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为揭示循化盆地沉积物对古气候及青藏高原隆升过程的指示作用,采用X射线衍射(XRD)、扫描电子显微镜(SEM)方法对循化盆地中新世沉积物中粘土矿物组成、微观形貌进行了深入研究.结果表明,沉积物中粘土矿物以伊利石、蒙脱石为主,绿泥石、高岭石和坡缕石含量较低;粘土矿物相对含量及伊利石结晶度变化特征指示,在23.1～21.2Ma期间,古气候以温暖潮湿为主;21.2～14.3Ma期间古气候以冷干为主,出现短暂的相对暖湿时段;14.3～10.6Ma期间,古气候以相对暖湿为主;10.6～9.3Ma时期,气候以冷干为主;9.3～5.2Ma期间,气候虽有冷干与暖湿波动,但总体上以暖湿为主.在21.2Ma和5.8Ma时期发生的明显强降温事件,可能与青藏高原的阶段性隆升有关.
In order to reveal the paleoclimate of the Xunhua Basin and the indication of the paleoclimate and the uplift of the Qinghai-Tibet Plateau, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the composition of clay minerals in the Miocene sediments in the Xunhua Basin. The results show that the clay minerals in the sediments are mainly illite and montmorillonite, while the content of chlorite, kaolinite and palygorskite is low. The relative content of clay minerals and the change of crystallinity of illite The paleoclimate was mainly warm and humid during the period of 23.1 ~ 21.2Ma. The paleoclimate was mainly cold and dry during 21.2 ~ 14.3Ma, with a relatively short period of warm and humid period. During the period of 14.3 ~ 10.6Ma, paleoclimate was relatively warm and humid Mainly in the period of 10.6 ~ 9.3Ma, while in the period of 9.3 ~ 5.2Ma, although the climate is cold and warm and wetly fluctuant, it is generally dominated by warm and humid climate during 21.2Ma and 5.8Ma Significantly strong cooling events may be related to the stage of the Tibetan Plateau uplift.