| Illite Crystallinity Mapping of Very Low Grade Metamorphism of Triassic Metapelites in the Zoigê Area, Western China |
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| 作者姓名： | TANG Yan SANG Longkang YUAN Yanming YU Jishun ZHANG Yunpeng QI Xianmao and YANG Yunlong |
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| 作者单位： | 1 Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China;2 College of Earth Science and Resources, Chang’an University, Xi’an 710054, China;3 State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences,Wuhan 430074, China;4 Xi’an Center of Geological Survey, China Geological Survey, Xi’an 710054, China; 5Chengdu Institute of Geology and Mineral Resources, Chengdu 610082, China; 6 Sinopec Exploration Southern Company, Chengdu 610082, China |
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| 基金项目： | The authors are thankful to SINOPEC Exploration Southern Company, part of the National Oil and Gas Special Project XQ-04 and the Special Fund for Basic Scientific Research of Central Colleges, Chang’an University (CHD2011JC185) for supporting this study. Roger Mason revised the English of the first draft between acceptance and publication. |
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| 摘 要： | X-ray diffraction methods for estimating the metamorphic grade of diagenetic, anchizone and epizone in metapelites are reviewed and applied to samples from a 7000?m+ borehole in western China and surface samples from the surrounding Zoigê area. Kübler’s illite crystallinity (IC) measurements provide more consistent results than calculated values of percentage of illite in the I/S mixed layers and percentage of I/S mixed layers. Down-borehole IC values display a typical burial metamorphic relationship between stratigraphic level and IC. A method for preparing very low grade metamorphic maps is described, and isograds plotted on a regional geological map at selected values of IC, delineating a high temperature diagenetic zone, an anchizone, and an epizone. The map shows that IC values are controlled by stratigraphic level in the north of the study area (i.e. burial metamorphism), and proximity to an igneous intrusive body in the south (i.e. contact metamorphism).
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| 关 键 词： | X-ray diffraction metapelitic zone illite crystallinity percentage of illite in I/S mixed layers percentage of I/S mixed layers the metamorphic map |
| 收稿时间： | 4/5/2010 12:00:00 AM |
| 修稿时间： | 2011/5/20 0:00:00 |
Illite Crystallinity Mapping of Very Low Grade Metamorphism of Triassic Metapelites in the Zoigê Area,Western China |
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| Authors: | TANG Yan SANG Longkang YUAN Yanming YU Jishun ZHANG Yunpeng QI Xianmao YANG Yunlong |
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| Institution: | 1. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China;2. College of Earth Science and Resources, Chang'an University, Xi'an 710054, China;3. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;4. Xi'an Center of Geological Survey, China Geological Survey, Xi'an 710054, China;5. Chengdu Institute of Geology and Mineral Resources, Chengdu 610082, China;6. Sinopec Exploration Southern Company, Chengdu 610082, China |
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| Abstract: | X‐ray diffraction methods for estimating the metamorphic grade of diagenetic, anchizone and epizone in metapelites are reviewed and applied to samples from a 7000 m+ borehole in western China and surface samples from the surrounding Zoigê area. Kübler's illite crystallinity (IC) measurements provide more consistent results than calculated values of percentage of illite in the I/S mixed layers and percentage of I/S mixed layers. Down‐borehole IC values display a typical burial metamorphic relationship between stratigraphic level and IC. A method for preparing very low grade metamorphic maps is described, and isograds plotted on a regional geological map at selected values of IC, delineating a high temperature diagenetic zone, an anchizone, and an epizone. The map shows that IC values are controlled by stratigraphic level in the north of the study area (i.e. burial metamorphism), and proximity to an igneous intrusive body in the south (i.e. contact metamorphism). |
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| Keywords: | X‐ray diffraction metapelitic zone illite crystallinity percentage of illite in I/S mixed layers percentage of I/S mixed layers the metamorphic map |
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