Research on the zoning and distribution of ore-bearing tectono-deformation-lithofacies belt in the Weilasituo Li-Sn polymetallic deposit, Inner Mongolia

The Weilasito Li-Sn polymetallic deposit has been discovered in Hexigten Banner, Inner Mongolia. The deep part of the deposit consists of greisen and amazonite altered quartz porphyry type ore with Sn, Zn, Rb, Nb and Ta. The middle part is composed of cryptoexplosive breccia cylinder type ore (mineralized spot) with Li and associated metallogenic elements such as Sn and Mo. The shallow part has the hydrothermal vein-type Sn, W, Zn, Cu, Mo and Ag ore. The polymetallic mineralization is controlled both by fractures and magmatic hydrothermal alteration. The measured profile of the mineralized fault alteration belt shows that the alteration zone is symmetrically distributed on both sides of the fault. From the fault center, silicification, greisenization, fluoritization and carbonatization are developed in sequence, thereby determining the alteration zones: ①The inner part is a silicified alteration facies zone with a width of 2~5 m. The orebodies and the surrounding rocks have been silicified. The light-colored minerals increase, the dark-colored minerals decrease, the rock becomes harder and more brittle, and small quartz veins are locally visible; ②The middle part is a greisenization altered facies zone, with a width of 5~10 m. The greisenization zone is developed outside the silicified zone, and larger mica granules are generally developed at the contact part of the orebody and surrounding rocks, other parts of the mica are of fine-grained types and consist of such rocks as lepidolite, muscovite, phlogopite and sericite; ③The outer part is a fluoritization-carbonatization altered facies zone, generally with the width of 20~30 m, and the larger one can reach more than 100m; the fluoritization-carbonatization alteration zone is far away from the orebody, and most of them fill the fissures of the surrounding rocks in the form of veins or films. Sometimes it is not easy to distinguish and divide them due to the superposition of other mineralization alterations. Through the study of the three-dimensional characteristics of ore-bearing tectono-deformation-lithofacies zone, a typical ore-prospecting model is established to provide geological basis for the exploration in this region.