DISCOVERY OF CROSSITE AND PHENGITE ON THE NORTHERN MARGIN OF THE CENTRAL TIANSHAN MOUNTAINS AND ITS GEOLOGICAL SIGNIFICANCE
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摘要: 新疆中天山北缘存在一条早古生代构造混杂岩带。在该带东段乌斯特沟和干沟混杂岩中，发现了蓝闪石类矿物和多硅白云母。经电子探针分析，蓝闪石类矿物为青铝闪石，形成时压力为６７×１０５ｋＰａ。测得多硅白云母的ｂ０值为９０４１Ａ，晶体结构式中的离子数Ｓｉ平均为３４３。这些高压矿物的发现为确定中天山北缘构造混杂岩带的变质相提供了确凿的证据，从而为研究天山造山带的构造演化和古板块的活动史提供了必要的基础资料Abstract: There exists an Early Paleozoic tectonic mélange zone on the northern margin of the Central Tianshan Mountains.The authors first found glaucophanic amphiboles and phengite in mélanges at Wusitegou and Gangou in the eastern sector of the zone.Electron microprobe analysis shows that the glaucophanic amphiboles are represented by crossite formed at a pressure of 6.7×10 5 kPa.The b0 value of the phengite is 9.041 and the ion number Si in its crystal structure averages 3.43.The discovery of theses high pressure minerals provides reliable evidence for the metamorphic facies of the tectonic mélange zone on the northern margin of the Central Tianshan Mountains,thus furnishing necessary information for the tectonic evolution and paleo plate motion of the Tianshan orogenic belt.
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Key words:
- crossite /
- phengite geological significance /
- Central Tianshan Mountains /
- Xinjiang
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