宁夏卫宁北山地区铁矿区域成矿规律探讨
Discussion on the Regional Mineralization Law of Iron Ore in the North Mountain of Weining Area, Ningxia
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摘要: 宁夏卫宁北山地区地处河西走廊Fe-Mn-萤石-盐类-凹凸棒石-石油成矿带东段,是宁夏自治区最重要的金属矿产成矿远景区之一,这里分布有铁、铜、金等重要金属矿产。长期以来,关于该地区的铁矿成矿规律研究分歧很大,笔者从典型矿床和区域两个方面,对该地区的铁矿成矿规律进行探讨,提出关于该地区铁矿包括成因类型在内的区域成矿规律的基本认识。研究认为,卫宁北山地区铁矿成矿作用主要发生于石炭—二叠纪,早期表现为沉积成矿特征,后期不同程度经过构造-热液活动的叠加改造;地层、岩性和岩相是该地区铁矿成矿的主要控矿因素,地质构造虽然对成矿具有一定的积极意义,但是成矿作用主体还是沉积成矿;该地区的铁矿找矿方向应以沉积型菱铁矿为主,其次是沉积型菱铁矿层与构造(断裂)叠加改造所形成的沉积改造型赤-褐铁矿。Abstract: Weining North Mountain area lies in the east of Hexi Corridor Fe-MoFluorite-SaltAttapulgite-petroleum metallogenic belt,where is one of the most important perspective regions of the mineralization of metallic minerals in Ningxia,having many significant metallic minerals such as gold,sliver,and copper.For a long time,the understanding about iron ore mineralization in the area are much different.We discuss the regional mineralization law of iron ore in the area from the way of typical deposit and the regional deposit,obtaining a primary conclusion about the regional mineralizing law of iron ore including genetic type.We also believe that the iron ore mineralization of Weining north mountain area mainly occurred in CarboniferousPermian,which is characterized by the sedimentary mineralization in the early stage and by the tectonic-hydrothermal activities in the late;the stratum and lithofacies and lithology are the main control factors of iron ore mineralization and the geologic structure's function is minor because major mineralization is deposition,though it plays a certain positive role in mineralization;the exploration direction of iron deposits in the area should focus on the deposition's siderite first,and then hematite-limonite which is formed by superimposition transformation of deposition siderite seam and tectonic(faults).