| The Lannigou Carlin-type gold ore deposit is a very large gold deposit. Becauseof its enrichment in gold has drawn more attention to geologists, who have gone thereto execute scientific research attaining great achievements. This paper studies thegeochemical features and its genesis of the typical deposit on the basis of previousresearches. The study includes regional geological background, geological features,ore-controlling factors, geochemical characteristics of the deposit and deposit genesis.The main achievements as followed:1. The main ore-bearing strata of the deposits in the Bianyang Group of MiddleTriassic, then at the top of Xuman group. The main host rocks are of sandysedimentary rock (fine sandstone).2. Lannigou gold deposit is broken-bound gold deposit, whose tectonic zone ischaracterized by Huang Jiaping anticline and fragmentation development. The mainstructural line was north-northeast trending, followed by the North West. The highfault development make a great influence on body shape, the occurrence and size. Theore body is mainly characterized by bedded, lenticular, followed by vein and irregular.The occurrence of the ore body is in line with occurrence and strike in the mining area.Tectonic deformation strongly or superimposed fault fracture belt leads to theprecipitation of gold enrichment, with high grade. The ore structure is euhedral,subhedral granular, zoning, poikilitic, berry grain structure and granular structure. Thestructures are characterized by disseminations, veinlets, banded and brecciated.3. The wall-rock alteration is developmental, mainly contains silicification,pyrite and arsenopyrite. In pyritization development zone and fractured zone, the goldcontent is high. The results, observing thin section by electron probe show thataccretion crystal structure formed in pyrite and arsenopyrite, with high gold content.4. The study on geochemical characteristics, the main trace elements, REE andisotopic shows that the metallogenic materials of Lannigou gold deposits, for examplegold, fluids and mineralizer all come from the deep rock, not the surrounding rock.5. Au in the thermal fluid mainly transformed in the form of the gold-sulfurcomplex, followed by gold-silicon complex and gold–chlorine comples.6. The precipitation, enrichment and mineralization of gold are mainly resultfrom when the ore-forming fluids into favorable metallogenic environment, as the changing of T, P, pH, Eh, o2, s2reduction leading to mineralization and goldcomplex analytic leads to gold enrichment, finally to gold ore deposit. |
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