前寒武系对东秦岭-大别山钼成矿带成钼作用的贡献

对东秦岭-大别山钼成矿带25个钼矿床成矿母岩外接触带的地层及围岩观察统计,可清楚表明,所有钼矿床的赋矿层位均为前寒武纪老地层。成矿母岩侵入寒武系及以后地层中均形不成工业矿床。前寒武系不同的围岩岩性对钼矿床成矿作用的影响也不尽相同。主要反映在:1.地幔分异熔浆上侵时易于捕获前寒武系有用组分钼,而成其主要矿源层;2.成矿母岩的围岩岩性对矿床主要矿种组合有重要制约作用;3.围岩的物理力学性质,尤其是围岩的抗压抗剪强度(即岩石的破裂程度)对钼矿富集起关键作用。围岩容矿裂隙的发育程度决定了矿石的品位,从而控制着矿床的规模。东秦岭-大别山钼成矿带进一步寻找钼矿资源应以前寒武系(尤其是元古代老地层)作为找矿首选区域,特别是元古界岩石组合中的火山岩系列、大理岩及片岩系列构成的成矿有利围岩的地区。

The Contribution of Pre-Cambrian System to the Molybdenum Forming Action in East Qinling-Dabie Mountain Mineralization Belt

Statistical data of the stratum and the ore-forming mother rock and wall rock of 25 molybdenum deposits in east Qinling-Dabie mountain mineralization belt indicate that all the molybdenum deposits stratum are old stratum of pre-Cambrian System clearly,none is exception.When the ore-forming mother rockbody intrude in Cambrian system and later stratums,they are all not forming the industry mineral deposit.However,in the pre-Cambrian System stratum,the different country rock,carry on different influence of the ore-forming process.The main reflection is: 1)The pre-Cambrian System bed is the main source bed,it is easy catching the useful element of molybdenum when the magmatic melt intrude into the stratum during the mantle differentiation;2)As country rock of the ore-forming mother rock,its lithology takes latent restrict action to main commodity combination of the ore bed;3)The physics mechanics property of the country rock,particularly its compressive and shear strength,that is the broken degree of rock takes key action to molybdenum-forming.The development degree of contain ore cracks in the country rock decides grade of ore and thus limit the scope of mineral deposit.The predominant thought of looking for the molybdenum mineral resources in East Qinling-Dabie mountain molybdenum mineralization belt,the pre-Cambria System,especially in Proteroic stratum is the first to choose,and then volcanic rock series,marble and the schist series which constitute the beneficial country rock,is also the very important geological factor.