六盘山地区早白垩世磁性地层年代及其构造意义  

Early Cretaceous Magnetostratigraphy of Liupanshan Area and Its Tectonic Implications

作　　者：胡鸿飞[1,2,3] 戴霜[2] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]兰州大学资源环境学院西部环境教育部重点实验室,甘肃兰州730000 [3]武警黄金第二支队,内蒙古呼和浩特010010

出　　处：《现代地质》2013年第2期278-287,共10页Geoscience

基　　金：国家重点基础研究发展计划项目(2009CB421008);国家自然科学基金项目(41272127);国土资源部地质大调查项目(1212011220492)

摘　　要：研究六盘山白垩纪盆地演化对于认识中国大陆白垩纪及现今构造-环境格局形成具有重要意义。通过对六盘山地区火石寨剖面的沉积地层进行古地磁采样测量,初步获得六盘山群的磁性地层年代为100～130 Ma。综合古地磁测年结果、盆地沉积演化和构造事件分析,认为白垩纪六盘山盆地具拉张断陷性质,经历了早期拉张裂陷阶段(125.3～129.6 Ma)、中期扩张-稳定坳陷阶段(109.6～125.3 Ma)和晚期湖盆萎缩阶段(102.0～109.6 Ma)。盆地早期拉张裂陷和中期扩张坳陷阶段的时限与目前已确认的中国东部构造伸展转折的高峰期(110～140 Ma)相对应,是对中国东部岩石圈减薄作用和构造体制转变的响应。The research on the Cretaceous basin evolution of Liupanshan is crucial for understanding the formation of the Cretaceous and present China tectonic-environmental pattern. The paleomagnetie study of the Liupanshah Group in the Huoshizhai section in the central-northern Liupanshan basin yielded an age control on the Liupanshan Group at 110 -130 Ma. Combined with the regional tectonic data the magnetostratigraphic results depicted that the Liupanshan basin was a rift-related depression basin and had undergone the early extension stage spanning in the period of 125.3 - 129.6 Ma, the middle expansion and stable depression stage during 109.6 - 125.3 Ma and the late extinction stage during 102.0 - 109.6 Ma. The age of the early extension stage is good to match with the time constraint obtained by the most studies of main duration of the tectonic extension in the east of China continent, indicating that this stage is the respondenee to the lithospheric mantle detachment and geodynamic system transformation in the east of China continent.

关 键 词：磁性地层年代 早白垩世 六盘山群 构造意义 

分 类 号：P534.53[天文地球—古生物学与地层学]