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引用本文:秦旭平,李德威,刘建雄,毛晨. 粤东南燕山期热隆伸展及其古水热系统——以恩平-新丰拆离断层为例[J]. 中国地质, 2018, 45(6): 1188-1204.
QIN Xuping,LI Dewei,LIU Jianxiong,MAO Chen. Yanshanian thermo-upwelling extension and palaeo-hydrothermal system in southeast Guangdong: A case study of Enping-Xinfeng detachment fault[J]. Geology in China, 2018, 45(6): 1188-1204(in Chinese with English abstract).
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粤东南燕山期热隆伸展及其古水热系统——以恩平-新丰拆离断层为例
秦旭平1,2, 李德威1, 刘建雄3, 毛晨4
1.中国地质大学地球科学学院, 湖北 武汉 430074;2.中国有色桂林矿产地质研究院有限公司, 广西 桂林 541000;3.广东省佛山地质局, 广东 佛山 528000;4.中国地质大学资源学院, 湖北 武汉 430074
摘要:
粤东南地区广泛发育燕山期NE-SW走向的拆离断层系统。文章对恩平-新丰拆离断层进行了野外地质调查和室内测试分析,重点研究了拆离断层之下韧性剪切带中的糜棱岩和拆离断层上盘与高角度脆性正断层伴生的硅化岩。初步认为,研究区热隆伸展构造于燕山早期开始形成,糜棱岩的变形温度在350℃左右,硅化岩内石英中气液包裹体的均一温度在155℃~326℃,盐度在2.74%~21.61% NaCleqv,平均盐度为11.17% NaCleqv,古热液流体沸腾时的温度在235℃~241℃,激光拉曼光谱分析结果表明,含硅热液的成分为富含Si、CO2的NaCl-H2O溶液。硅化岩流体包裹体的H-O稳定同位素组成表明古水热流体为岩浆水与大气降水混合作用的产物。沿着正断层分布的硅化岩可能是燕山期古水热型地热能的重要标志。燕山期热隆伸展构造系统及其深层与浅层相结合的古水热系统对认识现代地热能的类型、成因及其分布规律有一定的意义。
关键词:  热隆伸展  拆离断层  韧性剪切带  流体包裹体  硅化岩  古水热系统
DOI:10.12029/gc20180609
分类号:P542+.31
基金项目:中国地质调查局项目"1:5万区域地质调查"(1212011121246,1212011220400)、珠江三角洲及周边地区控热地质构造调查研究和国家自然科学基金(41172188)联合资助。
Yanshanian thermo-upwelling extension and palaeo-hydrothermal system in southeast Guangdong: A case study of Enping-Xinfeng detachment fault
QIN Xuping1,2, LI Dewei1, LIU Jianxiong3, MAO Chen4
1.Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, Hubei, China;2.China Nonferrous Metals(Guilin) Geology and Mining Co,. Ltd, Guilin 541000, Guangxi, China;3.Foshan Geological Bureau of Guangdong Province, Foshan 528000, Guangdong, China;4.Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, Hubei, China
Abstract:
NE-SW trending Yanshanian detachment faults are widely spread in southeast Guangdong. The authors carried out geological survey and physical and chemical test of Enping-Xinfeng detachment fault, with emphasis placed on the mylonite in the ductile shear zone below this detachment fault and the silicified rocks related to the high angle normal fault on the hanging wall of the detachment fault. The authors believe that the initiation age of the upwelling-extension structure was in early Yanshanian, the deformation temperatures of the mylonite which had the kinematic property of ductile rheology in the ductile shear zone were about 350℃, and the mylonite was brought onto the surface during later tectonic uplift. The microthermometric study of the fluid inclusions in the silicified rocks indicates that the homogeneous temperatures of the fluid inclusions are between 155℃ and 326℃. The salinities are between 2.74% and 21.61% NaCleqv, with an average of 11.17% NaCleqv, the temperatures of the silicon-contained hot liquid are about 241℃, and the silicon-contained hot liquid is believed to be NaCl-H2O solution with rich silicon and carbon dioxide according to Laser-Raman microspectroscopy. Compositions of H-O stable isotope imply that the paleo-hydrothermal fluids were derived from the mixing of magmatic water and rain water in the study area. The silicified rocks distributed along the strike of the normal fault possibly are the significant indications of the paleo-hydrothermal system in Yanshanian. The thermo-upwelling extension system and the deep and shallow integrated palaeo-hydrothermal system in the late Yanshanian are significant for the understanding of the type, the mechanism and the distribution regularities of the modern geothermal system in southeast Guangdong.
Key words:  thermo-upwelling extension  detachment fault  ductile shear zone  fluid inclusions  silicified rock  paleo-hydrothermal system