陕西勉县后沟-大坪山锰矿床地质-地球化学特征及控矿因素

近年里在南秦岭磷.锰成矿带中-东段的后沟-大坪山一带发现3条锰-磷矿化带，并圈定出3个锰矿体.锰矿体均赋存于下寒武统塔南坡组碳泥质岩-碳酸盐岩内，属海相沉积变质+改造类型锰矿床.本文在初步总结该区锰矿成矿地质特征的基础上，对优质锰矿成矿条件和成矿控制作用进行了系统深入的探讨.研究表明：本区锰成矿元素沉积受扬子地台北缘具有准稳定性质的前震旦纪基底裂陷构造盆地的控制，具有磷-锰共存、低Co、低Co/Ni比以及相对较高富集系数的Ni、Pb、Zn和B等成矿地球化学特征，成矿物质具有多源性，主要与扬子地块前震旦纪基底的陆源风化迁移沉积有关.锰成矿作用具有明显的盆控性、层控性和岩性专属性.优质锰受磷、锰分离沉积控制，层位上具有下磷上锰分层成矿特点.基于上述研究，本文提出含锰灰岩（白云质灰岩）和含黄铁矿碳质千枚岩为本区锰矿找矿标志.

Metallogenic geologic-geochemical conditions and metallogenic controlling factors of the Hougou-Dapingshan Mn-Ore Deposit in Mianxian,Shaanxi province

Hougou-Dapingshan area in southern Shaanxi,where occurred three manganese(Mn)phosphorus (P) metallogenic belts including three high quality Mn ore deposites discovered recently,located in the middle-eastern segment of the South Qinling Mn-P Metallogenic Zone.The Mn-bearing rock series were carbonaceous argillaceous and carbonate rocks of the Lower Cambrain Tananpo Formation,and the Mn deposit should be a marine sedimentary type reconstrutted by metamorphism.Based on analyses of Mn metallogenic geological characteristics,the metallogenic conditions and metallogenic controlling process of the Mn ore deposits were discussed.It should be emphasized that the sedimentation of Mn ore-forming elements was controlled by the faulted depressing tectonic basin on a transitional crust consisted of the Pre-Sinian metamorphic basement rocks,the metallogenic geochemistry background was Mn-P concomitance,lower Co content, lower Co/Ni ratio and Ni-Pb-Zn-B of higher enrichment coefficient, and the metallogenic substance was polygenous.The Mn metallogenic process had an evident feature of basin-controlling,stratabound,and lithologic specialization.The high quality Mn ore deposits were controlled by separated Mn and P sedimentation, with a texture of upper Mn seam and lower P seam.The manganic limestone(including dolomitic limestone)and pyritic charry schist were considered as prospecting indications in the area.