| 柴北缘都兰高压麻粒岩的变质演化及形成的动力学背景 |
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| 引用本文： | 于胜尧,张建新,李金平.柴北缘都兰高压麻粒岩的变质演化及形成的动力学背景[J].岩石学报,2009,25(9):2224-2234. |
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| 作者姓名： | 于胜尧 张建新 李金平 |
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| 作者单位： | 中国地质科学院地质研究所,北京,100037 |
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| 基金项目： | 国家自然科学基金项目，中国地质科学院地质研究所所长基金，中国地质调查局地质调查项目 |
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| 摘 要： | 在柴北缘-阿尔金HP/UHP变质带东端,新识别出一个高压麻粒岩单元.高压基性麻粒岩是高压麻粒岩单元的主体,还包括少量高压中酸性麻粒岩.高压基性麻粒岩主要由平衡共生的石榴子石、单斜辉石、斜长石组成,还含有不等量的蓝晶石、角闪石、石英、金红石、黝帘石/斜黝帘石、钛铁矿、方柱石等矿物.高压长英质麻粒岩主要包括石榴子石、蓝晶石、钾长石、斜长石、石英等矿物,并具有少量的单斜辉石和角闪石.岩石学和矿物学数据显示高压麻粒岩经历了多阶段的变质演化,温压计算获得峰期高压麻粒岩相的变质条件为1.40～1.85GPa和800～925℃.退变质高角闪岩相的变质条件为P=0.80～1.05GPa和T=580～695℃：进一步的退变质作用发生在低角闪岩相/绿片岩相条件下(<0.8GPa和<550℃).岩石学、矿物学及年代学资料研究表明都兰地区的高压麻粒岩具有与相邻榴辉岩不同的变质演化历史,而不是榴辉岩在抬升过程中热松弛作用所致.高压麻粒岩可能形成于与陆壳俯冲相关的造山带增厚的陆壳根部环境,形成的深度为50～70km.
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| 关 键 词： | 柴北缘 都兰 高压麻粒岩 大陆俯冲 |
| 收稿时间： | 2/2/2009 12:00:00 AM |
| 修稿时间： | 2009/3/21 0:00:00 |
Metamorphism history and dynamics of high-pressure granulites in the Dulan area of the North Qaidam Mountains, northwest China |
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| YU ShengYao,ZHANG JianXin and LI JinPing.Metamorphism history and dynamics of high-pressure granulites in the Dulan area of the North Qaidam Mountains, northwest China[J].Acta Petrologica Sinica,2009,25(9):2224-2234. |
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| Authors: | YU ShengYao ZHANG JianXin and LI JinPing |
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| Institution: | Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China |
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| Abstract: | A high-pressure granulite unit was recognized in the Dulan area, the eastern end of the North Qaidam-South Altyn HP-UHP metamorphism belt, Northwest China. High-pressure granulites are mainly mafic in composition although small amounts of acid-intermediate varieties also exist. Mineral assemblages in equilibrium in mafic granulites contain mainly garnet, clinopyroxene, plagioclase, with different amounts of kyanite, amphibole, rutile, quartz, zoisite/clinozoisite, scapolite and ilmenite, whereas acid-intermediate granulites contain garnet, kyanite, K-feldspar, plagioclase and quartz, with small amounts of clinopyroxene and amphibole. Petrologic and mineralogical data indicate these HP rocks experienced multistage metamorphism history. Thermobarometry of the peak mineral assemblages yields P-T conditions of 1.40 ～ 1. 85GPa and 800 ～ 925℃ . Retrogression began under high amphibolite-facies conditions estimated at 0. 8 ～ 1. 05GPa and 580 ～ 695℃ , and is followed by subsequent retrogression under low amphibolite-facies/greenschist-facies conditions ( <0. 8GPa and < 550℃ ). This study suggests that the Dulan high-pressure granulites experienced a single metamorphic history, and not associated with the effects of thermal relaxation after eclogite-facies metamorphism recorded in adjacent eclogites. The high-pressure granulites probably formed at the bottom of thickening continental crust related to continental subduction corresponding to the depth of about 50 ～ 70 km. |
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| Keywords: | North Qaidam Mountains Dulan High-pressure granulite Continental subduction |
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