| 滇西兰坪盆地古近系构造—沉积演化与成矿关系 |
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| 引用本文： | 朱志军,郭福生,宋玉财,安倩.滇西兰坪盆地古近系构造—沉积演化与成矿关系[J].沉积学报,2014,32(6):997-1006. |
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| 作者姓名： | 朱志军 郭福生 宋玉财 安倩 |
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| 作者单位： | 1.东华理工大学省部共建核资源与环境国家重点实验室培育基地 南昌 330013; |
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| 基金项目： | 国家自然科学基金项目(批准号:U0933605)与国家自然科学基金项目(批准号:41362008)联合资助 |
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| 摘 要： | 兰坪中新生代盆地因堆积了巨量金属而倍受关注,盆地内沉积岩容矿贱金属矿床矿体的就位与印—亚大陆碰撞挤压和扬子古陆与滇藏古陆拼接碰撞而引起的盆地内部及周缘变形密切相关.古近纪充填序列特征及物质聚集分布规律显示,盆地总体上处于挤压构造背景下,其构造—沉积演化可划分为古新世—早始新世挤压拗陷和晚始新世—渐新世挤压走滑两个阶段.盆地演化过程中形成的控矿构造有挤压—拗陷—褶皱构造和区域大规模挤压走滑断裂构造,这些构造变形可以是容矿构造,也可以是导矿构造.古近世中期碰撞挤压拗陷阶段(55~41 Ma),形成了兰坪盆地西部拗陷褶皱推覆带内的脉状Cu矿床和富隆厂等脉状Cu-Ag-Pb-Zn矿床(48~49 Ma);晚期挤压走滑阶段(40~26 Ma)形成兰坪盆地东部逆冲推覆带内河西—三山Pb-Zn(-Ag-Sr)矿床和金顶超大型Pb-Zn矿(-34 Ma).兰坪盆地成矿与盆地构造—沉积演化显示出很好的耦合关系.
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| 关 键 词： | 构造—沉积演化 成矿 古近系 兰坪盆地 |
| 收稿时间： | 2013-08-22 |
The Relationship between Paleogene Tectonic-sedimentary Evolution and Mineralization of Lanping Basin in the Western Yunnan |
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| Institution: | 1.State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China Institute of Technology, Nanchang 330013;2.College of Geosciences, East China Institute of Technology, Nanchang 330013;3.Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037 |
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| Abstract: | The Mesozoic and Cenozoic basin of Lanping attracts more and more attention because of its accumulation of large amounts of metal deposits. This paper take Paleogene infilling sequence in the basin as the research object, adopt clastic composition, geochemical means to study the evolution of Lanping Paleogene basin, to further explore the relationship between Paleogene each evolution stage and mineralization in Lanping Basin, for the next step prospecting direction. The results show that Lanping Basin occur deformation due to the slow uplift of the Yangtze continent in Paleocene- Early Eocene(E1-E21), thus formed nearly north and south trending long and narrow type extrusion depression basin, on the whole the basin formed East steep and west slope, shallow in the east and deep in the west, sediment grain size coarsening upward gradually, showed the water upward shallowing and lake gradually atrophy.Because of the stage of the extrusion depression, it's relatively stable. Lanping Basin both east and west sides of orogenic belt to the basin hinterland strong thrust propagation because of the Himalayan movement in Late Eocene- Oligocene(E22-E3), formed pattern of the wedge nappe and sedimentary basin to further narrow, most areas of extrusion fold and with some degree of difference uplift, caused only residual sedimentary record intermontane basin in the north of Lanping Basin, the southern and central part of basin is mostly uplift and develop into denudation area. Most area of Lanping Basin inversion mountain, only in the nappe front residual intermontane basin, basin filling by molasse conglomerate of Baoxiangsi Formation and Jinsichang Formation in the Eocene-Oligocene, this period is Lanping Basin bidirectional thrust nappe most intensely active period. On the results of previous studies on the Lanping Basin metallogenic rule discovery that ore-forming and tectonic-sedimentary evolution of Lanping Basin with good coupled. Basin sedimentary rocks-hosted base metal deposit ore emplacement is closely related to the internal deformation of the basin, which controlled by Indian - Asian continental collision and extrusion, Yangtze paleocontinent and Yunnan-Tibet ancient mosaic and collision. According to the basin Paleogene infilling sequence characteristics and substance accumulation rules, thinking that the Paleogene Lanping Basin under the compressional tectonic background, forming the ore-control structures are extruded and depression - fold structure, mass region extrusion strike-slip structure. These structural deformation can be ore structures, can also be a guide ore structure. The Paleogene tectonic and sedimentary evolution of the Lanping Basin can be further divided into two stages: The first stage is squeeze-depression of the Paleocene - early Eocene, the second stage is the extrusion strike-slip stage of late Eocene-Oligocene.In the early stage of the extrusion and depression(65~41 Ma), formed vein Cu deposit and Fulongchang vein Cu-Ag-Pb-Zn (48~49 Ma) deposit of the Lanping Basin western depression fold nappe belt. Ore was only intermittent veinlike due to the space constraints of ore. In the late extrusion strike-slip stage (40~26 Ma), the edge of the basin to the side basin hinterland produce nappe movement and one side along the boundary fault strike slip movement. Formed large-scale east and west nappe. When the nappe advance to the deposition of gypsum salt built, gravity pressure and density inversion makes salt diapir rise form the dome structure, Thus formed Hexi-Sanshan Pb-Zn (-Ag-Sr) deposits and Jinding super large Pb-Zn (-34 Ma) deposits of the Lanping Basin Eastern thrust nappe belt. |
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