Structural Alteration Mineral Mapping And Analysis Of Metallogenic Evolution In Nannihu Orefield, Western Henan

The Nannihu orefield is china’s largest molybdenum mine in monoblock explorationarea, Western Henan, belonging to the porphyry-skarn molybdenum deposits.Ore-controlling structure in the region need to be strengthened. The altered rocks is stillnot viewed as ageological survey unit, which is associated with mineralization. Thesetwo issues are difficulty in deep peripheral prospecting. I select“Structural AlterationMineral Mapping and Analysis of Metallogenic Evolution in Nannihu Orefield,WesternHenan” as my dissertation, The topic has important scientific significance and referencevalue in prospecting areas.I followed the tutor involved in four projects, such as “Orefield Tectonic Facies andMetallogenic Series of Studies in Precious Metals, Non-ferrous Metal Deposit GatheringHeNan Area, Southern Margin of The North China Ancient Land”. By studying relatedliterature, measuring nine altered rock sections which are about6.59km and structure. Icompleted the master’s thesis. The main progress as follows:(1) By measuring sections and studying microscopic rock mineralogy, I put contactmetamorphism of Nannihu rock into thermal contact metamorphism and hydrothermalmetamorphism. According temperature standard type minerals thermal contactmetamorphism is subdivided into wollastonite hornfels zone, garnet hornfels zone andcarbonate hornfels zone. According the degree of alteration hydrothermal metamorphismis divided into skarn zone, skarn alteration zone and weak skarn alteration zone.(2) Based on nine altered rock sections I establish structural alteration zonationlegend and map1:10000Nannihu orefield structural alteration mineral.(3) Mapping result reveal the distribution of altered rocks. Thermal contactmetamorphic belt develop extensive in Nannihu-Sandaozhuang mine. Hydrothermalalteration metamorphic belt focus on Sandaozhuang mine, becaused Country rock is carbonate rock. Hydrothermal alteration metamorphic belt was distributed NWW andNNE, which is obviously controlled by NWW fold and the mineralizing gepochstructures. Thermal contact metamorphic belt and shangfanggou altered rock belt mainlydistributed around the rock, which is obviously controlled by the rock.(4) Based on measuring orefield structure and staging studies, I restore the basicstructural framework. Plastic flow folds, whose rock compression capacity is0.52-0.65;NWW fold and squeeze fracture form earlier than the mineralization. Thetectonic stress field before mineralization squeezed nearly SN(σ1direction:4°).NNE-NE trending faults and activated NWW fracture are the mineralizing gepochstructures. The tectonic stress field of Mineralization squeezed NE-SW(σ1direction:228°). NE-NEE trending faults are constructions after mineralization. The tectonic stressfield after mineralization squeezed NNW-SSE(σ1direction:337°).