辽河断陷火山岩地质年龄及地层时代

THE AGE OF THE VOCANIC ROCKS AND THEIR GEOLOGICAL TIME IN LIAOHE DEPRESSION

以钾氩法、快中子活化法为主要手段,通过对58块样品的测定,建立了辽河断陷下第三纪火山岩喷发年代时间剖面,对下第三系9条组段界线年龄进行了修正。提出了本区古新统与始新统界线在房身泡组上下段之间,始新统与渐新统界线在沙河街组二段上亚段与沙河街组三段之间。同时还以古生物组合为基础,建立了与柴达木盆地、济阳坳陷古地磁测定结果之间的对比关系。

The main subject of this paper is to revise the geological time according to the results of vocanic rock age determination. The authors used K-Ar method as a major measure and isochronal line treatment, fast neutron activation method and geological test as complimenta-ry means to ensure the reliability of the results of determination. Tertiary vocanic rock eruptive time profile has been established for the first time, based on the determinations of 63 samples. After a composite induction, the ages of 9 of the ten boundaries in the Palaeogene have been revised. and a tertiary time profile is established. The authors propose, for the first time, that the boundary between Palaeocene and Eocene is at the interface between lower and upper members of Fangshen pao Formation, the boundary between Eocene and Oligocene is located at the interface between upper submember of the 2nd member of Shahe jie Fomation and 3rd member of Shahejie Fomation. In addition, the authors take the fossil assemblages as a dominant faor and the results of their examination as the complimentary one in a correla-tion of the palaeomagnetic data from this depression,Chaidamu Basin and Jiyang depression. The three far-separated depressions, located at different tectonic units, have the similar re-sults, using different methods. This shows that the studv is successful.