滇南马鞍底钪钒钛磁铁矿床地质特征及找矿预测

Geology and ore prediction of the Maandi V-Ti magnetite deposit in southern Yunnan Province

马鞍底铁矿床位于点苍山—哀牢山变质基底杂岩南段。矿区主要出露小羊街岩组(Pt1xy)、中—晚二叠世镁铁质岩石(νP2-3),可见中—晚三叠世(T2-3)的逆断层和中型规模的向形构造。矿区圈定的4个矿体均呈似层状产出,产于中—晚二叠世镁铁质岩石(νP2-3)中,顶板、底板、夹石均为镁铁质岩石,镁铁质岩石为成矿母岩和赋矿岩石。矿石具粒柱状变晶结构、交代结构,稀疏—稠密浸染状构造。金属矿物主要为钒钛磁铁矿,主要有益组分为Fe,伴生有益组分为Ti、V、Sc。矿床成因类型为晚期岩浆结晶分异型。经估算矿床中铁、钛、钒的资源量达中型规模,钪矿达超大型规模。建议今后工作中应注意寻找哀牢山岩群(Pt1A)分布区中的钪钒钛磁铁矿床,同时注意评价伴生的钪。

The Maandi iron deposit is located in the southern section of Diancang mountain-Ailao mountain basement metamorphic complex(Pt) of Proterozoic age. At the local scale, Xiaoyangjie rock formation(Pt1xy) of early Proterozoic age and mafic rock(νP2-3) of Middle-Late Permian age exposed, and reverse faults of Middle-Late Triassic age(T2-3) and medium scale synform structures can be seen. All four ore bodies delineated at the deposit area occurred as stratiform zones within the middle-late Permian mafic rock(νP2-3), with hanging walls and bottom walls and internal waste zones consisting of mafic rock.The mafic rock is parental rock and host rock. Ore has granular-prismatic crystalloblastic texture, replacement texture and sparsely to densely disseminated structure.The metal mineral is dominated by V-Timagnetite.The main beneficial component is Fe, associated with other beneficial components of Ti, V, Sc. The deposit type is regarded as a late magmatic segregation deposit. The estimated mineral resources of iron, titanium and vanadium reach medium sizes respectively, and that of scandium reach a super large size. In the future work, attention must be paid to exploring for Sc-V-Ti magnetite deposits in the Middle-Late Permian mafic rock(νP2-3) within Ailaoshan rock group and assessing associated Sc resources.