The Petrological And Metallogenic Study Of The Tectonic Altered Rock Belt Of The Wall-rock In Sandaozhuang Mo-W Deposit, Luanchuan

Luanchuan Sandaozhuang porphyry-skarn deposit is the largest molybdenum andtungsten mine in China, and in-depth and extensive geological studies have beenmade, but with the increasing difficulty in prospecting in the deep and peripheral areaof the ore field, the theoretical method of geological prediction of mineralizationneeds to be innovated. According to the rock structure and combining with weakstudies on altered rock, the author selected The petrological and metallogenic study ofthe Tectonic Altered Rock Belt of the wall-rock in Sandaozhuang Mo-W deposit,Luanchuan as the thesis title, which has important theoretical significance andprospecting value.The author is responsible for the petrologic study of Henan exploration fundproject Studies of Lithofacies and Mineralization of Ore field Structure of PreciousMetals and Nonferrous Metals Deposit Gathering Area in Henan Province at SouthEdge of Ancient Land of North China. The author, on the basis of five4.5km-longgeological cross sections carried out a systematic petrologic study, established themineral assemblage rule, and took this as the legend to prepare MineralizationDiagram of Structural Alteration Lithofacies of Nannihu Ore Field. At the same timethe author combined with tectonic evolution and magmatism and explored theregularity of mineralization of Sandaozhuang deposit. Taking Sandaozhuangmolybdenum and tungsten deposit as the model, this thesis achieved results andprogress as follows:1) By means of geological cross section study, the thesis divided altered rocksinto thermal contact metamorphic rock and hydrothermal metasomatism altered rock.Thermal contact metamorphic rock contains three zones: contact quartzite zone,biotite halleflinta zone and diopside halleflinta zone; hydrothermal metasomatismaltered rock contains two zones: skarn zone and skarn calcium silicate hornfels zone.2) The thesis systematically proposed field marks of the above five alterationzones, which contain field characteristics such as occurrence, structure, constitution and color of rocks.3) The thesis determined the typical minerals and mineral content of thestructural alteration zone: a. contact quartzite zone: quartz,≥85%, or quartz andfeldspar10%-15%; b. biotite halleflinta zone: quartz (40%-60%), feldspar (15%-30%)and biotite (10%-20%); c. diopside halleflinta zone: quartz and feldspar (30%-70%),diopside (10%-40%) and hornblende (5%-20%), etc.; d. skarn zone: calcium andaluminum-andradite (about70%or20%-40%) and diopside (20%-50%); e. skarncalcium silicate hornfels zone: wollastonite (≥30%), calcite, diopside, and andradite.4) Based on the above field and laboratory data, the thesis established the legendsystem of alteration zone and prepared the mineralization diagram of lithofacies.5) The mineralization process contains two stages. The first is post-magmatichydrothermal stage. At the upper section of Sanchuan Fm, calcium silicate hornfels-calcium silicate marble in metasomatism formed skarn, in which dye-likemolybdenite was formed; the second is medium and low temperature hydrothermalstage. Hornfels zone and skarn zone with hydrothermal metasomatism encounteredpotassic alteration, silicification and carbonation, in which potassic alteration andsilicification are the main mineralization phases. Molybdenum mineralizationconcentrated in skarn and skarn calcium silicate hornfels. The mineralization model ofstructural alteration of Nannihu Ore Field was set up on the basis of mineralizationmechanism analysis of rock, structure, alteration, mineralization physics andchemistry.