Lawsonite-bearing eclogites in the north Qilian and north Altyn Tagh:Evidence for cold subduction of oceanic crust

被引：0

作者：

ZHANG Jianxin MENG Fancong Institute of Geology Chinese Academy of Geological Sciences Beijing China ^{[100037
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机构：

来源：

ChineseScienceBulletin | 2006年 / 10期

关键词：

north Qilian; north Altyn Tagh; lawsonite-bearing eclogite;

D O I：

暂无

中图分类号：

P588.125 [];

学科分类号：

070901 ;

摘要：

Lawsonite-bearing eclogites are recog-nized respectively in the north Qilian (NQL) and north Altyn Tagh (NAT), based on petrography and mineral chemistry. Lawsonite coexists with omphacite and phengite as inclusions in garnet, indicating ec-logite-facies metamorphism. Peak metamorphic con-ditions for equilibrium lawsonite-omphacite-phengite- garnet peak assemblages are estimated to be 2.1―2.4 GPa and 420―500℃, which is in the stability field of lawsonite eclogite-facies. A low geotherm of 6―8℃/km is referred, which is in consistent with a cold subduction. The occurrences of lawsonite-bearing eclogites in both NQL and NAT provide further evi-dence that the NAT HP/LT metamorphic belt is pos-sibly the northwestward extension of the NQL HP/LT metamorphic belt offset by the Altyn Tagh left-lateral slip fault. The NQL and NAT lawsonite-bearing ec-logites are formed by subduction of oceanic crust before collision of the Alashan and Qilian blocks in early Paleozoic.

引用

页码：1238 / 1244

页数：7

共 3 条

[1]

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[2]

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[3]

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