摘要
本文对柴达木各主要成盐盆地中8个深孔的古地磁测试数据进行了整理解释,其结果与古地磁极性年表可以对比。其中除布容正极性带未能确定亚带外,在松山负极性带中,哈拉米洛、奥尔都维、留尼旺亚带均全部出现.并在 B/M 界限之下、哈拉米洛亚带之上还出现一个正极性亚带,其年代接近0.8Ma,相当于上桂亚带;在高斯正极性带中,出现凯纳和马莫斯亚带;在吉尔伯特负极性带中显示了科奇蒂、努尼瓦克、西杜夫和斯瓦拉亚带。结合孢粉资料,Q/N 气侯界面与古地磁 M/G 界面大致吻合,据平均沉积速率推算,年代为2.508—2.564Ma。结合第四纪地层的岩性岩相变化,首次确定了青藏高原中的两次新构造运动强烈抬升期,其年代分别为2.80—2.00Ma,1.60—1.10Ma,并认为差异升降是造成柴达木西北部与东南部沉积速率变化规律相反的原因。
The Palaeomagnetic data of eight deep boreholes in main salt-forming basin of Qaidamhaye been arranged and explained in this paper,and the result has been got that the magnetostrati-graphic sequence can be Compared to the palaeomagnetic polarity chronology.Several subzones existgenerally in each polarity zone except Brumhes normal polerity zone.In Matsuyana reversed polarityzone,there are Jaramillo,Olduvai and Reunion subzone,and,furthermore,there occurs another nor-mal polarity subzone under the B/M boundary,above Jaramillo subzone,similarly,in Gauss normalpolarity zone,there are Kaena and Mammoth subzones,in Gilbert reverse polarity zone,there areCositti,Nunivak,Sidufiall and Thvera subzone.Combining with sporopollen data and the inference of average sedimentation rate, the Q/N climateinterface and the M/G palaeomagnetic interfaceare almost coincident,being at the age of 2.508Ma—2.564Ma.According to the lithofacies and lithoiogic change of Quaternary System,two inten-sive upliftstages of neotectonic movement of Qingnai-Tibet plateau first have been put forward in this paper,their ages being at 2.80—2.00 Ma and 1.60—1.10Ma respectively,further the differential uplift anddepression have been considered as reason causing the opposite change rule of sedimentation rate in thenorthwest part and the southeast part of Qaidam.
关键词
第四纪
地层
磁性
柴达木盆地
Qaidam basin Magnetic stratigraphy Q/N interface Neotectonic movement Differential uplift and depression Sedimentation rate
