岩石矿物学杂志2012，Vol.31Issue(3)：432-440,9.
青藏高原东北缘早渐新世—早中新世干旱化的粘土矿物学证据——以兰州盆地为例
Clay mineralogical evidence of Early Oligocene-Early Miocene aridification on the northeast margin of the Tibetan Plateau: a case study of Lanzhou Basin
摘要
Abstract
To reveal palaeoclimatic evolution and aridification events of Early Oligocene-Early Miocene period on the northeast margin of Tibetan Plateau, the authors investigated micro-morphology, relative content of clay minerals and V(I11 + Chl)/V(Sme) ratios of sediments in Lanzhou Basin by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The relative content of clay minerals shows that the sediments are composed of illite, smectite, chlorite and minor illite-smectite mixed-layer clay (I11/Sme), indicating that aridification prevailed in Lanzhou in that period, with intervals of relatively warm and humid climate conditions. According to relative content and V(I11 + Chl)/I11(Sme) ratios, the palaeoclimate evolution in Lanzhou could be divided into four stages, i.e., (ⅠI ) relatively warm and dry and slightly humid period (31.5～28.8 Ma), ( Ⅱ) relatively cold and dry period (28.8～26.2 Ma), (Ⅲ) relatively warm and humid period (26.2～22.1 Ma), and (Ⅳ) relatively warm and dry and slightly humid period (22.1～16.5 Ma). SEM results indicate that clay minerals were apparently corroded in the relatively warm and humid period and presented distinctly physical weathering characteristics in the relatively arid period. The aridification events probably resulted from the multi-stage uplifts of the Tibetan Plateau.关键词
兰州盆地/早渐新世—早中新世/粘土矿物/干旱化/微观形貌Key words
Lanzhou Basin/ Early Oligocene-Early Miocene/ clay minerals/ aridification/ micro-morphology分类
天文与地球科学引用本文复制引用
梁国军,洪汉烈,殷科,李荣彪,王朝文,张克信,王锦荣..青藏高原东北缘早渐新世—早中新世干旱化的粘土矿物学证据——以兰州盆地为例[J].岩石矿物学杂志,2012,31(3):432-440,9.基金项目
青藏高原新近纪隆升过程与地质事件群研究(1212011121261) （1212011121261）
国家自然科学基金资助项目(41072030,40872038) （41072030,40872038）
