青藏东缘六合—香多镁铁质深源包体的平衡 P-T条件及其指示意义

doi:10.11867/j.issn.1001-8166.2004.05.0722

地球科学进展 ›› 2004, Vol. 19 ›› Issue (5): 722 -731. doi: 10.11867/j.issn.1001-8166.2004.05.0722

所属专题：青藏高原研究——青藏科考虚拟专刊；

青藏东缘六合—香多镁铁质深源包体的平衡 P-T条件及其指示意义

魏启荣 ^1,2;王江海 ²

中国地质大学材料科学与化学工程学院，湖北武汉 430074；中国科学院广州地球化学研究所，广东广州 510640

收稿日期:2003-06-05 修回日期:2003-10-17 出版日期:2004-12-20
通讯作者: 魏启荣（1964-），男，湖北蒲圻人，副教授，主要从事火山岩岩石学、地球化学和无机材料研究. E-mail:E-mail：weiqr1030@cug.edu.cn
基金资助:
国家重点基础研究发展规划项目“大陆碰撞过程中壳幔物质能量交换及冈底斯带成矿背景评估”（编号：G1998040807）；中国博士后科学基金项目“三江中段扬子与冈瓦纳陆块间地球化学边界的研究”资助

EQUILIBRIUM P-T CONDITIONS OF MAFIC DEEP-DERIVED ENCLAVES AND ITS SIGNIFICANCE IN LIUHE-XIANGDUO AREA OF EASTERN TIBET

WEI Qi-rong ^1,2, WANG Jiang-hai ²

1.College of Materials Science & Chemical Engineering, China University of Geosciences,Wuhan 430074, China; 2. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China

Received:2003-06-05 Revised:2003-10-17 Online:2004-12-20 Published:2004-10-01

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依据青藏东缘六合-香多镁铁质深源包体中石榴石、辉石、角闪石和斜长石的矿物电子探针成分，采用GrtCpx温度计（T EG79、T P85、T K88、和 T R2000）、GrtHbl温度计（T GP84和 T RV2000）和HblPl温度计（T BH90）以及角闪石Al压力计（P AlinHb l）估算了包体的平衡温压条件。结果表明，石榴透辉岩、石榴斜长角闪岩、石榴角闪岩、斜长角闪岩和角闪石岩包体的平衡温压分别是770～920℃和 0．83～1．50GPa（相当于27～50km深）、730～950℃和 0．85～1．04GPa（相当于28～34km深）、 720～900℃和 0．74～1．32GPa（相当于24～44km深）、512～753℃和 0．71～0．98GPa（相当于23～32km深）以及 0．60～0．84GPa（相当于20～28km深）。前 3类包体主要来自下地壳，平衡温压较高（720～950℃、0．74～1．50GPa）；后 2类包体主要来自中地壳，平衡温压较低（510～735℃、0．60～0．98GPa）。包体的平衡温压条件还暗示了高钾岩浆起源的最小深度在50km以上。

关键词: 六合-香多, 青藏东缘, 镁铁质深源包体, 平衡温压

Based on electron microprobe analyses of garnets, pyroxenes, amphiboles and plagioclases from mafic deep-derived enclaves in Liuhe-Xiangduo area, eastern Tibet, calculated equilibrium temperatures of the enclaves by Grt-Cpx geothermometers (T_EG79, T_P85,T_K88, and T_R2000), Grt-Hblgeothermometers (T_GP84and T_RV2000), and Hbl-Plgeothermometers (T_BH90), and equilibrium pressures by aluminum-in-amphibole geobarometrys (P_Al-in-Hbl). The results showed that equilibrium temperatureand pressureconditions of garnet diopsidite, garnet amphibolite, garnet hornblendite, amphiboliteand hornblenditewere 770~920 ℃ and 0.83~1.50 GPa (equivalent to27~50 km depth), 730~950 ℃ and 0.85~1.04 GPa (28~34 km), 720~900 ℃ and 0.74~1.32 GPa (24~44 km), 512~753 ℃ and 0.71~0.98 GPa (23~32 km), and 0.60~0.84 GPa (20~28 km). The P-T conditions in the enclaves revealed the former three types of enclaves came from low-crust with higher P-T (720~950 ℃ and 0.74~1.50 GPa), and the latter two derived from middle-crust with lower P-T ( 510~735 ℃ and 0.60~0.98 GPa). The P-Tconditionof enclaves still indicated the source depth of the high-K magma is 50km at least. 

Key words: Eastern Tibet, Liuhe-Xiangduo, Mafic deep-derived enclave, Equilibrium temperature and pressureconditions.

中图分类号:

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