天山东段中天山隆起带冷却历史的研究

THE COOLING HISTORY OF THE MIDDLE TIANSHAN UPLIFT ZONE, EAST SECTION OF THE TIANSHAN RANGE,NORTHWEST CHINA

The Middle Tianshan uplift zone of the Tianshan folding system is located between the south and north Tianshan Hercynian eugocsyncline folding belts. Hornblende,muscovite, biotite .and microcline sampled from. the precambrian metamorphic rocks in the east section of the Middle Tianshan zone gave widely different K-Ar ages, whose validity is justified by the fact that individual mineral ages are consistently within an error of less than 10 percent with respective to that inherent in the determination procedure. Theis difference is thought to be a reflection of the cooling history of the Middle Tianshan. In accordance with the closure temperature values of Harrison, a cooling history of the Middle Tianshan was plotted and an approximate cooling rate of 1--2℃/my estimated. By using geothermal data of geosynclines, a curve of uplift rate and an average uplift rate of ca. 0.09 mm/yr, have been established for the Middle Tianshan. The uplift processes of this region were closely related to the subsidence and reasesndence of the north and south Tianshan. Based on K-Ar dating,their cooling history is estimated to be about 200 my, which is a very slow cooling process as compared with other areas ia the world.

The Middle Tianshan uplift zone of the Tianshan folding system is located between the south and north Tianshan Hercynian eugeosyncline folding belts. Hornblende, museovite, biotite and microcline sampled from the precambrian metamorphic rocks in the east section of the Middle Tianshan zone gave widely different K-Ar ages, whose validity is justified by the fact that individual mineral ages are consistently within an error of less than 10 percent with respective to that inherent in the determination procedure. Theis difference is thought to be a reflection of the cooling history of the Middle Tianshan. In accordance with the closure temperature values of Harrison, a cooling history of the Middle Tianshan was plotted and an approximate cooling rate of 1-2℃/my estimated. By using geothermal data of geosynclines, a curve of uplift rate and an average uplift rate of ca. 0.09 mm/yr. have been established for the Middle Tianshan. The uplift processes of this region were closely related to the subsidence and reaseendence of the north and south Tianshan. Based on K-Ar dating, their cooling history is estimated to be about 200 my, which is a very slow cooling process as compared with other areas in the world.