鲁西汶东凹陷Qk203钻孔黏土矿物特征及其古环境

Characteristics of Clay Mineral and Paleoenvironment of Qk203 Borehole in Wendong Depression in Luxi Area

摘要:

利用X射线衍射分析，对鲁西地区汶东凹陷Qk203孔沉积物中黏土矿物学特征及其古气候指示作用进行了深入研究。沉积物中黏土矿物主要为蒙脱石、高岭石和伊利石。AMS 14C测年结果、岩性组合特征、黏土矿物相对含量变化和V(Ch+I)/V(Kao+S)比值，将汶东凹陷晚更新世以来古气候环境演化划分为5个阶段，先后经历了冷干-暖湿-干凉-暖湿-进一步暖湿周期性气候旋回。其中阶段Ⅰ（2.15~0m）时代为全新世，对应于深海氧同位素MIS1（冰后期）；阶段Ⅴ～Ⅱ（33.00~2.15m）时代为晚更新世，对应于深海氧同位素MIS2（末次冰盛期），研究表明末次冰盛期以来的气候变化具有全球性，但在不同地区会有所差异，一定程度上响应于全球古气候和中国东部古气候的变化，同时表明全球性的气候变迁对我国第四纪气候的演变起到一定控制作用,而且我国独特的构造运动也在一定程度上影响着局部气候演化进程。

Abstract:

By using Xray diffraction (XRD), clay mineralogy characteristics and paleoclimate indicators of sediments in borehole Qk203 of Wendong Depression in western Shandong province have been studied. It is showed that clay minerals in the sediments are mainly montmorillonite, kaolinite and illite. Based on AMS 14C dating results of borehole Qk203, lithologic association characteristics, relative content changes of clay minerals and V(Ch+I)/V(Kao+S) ratio, paleoclimatic environment evolution since late Pleistocene in Wendong depression can be divided into five stages. It has successively experienced cold drying—warmhumid—dry and cool—warm and humid—further warm and humid cycle. Stage Ⅰ（2.15~0m）is Holocene, corresponding to deep sea oxygen isotope MIS1 (postglacial period); stage Ⅴ~Ⅱ(33.00~2.15m） is late Pleistocene, corresponding to deepsea oxygen isotope MIS2 (last glacial maximum). It is showed that the climate change since the last glacial maximum is global, but it will be different in different regions. It is in response to the changes in the global paleoclimate and the paleoclimate in eastern China to a certain extent. The global climate change has played a certain role in controlling the evolution of the climate in Quaternary in China, while unique tectonic movement in China will also affects local climate evolution process to a certain extent.