南非Postmasburg锰矿田堆积型锰矿体地质特征及找矿方向

Geological Characteristics and Prospecting Direction of Detrital Manganese Ore-body in Postmasburg Manganese Ore Field,South Africa

南非Postmasburg锰矿田内发育了大面积的堆积型锰矿体,其形成与沉积-受变质型原生锰矿体有关。区内矿体分布广泛、厚度不均、形态各异,按堆积矿发育的部位,可将矿体划分为山脊斜坡型、斜坡边缘型和山前平地型等3类。矿石主要矿物成分以方铁锰矿、褐锰矿和硬锰矿为主。Fe、Mn含量负相关性较强,总体含量稳定,与古元古代的沉积环境及Fe、Mn胶体的沉积性质密切相关。结合区内地质勘探资料,对区内堆积型锰矿地质特征、矿床成因以及找矿方向进行了探讨,认为区内矿石来源于原生锰矿体,成矿后期的构造运动破坏了原生矿体的完整性和连续性,白云岩溶蚀构造是矿石赋存的主要空间,山脊斜坡边缘为地形强切割地段,是寻找堆积矿的优选部位。

Extensive detrital manganese ore-body is developed in Postmasburg manganese ore field, South Africa,which formation is related to the original metamorphosed sedimentary manganese ore-body. The ore-bodies are widely distributed and the thickness and shapes are difference with each other.Ac-cording to the development area of the detrital ore-bodies,the ore-bodies in Postmasburg manganese ore field can be divided into ridge slope type,slope borderline type and piedmont plain type ore-bodies.The main composition of minerals are bixbyite,braunite and psilomelane.Fe and Mn contents with a strong negative correlation,the overall contents of Fe and Mn is stable,which is closely related to the sedimen-tary environment in Paleoproterozoic era and the sedimentary natures of Fe and Mn colloid.Based on the geological prospecting exploration data of Postmasburg manganese ore field,the geological characteristics of the detrital manganese ore-bodies,mineral deposit genesis and prospecting direction are analyzed,the results show that the ores is derived from the original manganese ore-bodies,the integrality and continuity of original manganese ore-bodies are destroyed by the late metallogenic tectonic movement,dolomite cor-rosion structures is the main space of ores occurrence,ridge slope edge is the terrain strong cutting area, is the optimal prospecting regions of detrital manganese ore-bodies.