Study On The Stratigraphic Characters Of The Luanchuan Group And The Relation To Pb-Zn Deposit Mineralization In The Southwest Of Henan Province

The area where the thesis deals with lies in southern margin of the North China platform , which is an important polymetallic mineralization belt in China, Proterozoic Era metamorphic strata widely distributed in the area. The most of magmatite exposed are procaledonian blastogabbro and granite-porphyry of Yanshan stage, main fault structures in the region extend north-west by west. According to analysis of sedimentary characters and geochemistry characters of Luanchuan Group of New Proterozoic Era. Luanchuan Group was formed in an ancient passive continental margin. its sedimentary assemblage is a series of terrigenous rock-carbonate rock of littoral facies or neritic facies. the strata generally contain abundant elements of Pb,Zn,Cu,Ag,Mo and W. As a result of study, recognized Sanchuan Formation and Meiyaogou Formation of the Luanchuan Group are the main source beds of the Pb-Zn deposits. Through the analysis of geology and geochemistry features of typical Pb-Zn ore deposits in the area, It is known that ore mainly occurred deposit arise in terrigenous rock of the first Member of the Sanchuan Formation and carbonate rock of the Meiyaogou Formation, ore bodies take on stratified or vein. Deposit geochemistry character: Pb isotope composition is stable, μ< 9.58 on an average . δ34S value is -1.2～10.9‰, most 3～7‰. Ore δ34S value is higher than granite-porphyry δ34S value 3‰, lower than Pyriteδ34S value 12‰in stratum. isotope value D of quartz and carbonate in Pb-Zn ore(δDV-SMOW‰) rang from –90‰to 52‰,δ18OV-SMOW‰rang from 6.2‰to 22.6‰. REE appear to negative anomaly ofδEu, light REE enrichment, ∑REE 0.6～41.3×10-6,LREE/HREE 1.5～16.5。microelement content of sphalerite and pyrite vary in a big range, the microelement character of different deposit is different. Fluid inclusion homogenization temperature of quartz and calcite vary in 110～340℃, salinity 3.71～12.28%. Based on above analysis, the Pb-Zn ore deposits in the area can be divided into two kinds, One is a magmatic ore deposit, which have something to do with granite-porphyry action of Yanshan stage, mineralizing matter mainly came from mantle and lower crustal . Another is sedimentary or stratabound ore deposit, mineralizing matter mainly came from stratum country rock..