川滇黔菱形地块地球物理基本特征及其与内生成矿作用的关系
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摘要
扬子准地台西南缘是我国重要的成矿区带。通过该区区域地球物理资料 (包括重力测量、航空磁测、深反射地震和天然地震资料 )的分析整理和编图 ,发现在扬子地台西南缘存在着一个菱形块体———川滇黔菱形地块 ,由四条 (隐伏 )深断裂带所围限。地球物理资料较为清楚地反映了菱形地块的构造格架。西侧重力异常梯度陡变 ,地壳厚度急剧变厚 ;内部存在由地幔隆起形成的重力高异常带 ,隆起带可能是菱形地块在元古宙时期裂解留下的遗迹 ;沿边界断裂地震活动剧烈而频繁。菱形块体的边界断裂及其内部的隆起带控制着本区的成矿作用 ,不同时期的矿产在菱形地块内有规律地分布 ,沿近南北向地幔隆起带分布有元古代沉积 喷流型Fe Cu矿床 ,其两侧分布有与晚古生代峨眉山玄武岩有关的铜矿和密西西比型铅锌矿床 ;沿菱形块体边界分布有新生代与超壳深断裂有关的富碱斑岩型金 (多金属 )矿床 ,沿菱形地块内部的南北向深断裂 (如小江深断裂 )有剪切带型金矿床。不同类型的矿床有时相互叠加形成复合成因的矿床 (如东川地区 )。这表明 ,不同时期的构造背景控制着不同类型矿床 ,同时表明 ,扬子地台西南缘是一个不够稳定的地块 (准地台或活化了的地台 ) ,菱形地块陡变的地球物理特征明显不同于其东侧稳定块体 (缓变 )
The western rim of the Yangzi Paraplatform, is one of the most important metallogenic belts in the Southwest of China. By the result of data-processing and compiling of geophysics, including regional gravity survey, aeromagnetic survey, deep reflect imagine of seismic and natural seismic, it is discovered that there exists a rhombic block, Chuan-Dian-Qian Rhombic Block(Chuan, Dian and Qian is the short name of Sichuan, Yunnan and GuiZhou, respectively), which is surrounded by four faults in various directions. The information of geophysics reveals clearly the tectonic framework of the rhombic block. At the western of rhombic block, the gradient of gravity anomaly changes sharply, showing crust soundly thickening westwards, within the rhombic block there exists an positive gravity anomaly zone caused by mantle′s doming striking SN direction, which should be a relict of early stage (Proterozoic) rift inside rhombic block; along the boundary of the rhombic block seismic activities have frequently been taken place. The boundary faults of rhombic block, as well as the rise belt within the block, control the metallogeny in this region. Ore deposits, produced in varying geological time, are distributed regularly in the rhombic block: along the SN mantle rise zone of the rhombic block′s center, Proterozoic VMS-type Fe-Cu ore deposits; Cu deposits and MVT Pb-Zn deposits, related to Late Paleozoic (Permian) Emeishan basalt, are distributed in the two flanks; along the boundary faults of the rhombic block, porphyry Au deposits related to alkalic porphyries are occurred; along the deep faults inside the block(such as Xiaojing Deep Fault), shear zone-type Au deposits are produced. In some occasion, deposits with different types are superposed to form composite genesis deposits, such as in Dongchuan district. The result shows that the tectonic setting in different stage controls deposits of different types, at the same time, the west rim of Yangtze Paraplatform is not steady enough(rejuvenated at Paleozoic to Cenozoic), with sharply varying geophysic characteristics, different from the eastern of paraplatform.
The western rim of the Yangzi Paraplatform, is one of the most important metallogenic belts in the Southwest of China. By the result of data-processing and compiling of geophysics, including regional gravity survey, aeromagnetic survey, deep reflect imagine of seismic and natural seismic, it is discovered that there exists a rhombic block, Chuan-Dian-Qian Rhombic Block(Chuan, Dian and Qian is the short name of Sichuan, Yunnan and GuiZhou, respectively), which is surrounded by four faults in various directions. The information of geophysics reveals clearly the tectonic framework of the rhombic block. At the western of rhombic block, the gradient of gravity anomaly changes sharply, showing crust soundly thickening westwards, within the rhombic block there exists an positive gravity anomaly zone caused by mantle′s doming striking SN direction, which should be a relict of early stage (Proterozoic) rift inside rhombic block; along the boundary of the rhombic block seismic activities have frequently been taken place. The boundary faults of rhombic block, as well as the rise belt within the block, control the metallogeny in this region. Ore deposits, produced in varying geological time, are distributed regularly in the rhombic block: along the SN mantle rise zone of the rhombic block′s center, Proterozoic VMS-type Fe-Cu ore deposits; Cu deposits and MVT Pb-Zn deposits, related to Late Paleozoic (Permian) Emeishan basalt, are distributed in the two flanks; along the boundary faults of the rhombic block, porphyry Au deposits related to alkalic porphyries are occurred; along the deep faults inside the block(such as Xiaojing Deep Fault), shear zone-type Au deposits are produced. In some occasion, deposits with different types are superposed to form composite genesis deposits, such as in Dongchuan district. The result shows that the tectonic setting in different stage controls deposits of different types, at the same time, the west rim of Yangtze Paraplatform is not steady enough(rejuvenated at Paleozoic to Cenozoic), with sharply varying geophysic characteristics, different from the eastern of paraplatform.
