循化盆地中新世沉积物粘土矿物的特征及其古气候指示  

Clay Mineralogy and Its Paleoclimatic Indicator of the Miocene Sediments of Xunhua Basin

作　　者：王粉丽[1] 洪汉烈[1,2] 殷科[1] 徐耀明[1] 张克信[1,2,3] 张楗钰[1,2] 

机构地区：[1]中国地质大学地球科学学院,湖北武汉430074 [2]中国地质大学生物地质与环境地质教育部重点实验室,湖北武汉430074 [3]中国地质大学地质调查研究院,湖北武汉430074

出　　处：《地球科学（中国地质大学学报）》2010年第5期828-838,共11页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(Nos.40921062;40872038);中国地质调查局项目(No.1212010610103);地质过程与矿产资源国家重点实验室开放课题基金项目(No.GPMR200910)

摘　　要：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.To reconstruct the paleoclimate in the Miocene, clay mineralogy of the Xunhua sediments was investigated using X-ray diffraction （XRD） and scanning electron microscopy （SEM） methods. Our results show that clay minerals of the Miocene sediments are mainly illite and smectite, with minor chlorite, kaolinite, and palygorskite. The apparent changes in their relative contents and illite crystallinity suggest that warm and humid paleoclimate conditions prevailed over the period of 23. 1- 21.2 Ma, then the mainly cold and dry climate succeeded in the period of 21.2-- 14. 3 Ma, with short intervals of warm and humid climate conditions. The mainly warm and humid climate dominated in the period of 14. 3--10. 6 Ma, and it changed into a mainly cold and dry climate in the period of 10. 6--9.3 Ma. The paleoclimate of the episode of 9. 3--5. 2 Ma was warm and humid, and it fluctuated frequently between cold/dry and warm/humid. The rapid changes in clay indices in the curves at 21.2 Ma and 5.8 Ma probably suggest the uplift in Xunhua of Qinghai-Tibet plateau.

关 键 词：粘土矿物 结晶度 中新世 循化盆地 隆升 

分 类 号：P534[天文地球—古生物学与地层学]