Study On The Geologic Characters Of The Erlangping Group And The Relation To Copper Polymetalic Deposit Mineralization In East Qinling Orogenic Belt In The West Of Henan Province

Erlangping Group of Early Paleozoic is located in North Qinling Oroneic Belt. There are amount of copper polymetalic deposits in this volcanic-sedimentary rocks series. The deposits are mainly exist in Liushanyan, Huoshenmiao and Dalishu Formations of Erlangping Group.The theories of mineralization system, geochemistry, submarine hydrothermal fluids eruption deposit lithogenesis and mineralization were used to study the characters of geology and typical deposits of Erlangping Group in East Qinling Orogenic Belt and the raltion between them was dicussed in the thesis.Through the studying of stratigraphy and sedimentary formation of Erlangping Group and regional geology , it is consided that the structural-stratigraphic framework of the Erlangping Group was set up by the ductile thrusting shear deformation in middle and deep layer which was resulted from the subduction in two directions of the Erlangping back-arc basin and the collisions orogeny. The structural-stratigraphic framework at the west of Nanyang Basin is a anticline which axis extended from Lujiaman to Sikeshu, but at the east of Nanyang Basin The structural-stratigraphic framework exists as a "synformal anticline".Based on the analysis of the geochemistry characters of the basic volcanic and cherts and the stratigraphic association and sedimentary characters of Erlangping Group, it is considered that the volcanic-sedimentary association of Erlangping Group was formed in the back-arc basin in Early Paleozoic. The scale of the back-arc basin of Erlangping is large at the east of Nanyang basin and its deposit environment was like a pelagic basin. The scale of the back-arc basin was small at the west of Nanyang Basin, and the sedimentary environment had characters of continental margin. The Ce_anom of chert shows that sedimentary environment is transition environment of redox.. The volcanic rocks of Erlangping Group at the east of Nanyang basin are mainly MORB type, but at the west they are mainly island arc calc-alkline volcanic suit.Through the study of geochemistry features of strata and the sources of magma, it is found that Erlangping Group at the east of Nanyang Basin was rich in copper and poor in lead and zinc, but at the west of Nanyang Basin it was poor in copper and rich in lead and zinc.Research of the characters of typical deposits and correlative rock series shows that mineralizing matter was provided by both the basic lava and felsic igneous rocks. On the basis of study on the lithological geochemical characters, it is consided that cherts and skarns were formed by hydrothermal sedimentation . The hydrothermal liquids was low temperature (<200°C) which was formed by the combine of magmatic hydrothermal fluids and seawater, but baritic was deposited by the hydrothermal liquids of high temperature (>200°C) .Through the synthetically analyses on regional geology and typical deposits of the region, the volcanic-sedimentary association of Erlangping Group was formed in the back-arc basin and produced deposit of Cu> P^ Zn ^ Fe polymetalic mineralization of VMS type. Bases on the differences of minerals , mineralizing tectonic environment , sources of mineralizing substance and ore characteristics, the types of the deposit ore of the study area can be devided into three types: Cu-Zn type ,Pb-Zn and Fe-Cu type deposit.