【作者】 于娜； 洪汉烈； 李朝辉； 张克信； 李荣彪；

【Author】 Yu Na~(1,2,3),Hong Han-lie~2,Li Zhao-hui~(2,4),Zhang Ke-xin~2,Li Rong-biao~2 (1.College of Earth Sciences,University of Jilin,Changchun,Jilin,130061,China;2.Faculty of Earth Sciences,China University of Geosciences,Wuhan,Hubei,430074,China;3.Faculty of Prospecting and Surveying,Changchun Institute of Technology,Changchun,Jilin,130021,China;4.Geosciences Department, University of Wisconsin-Parkside,Kenosha,WI53140,USA)

【机构】 吉林大学地球科学学院； 中国地质大学地球科学学院； 长春工程学院勘查与测绘工程学院； 威斯康星大学帕克赛德分校地球科学部；

【摘要】 临夏盆地位于中国西北部青藏高原与黄土高原衔接带上的一个晚新生代断陷盆地。该盆地是高原边缘首当其冲的构造波及区,青藏高原的隆升对它的形成、演化有着极为深刻的影响。本文利用X射线衍射分析(XRD)、扫描电子显微分析(SEM)等现代测试分析方法,对临夏盆地中新世沉积物的粘土矿物学特征进行了深入的研究。XRD结果表明,沉积物的矿物成分主要由石英、绿泥石、伊利石、方解石、斜长石、正长石、高岭石和和少量的坡缕石组成;中新世上层沉积物中见少量石膏和铁白云石;方解石的含量在各层中存在变化并且在泥岩中相对集中。SEM结果表明,绿泥石、伊利石可见转化形成坡缕石的现象,根据沉积物中粘土矿物的矿物学特征及其含量变化特征,临夏盆地中新世的气候演变总体上以干旱为主,个别期间则为温暖或寒冷少雨。更多还原

【Abstract】 Linxia basin is a late Cenozoic fault-block basin along the border between the Tibet plateau and the Loess plateau in Northwestern China.Its formation and sediments’ record may be directly affected by the structural dynamics and the uplift of the Tibet Plateau.For this reason,we studied the mineral characteristics of the Maogou formation of Miocene sediments using X-ray diffraction(XRD) and scanning electron microscopy(SEM).The XRD results showed that quartz,chlorite,illite,calcite,plagioclase,orthoclase, kaolinite,and trace palygorskite are present throughout the sequence of the cross-section in Linxia basin.In contrast,gypsum and ankerite occur occasionally in the upper portion of the Miocene deposits.The content of calcite varied with layers in the profile and was relatively concentrated in mudstone.Chlorite and illite were observed transforming into palygorskite under SEM observation.Based on the mineral characteristics and the change of mineral composition,especially the clay minerals,it could be inferred that an arid environment prevailed in the region with warm and cold intervals during Miocene time.更多还原