论文部分内容阅读
为重建新疆其木干地区中新世-上新世古气候,采用X射线衍射、扫描电子显微分析方法,对该区中新世-上新世沉积物中粘土矿物的相对含量、组合类型及显微形貌等进行了研究。结果显示:中新世早期-早中新世中期,沉积物中粘土矿物以伊利石和绿泥石为主,含少量的蒙脱石,表明以干旱气候为特征;晚中新世中期-早中新世晚期,伊利石的相对含量逐渐降低,且含有少量的蒙脱石和高岭石,指示相对温湿的气候条件;中新世晚期的粘土矿物组分与中新世早期相似,以伊利石和绿泥石为主,指示古气候以干旱为主导;晚中新世晚期至上新世伊利石相对含量降低,而蒙脱石和高岭石的相对含量升高,但由于粘土矿物中伊利石、绿泥石的含量仍然较高,指示古气候仍然以干旱为主导,但相对于中新世而言,这段时期为相对湿润期。以上结果表明,新疆其木干地区中新世-上新世古气候以干旱为主,并且气候经历了干旱-相对湿润-干旱-相对湿润的演化过程,但总体而言,本区中新世比上新世要更为干旱。
In order to reconstruct the Miocene-Pliocene climate in the wood-dry area of Xinjiang, the relative content of clay minerals in the Miocene-Pliocene sediments and their combination types and Micro-morphology and other research. The results show that: from the Early Miocene to Middle Miocene, clay minerals in the sediments are mainly illite and chlorite, with a small amount of montmorillonite, indicating that they are characterized by arid climate; from the middle of late Miocene to early middle Late Neocene, the relative content of illite gradually decreased, and contains a small amount of montmorillonite and kaolinite, indicating relatively warm and humid climatic conditions; late Miocene clay mineral composition similar to the early Miocene with illite and Chlorite, which indicates that the paleoclimate was dominated by drought. The relative content of illite in the late Late Miocene to the Pliocene decreased, while the relative content of montmorillonite and kaolinite increased. However, because of the illite, green The content of mudstone is still high, indicating that the paleoclimate still dominates the drought, but relative to the Miocene, this period is the relative humid period. The above results show that the predominant Pliocene-Pliocene climatic climate was dominated by its climate in the woodland region of Xinjiang, and the climate underwent arid-relative-humid-arid-relative humid evolution. However, in general, Pliocene to be more dry.