新疆北部前寒武系划分和对比

库鲁克塔格是新疆北部前寒武系分布较广,地层层序相对完整的地区.作者以库鲁克塔格为地层模型区,以同位素第龄为格架,初步确定了本区群级地层单元的界线及归属.在岩石地层、生物地层、化学地层等各种方法相互印证的基础上,建立并完善了前寒武纪的地层层序.

DIVITION AND CORRELATION OF PRECAMBRIAN SYSTEM IN NORTHERN XINJIANG

The Precambrian System in northern Xinjiang is mainly developed in the northern and northwestern margins ( Kurukiag and Aksu-Wushi region) of Tarim Basin, Tianshan and AItay mountains, among which Kuruktag region is regarded as a strato-type region since Precambrian System is widely distributed and rather complete in this region. Based on the isotopic datings the boundaries of the various groups of the Precambrian in Kuruktag are primarily determined. And according to the data of petrostratigraphic, biostratigraphic and chemical stratigraphic sequences, the integrated Precambrian sequence is established as follows. From lower to upper: Late Archean Dakelakebulak Group ( Complex ); Early Proterozoic Xinditag Group Middle Proterozoic ( Changchen System ) Bovamu Group or Yangjibulak Formation and ( Jixian System ) Airjigan Group; Late Proterozoic ( Qinbaikou System ) Pargontag Group and ( Sinian System ) Kuruktag Group. The isotopic age ( 2500 Ma ) reported for the first time by single Zircon Pb-Pb method confirms the existence of Upper ( Late ) Archen. The isotopic ages of -1800Ma and 1 000Ma, obtained from Rb-Sr and K-Ar dating, represent the boundary ages of Early Proterozoic with Middle proterozoic and of Middle Proterozoic with Late Proterozoic, and the ages of 1400Ma and 800-850Ma represent the important boundary ages of division of Middle and Upper Proterozoic. Therefore the 2500Ma, 1800Ma , 1000Ma , 800-850Ma are the important geologic event ages of Precambrian crust evolution in this area. Finally, the authors give a plan of division and correlation of Precambrian System in northern Xinjiang.