昆仑山口羌塘组磁性地层与新构造运动

STUDY ON THE MAGNETIC STRATIGRAPHY OF THE QIANGTANG FORMATION AND THE NEOTECTONISM

格尔木昆仑山口羌塘组厚５９６ｍ，磁性地层年代为２．９０—０．６５ＭａＢＰ，不整合在羌塘组上的望昆冰碛层年龄约为０．６５—０．６ＭａＢＰ，其下惊仙冰期年龄约为３．０ＭａＢＰ。羌塘组中新发现的三趾马化石年龄为２．０８ＭａＢＰ，三趾马生存高度为海拔１０００—２０００ｍ，古纬度为３２．５６°，计算出东昆仑地区第四纪以来上升速率为２．３—３．１ｍｍ／ａ，向北水平移动速率１４３ｍｍ／ａ，西大滩左行走滑断层滑动速率为１０ｍｍ／ａ。

The Qiangtang Formation,at the pass of the Kunluns,596m in thichness,having a magnetic stratigraphy age of about 2.90-0.65Ma B.P.,is overlain unconformably by the morianes of the Wangkun Glacial stage about 0.65-0.60Ma B.P.and underlain by the outwash gravel of the Jingxian Glacial Stage about 3.00Ma B.P.in age.The Hipparion sp newly discovered in the Qiangtang Formation was determined to be of 2.08Ma age.Since the habitat of the Hipparion sp is about at a height of 1000-2000m above sea level,at a latitude of about 32.56°,it is estimated that the East Kunlun Mountains region might have undergone an uplifting at a rate of about 2.3-3.1mm/a and a Northward horizontal movement of about 143 mm/a since Quaternary.Meanwhile,the Xidatan sinistral slip fault in the East Kunlun Mountains has a slip rate of 10mm/a.