摘要
本文根据区域地层及同位素年代学等新资料,讨论了天山地区前寒武系研究中存在的几个争论问题.认为库鲁克塔格地区达格拉格布拉克群属上太古界而非下元古界;建议太古、元古为“宇(宙)”一级的地层(年代)单元,元古宙三分,即早元古代(1800—2500Ma)、中元古代(1000—1800Ma).晚元古代(800—1000Ma);震旦系两分,上部仍称为震旦系,下部称扬子系,二者以特端爱肯组冰碛岩之顶界为界(相当南沱冰碛岩之顶界时限为700Ma),上述两系均归属于显生宇(下古生界);波瓦姆群上亚群与杨吉布拉克群相当(时代为长城纪);广泛发育在中天山(天山中部)的变质岩(特别是变质较深的岩层)时代多为中元古代(长城纪、蓟县纪);库鲁克塔格、阿克苏一带的冰成岩成因较为复杂,有的与重力流伴生或为重力流所改造.
1. The Dakelakebulak complex ( Group ) is the oldest rockes ( Late Archaean) in Kuluktag region, its upperboundary is about 2500 Ma.
2. In Xinjiang the author has provisionally recommended to subdivide the pro-terozoic Eon. in to three units of Era rank, .the ,late proterozoic(Pt3),: 800-850-1000 Ma, the Middle Proterozoic ( Pt2) , 1000-1800 Ma and the Early, Proterozoic ( Pt1 ) , 1800-2500 Ma.
The Sinian system and The Yantze System belong to the Phanerozoic Eonothem (the Early Palacezoic) , with time boundary at 800-8500 Ma,700 Ma, 600 Ma.
3. Subdivision of the Precambrian Tianshan of Xinjiang (Kuluktag region) is expressed in the following table.
4. The Bowam Group is included in the Middle Proterozoic ( Changcheng System) and can be correlated with the Yangjibulak Group.
5. The Precambrian Metamorphic zone develops Well in the Central Tianshan, in Xingxingxia region (eastern part of Csntral Tianshan), Rb-Sr and U-Pb isotopic age data are 1400-1900 Ma,and in Ekendaban(western part of the Central Tianshan) U-Pb age is 1379 Ma. They belong to Middle Protarozoic(The Changcheng System).
6. The Glacial deposits Kuluktag and Aksu region are very complicated, and have been reformed locally by gravity flows.
出处
《新疆地质》
CAS
CSCD
1990年第1期80-90,共11页
Xinjiang Geology