引文
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曹显光,王兴彬.2001.云南莫霍面形态与大型矿床空间关系探讨[J].云南地质,20(1):73～80.
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阚荣举.1992.云南遮放至马龙地学断面[M ].北京:地震出版社.
卢德源等.1988.川滇南北向构造带北段丽江—西昌—新市镇地区的地壳深部结构[M].北京:地质出版社.
吕伯西,王增,张能德等.1993.三江地区花岗岩类及其成矿专属性[M ].北京:地质出版社.
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孙文珂等.1998.1∶500万中国及邻区海域重力系列编图及说明书[M ].北京:地质出版社.
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徐锡华,程国良,于贵华等.2003.川滇菱形块体顺时针转动的构造学与古地磁学证据.地震地质,25(1):61～70.
杨建民,薛春纪,徐珏,等.2001.滇西北喜马拉雅期富碱斑岩地质特征及其成矿作用[A].
陈毓川.喜马拉雅期内生成矿作用研究[C].北京:地质出版社.
曾普胜,莫宣学,喻学惠.2002.滇西富碱斑岩带的Nd,Sr,Pb同位素特征及其走滑挤压背景[J].岩石矿物学杂志,21(3):231～241.
曾普胜,杨伟光,喻学惠.1999.滇西富碱斑岩带及其与金矿化的关系[J].地球学报,20(增刊):367～372.
张连生,钟达赉,刘小汉.1991.金沙江缝合线与红河-哀牢山断裂的构造关系[A].见:中国科学院地质研究所岩石圈构造演化开放研究实验室年报(1989-1990)[C].北京:中国科学技术出版社.
张云湘,骆耀南,杨崇喜.1988.攀西裂谷[M].北京:地质出版社.
郑建中.1988.攀西裂谷带的地震活动和应力场的基本特征[M ].北京:地质出版社.
钟大赉,TapponnierP ,吴海威,等.1989.左行走滑断裂———碰撞后陆内变形的重要形式[J].科学通报,(7):526～529
④ 张翼飞.2003.云南东川昆阳群中含金剪切带型金矿简介[C].见:2003年10月14-15日成都,“峨眉地幔柱与资源环境效应学术研讨会”论文集摘要.83-85
② 四川物化探队.1989.四川省区域物化探资料综合研究报告.成都:四川地矿局测绘队制印.
③ 孙文珂等.1999.重点成矿区物化探遥感编图成果综合研究矿产预测成果报告.中国地调局内部制印.
曹显光,王兴彬.2001.云南莫霍面形态与大型矿床空间关系探讨[J].云南地质,20(1):73～80.
黄汲清,陈炳蔚.1987.中国及邻区特提斯海的演化[M ].北京:地质出版社.
阚荣举.1992.云南遮放至马龙地学断面[M ].北京:地震出版社.
卢德源等.1988.川滇南北向构造带北段丽江—西昌—新市镇地区的地壳深部结构[M].北京:地质出版社.
吕伯西,王增,张能德等.1993.三江地区花岗岩类及其成矿专属性[M ].北京:地质出版社.
任纪舜,姜春发,张正坤等.(黄汲清指导).1980.中国大地构造及其演化———1∶4000000中国大地构造图简要说明[M ].北京:科学出版社.
孙文珂等.1998.1∶500万中国及邻区海域重力系列编图及说明书[M ].北京:地质出版社.
光炽.1982.华南两个富碱侵入岩带的初步研究[A].中国科学院贵阳地球化学研究所年报[C].贵阳:贵州人民出版社.
吴根耀.2000.造山带地层学[M ].成都:四川科学技术出版社.
徐锡华,程国良,于贵华等.2003.川滇菱形块体顺时针转动的构造学与古地磁学证据.地震地质,25(1):61～70.
杨建民,薛春纪,徐珏,等.2001.滇西北喜马拉雅期富碱斑岩地质特征及其成矿作用[A].
陈毓川.喜马拉雅期内生成矿作用研究[C].北京:地质出版社.
曾普胜,莫宣学,喻学惠.2002.滇西富碱斑岩带的Nd,Sr,Pb同位素特征及其走滑挤压背景[J].岩石矿物学杂志,21(3):231～241.
曾普胜,杨伟光,喻学惠.1999.滇西富碱斑岩带及其与金矿化的关系[J].地球学报,20(增刊):367～372.
张连生,钟达赉,刘小汉.1991.金沙江缝合线与红河-哀牢山断裂的构造关系[A].见:中国科学院地质研究所岩石圈构造演化开放研究实验室年报(1989-1990)[C].北京:中国科学技术出版社.
张云湘,骆耀南,杨崇喜.1988.攀西裂谷[M].北京:地质出版社.
郑建中.1988.攀西裂谷带的地震活动和应力场的基本特征[M ].北京:地质出版社.
钟大赉,TapponnierP ,吴海威,等.1989.左行走滑断裂———碰撞后陆内变形的重要形式[J].科学通报,(7):526～529
④ 张翼飞.2003.云南东川昆阳群中含金剪切带型金矿简介[C].见:2003年10月14-15日成都,“峨眉地幔柱与资源环境效应学术研讨会”论文集摘要.83-85
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