大厂凹陷MIS3阶段以来沉积物地球化学特征分析

深海氧同位素3-1阶段是指深海沉积物有孔虫氧同位素记录的第四纪末次冰期至冰后期的一个时期，期间气候表现为间冰阶、极端寒冷、多次千年尺度气候事件至最后转暖多个变化特征，相关气候变化沉积响应及影响因素等科学问题一直以来备受关注。然而，该时期相关千年尺度气候事件的记录及讨论在华北平原地区仍有争议，为探讨华北平原西北地区在该阶段的气候特征，本研究在大厂凹陷区天然剖面进行高密度碳14断代样品测试，并开展常量和微量元素地球化学含量分析，获得地球化学数据变化趋势特征，结果表明，该剖面年代从32.5ka至8.2 ka，处于深海氧同位素3阶段末期至深海氧同位素1阶段早期。在该时段，主量元素氧化物TFe2O3、Al2O3、SiO2、MgO、CaO、Na2O与K2O与微量元素Sr、V、Ni、Co、Ga、Cu、Ba、Cr和Zn均呈现一致的变化趋势；在MIS2末次冰盛期和MIS1早期中的B?lling-Aller?d暖期和新仙女木冷期，K/Na、Al/Na、化学蚀变指数 、化学风化指数 和古温度等指标与东亚季风区气候呈现一致的变化，同时与全球尺度的事件具有同步性，因此认为晚更新世晚期华北平原的气候变化可归因于全球气候系统下东亚季风区的演化。

Geochemical characteristics of sediments in Dachang sag since the MIS3 stage

The Marine Oxygen Isotope (MIS3-1) stage refers to a period from the last glacial period to the post glacial period recorded by foraminiferal oxygen isotopes in deep-sea sediments. During this period, the climate is characterized by inter-glacial stage, extreme cold, several thousand-year scale climate events to the final warming, and related scientific issues such as the sedimentary response and influencing factors of climate change have always been attracted attention. However, the record and discussion of the Millennium-scale climate events in this period are still controversial in North China Plain. In order to discuss the climatic characteristics of the northwest area of the North China Plain at this stage, high-density 14C dating samples were tested in the natural profile of Dachang sag, and the major and trace element geochemical content analysis was carried out to obtain the trend characteristics of geochemical data. The results show that the age of the profile range from 32.5 ka to 8.2 ka, which corresponds from the late MIS3 stage to the early MIS1 stage. During this period, the major element oxides TFe2O3, Al2O3, SiO2, MgO, CaO, Na2O and K2O show the same change trend with the trace elements Sr, V, Ni, Co, Ga, Cu, Ba, Cr and Zn; During the last glacial maximum of MIS2 and the B?lling-Aller?d warm period and the Younger Dryas cold period in the early MIS1 stage, indicators such as K/Na, Al/Na, Chemical Index of Alteration (CIA), Chemical index of weathering (CIW), and paleotemperature are related to the East Asian monsoon climate. Therefore, it is believed that the climate change in the North China Plain in the late Pleistocene can be attributed to the evolution of the East Asian monsoon region under the global climate system.