thereafter, the climate gradually became cold and wet, and then was dominated by a cold and dry condi- tion since 2.74 Ma, probably induced by the intensification of the Northern Hemisphere Glaciation. The interval from 1.95 to 1.07 Ma was a transitional period of the climate gradually becoming cold and wet. After the middle Pleistocene transition （1.07 to 0.8 Ma）, the Bering Sea was governed mainly by cold and wet climate with several intervals of warm climate at -0.42 Ma （MIS 11）, -0.33 Ma （MIS 9） and ~0.12 Ma （MIS 5）, respectively. During the last 9.21 ka （the Holocene）, the Bering Sea was characterized primarily by relatively warm and wet climatic conditions.
在从在 Bering 海的 IODP 地点 1340 的沉积的克莱矿物质集合和 crystallinities 被分析以便跟踪沉积来源并且重建 Bering 海的 paleoclimatic 历史自从上新世最后 4.3 Myr。结果证明在地点 U1340 的泥土矿物质被 illite 统治，与绿土和绿泥石的中等数量，并且次要的 kaolinite。沉积来源研究建议在学习核心的泥土矿物质集合和他们的来源首先被气候条件控制。在温暖的时期期间，泥土矿物质主要从邻近的阿留申群岛之土人岛发源，并且 smectite/illite+chlorite 比率增加了。在冷时期期间，泥土矿物质首先从阿拉斯加人区域被导出，并且 smectite/illite+chlorite 比率减少了。把比率和泥土矿物质 crystallinities 基于 smectite/illite+chlorite，古气候的进化历史在 Bering 海被揭示。一般来说， Bering 海被温暖、湿的气候状况从 4.3 ～ 3.94 Myr，然后从 3.94 ～ 3.6 Myr 与提高的火山作用联系的冷、干燥的状况描绘。此后，气候逐渐地变得冷、湿，然后自从 2.74 Myr，被一个冷、干燥的条件统治，可能由北半球冻结成冰的增强导致了。从 1.95 ～ 1.07 Myr 的间隔是逐渐地变得冷、湿的气候的一个过渡时期。在中间的更新世以后转移 1.07 ～ 0.8 Myr， Bering 海主要被冷、湿的气候分别地在 0.42 妈 MIS 11， 0.33 妈 MIS 9 和 0.12 妈 MIS 5 与温暖的气候的几间隔管理。在最后 9.21 kyr 期间 Holocene， Bering 海首先被相对温暖、湿的气候的条件描绘。
基金
supported by National Natural Science Foundation of China(Grant Nos.41476037,41076026,41276051 and 91228207)
the National Key Basic Research Program of China(Grant No.2013CB956102)
IODP-China
