Geological and Geophysical Model of Thrust Controlling on Iron Ore Deposits in the Southwestern Fujian Province
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摘要: 闽西南地区位于武夷山成矿带西南部, 自元古宙以来经历了多期次的构造演化, 推覆(滑脱)构造广泛发育, 并对区内"马坑式"铁多金属矿床具有控制作用.通过对推覆构造特征、主要赋矿岩层和推覆界面的研究发现, 闽西南地区主要的赋矿岩层为C2+3-P1q, 主要沿AnD/C1l及C1l/C2+3+P1q这2个界面发生推覆, 以上2个区域性的推覆构造面可以作为成矿热液的地球化学屏蔽层位.通过地表地质对深部赋矿岩层及推覆界面的分布和构造格局进行解析, 结合可控源音频大地电磁法(CSAMT)进行的深部探测剖面解译, 建立了闽西南推覆构造控矿的地质-地球物理模型, 该模型在一定程度上可为该地区深部矿产预测提供依据.Abstract: The southwestern Fujian is located in southwestern Wuyishan mineralization zone, where nappe (slippage) structures extensively developed after a multi-stage tectonic evolution since the Proterozoic, with control over "Ma Keng"-small, medium and large iron polymetallic deposits in the region. It is found in this study on nappe structures associated with ore-bearing rocks and nappe interfaces that the ore-bearing strata mainly consist of C2+3-P1q; the nappe mainly occurred along the AnD/C1l and C1l/C2+3+P1q interfaces; and these two regional nappe structures may be the geochemical shield of the hydrothermal ore-forming fluid. A ore-controlling geological-geophysical model of the nappe structure in southwestern Fujian is established by surface geological analysis of distribution and tectonic framework of the deep ore-bearing rock and nappe interface combining the interpretation of deep controlled source audio magnetotelluric method (CSAMT), which will certainly facilitate deep prospecting.
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图 1 闽西南地区推覆构造与铁矿床分布(据张达等,2011修改)
1.前泥盆纪侵入岩;2.海西-印支期侵入岩;3.燕山期侵入岩;4.基底岩系;5.盖层岩系;6.燕山期火山岩系;7.主干断层;8.大中小型铁矿床及矿化点;9.推覆构造带及编号;10.可控源音频大地电磁测深区
Fig. 1. Distribution of nappe structures and iron ore deposits in the southwestern Fujian Province
图 2 龙岩九峰崎推覆构造剖面图(a)、王庄煤矿井田剖面图(b)和新寮-中甲构造剖面图(c)(图 2a据黄锦华,1992修改;图 2b据王桂梁,1992修改)
上寒武统;O1w.下奥陶统魏坊组;D3.上泥盆统;C1l.下石炭统林地组;P1t.下二叠统童子岩组;P2cp.上二叠统翠屏山组;T3w.上三叠统文宾山组
Fig. 2. The cross-section of Jiufengqi nappe structure (a), the drilling cross-section of Wangzhuang (b) and the structure profile of Xinliao-Zhongjia (c) in Longyan area
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