| 郯庐断裂带张八岭隆起南段肥东群石榴角闪岩变质P-T演化史对其构造属性的制约 |
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| 引用本文： | 石永红,朱光,王道轩.郯庐断裂带张八岭隆起南段肥东群石榴角闪岩变质P-T演化史对其构造属性的制约[J].岩石学报,2009,25(12):3335-3345. |
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| 作者姓名： | 石永红 朱光 王道轩 |
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| 作者单位： | 合肥工业大学资环学院,合肥,230009 |
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| 基金项目： | 国家自然科学基金项目 |
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| 摘 要： | 通过对张八岭隆起南端肥东群中磁铁石榴铁闪石岩的岩相学、矿物成分分析和热力学评价,并结合野外地质填图和共生围岩分析表明,该岩石经历了5期变质作用,展现了顺时针的P-T演化特征,早期阶段表现为近等压升温,晚期阶段为降温降压的过程,其峰期变质平均P-T条件为:524℃和0.49GPa.结合地质背景和郯庐断裂带的演化特征分析,早期过程可能反映的扬子基底所经历的区域变质过程,晚期过程可能是由于郯庐断裂的后期抬升分量所致,不具有造山带的P-T演化特征.对比前人对宿松群的变质演化历史的研究,肥东群和宿松群峰期变质压力差可达0.8GPa,表明两者属于不同变质级别的块体.因而,肥东群和宿松群不能作为被郯庐断裂左行错开的标志层.由此表明,张八岭隆起南段所出露的肥东群变质杂岩,属于扬子板块上的变质基底,郯庐断裂带活动中将其剥露地表,并没有经历过大别造山带的变质作用.
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| 关 键 词： | 肥东群 磁铁石榴铁闪石岩 黑云磁铁石榴角闪岩 P-T演化 |
Metamorphic P-T evolution for the garnet amphibolite from Feidong Group in the south of Zhangbaling uplift across Tan-Lu fault and its influence on tectonics |
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| SHI YongHong,ZHU Guang,WANG DaoXuan.Metamorphic P-T evolution for the garnet amphibolite from Feidong Group in the south of Zhangbaling uplift across Tan-Lu fault and its influence on tectonics[J].Acta Petrologica Sinica,2009,25(12):3335-3345. |
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| Authors: | SHI YongHong ZHU Guang WANG DaoXuan |
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| Abstract: | On the basis of the investigation from petrology, minerals chemistry analysis and thermodynamic appraise on the magnetite-garnet grunerites in the Feidong Group across the southern part of the Zhangbaling uplift belt, and combined with field geological mapping and the analysis of associated rocks, it is understood that the magnetite-garnet grunerites experienced five phases of metamorphism, and display a clockwise P-T path. The early metamorphic stage shows the process of increasing temperature at nearly iso-pressure, the late metamorphic stage has a decreasing temperature and pressure path, and the average peak P-T condition is 524℃ and 0.49GPa. According to the analysis from the geological background and the evolution of the Tan-Lu fault zone, the early stage reflects regional metamorphic progress, the late stage result from the uplifting related to motion of the Tan-Lu fault zone. Hence, this P-T path has no any characteristics of orogenic evolution. Compared with the metamorphic evolutions from early study, 0.8GPa gap in the peak pressure exists between Feidong and Susong groups, which implies the two units belong to different metamorphic terrain. Therefore, the discrepancy suggests that the two units should not be treated as a key, correlative terrain for sinistral motion of the Tan-Lu fault zone. It is suggested that metamorphic complexes of the Feidong Group exposed on the southern part of the Zhangbaling uplift belong to metamorphic basement of the Yangtze plateform. They were unroofed by the motion along the Tan-Lu fault zone and have not experienced orogenic metamorphism of the Dabie belt. |
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| Keywords: | Feidong Group Magnetite-garnet grunerites Biotite-magnetite-garnet amphibolite P-T evolution |
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