Geological Features And Genesis Of Gold Deposits In Xiaoshan Area,Henan Province

The Xiaoshan area of Henan Province is located in the eastern part of the Qinling orogenic belt in the middle of the Huaxiong platform ridge-breaking ridge.It is part of the Xiaoqinling–Xiaoshan–Xionger Mountain–Waifang Mountain Au–Ag–Mu polymetallic metallogenic belt.It has good metallogenic geological conditions.It is an important metallogenic zone of the West Henan gold deposit.This paper analyzes the geological characteristics of the deposit and the geological characteristics of the mining area in the Shenjiayao gold deposit and the Bankuan gold deposit in the Xiaoshan area;It analyzes the physical and chemical conditions of mineralization by measuring the temperature of fluid inclusions in the area;By analyzing the characteristics of sulfur,lead and hydrogen and oxygen isotopes,the source of ore–forming materials is summarized.Get the following conclusions and understanding:1.Based on the wall rock alteration characteristics of the Bankuan gold mine area and the Shenjiayao gold mine area,it can be determined that the two alterations of silicification and pyrite sericite play a decisive role in the process of gold mineralization.2.The metallogenic temperature of gold deposits in the study area is mainly 243–270?,which is a hydrothermal deposit with medium temperature.3.The metallogenic pressure variation of the half-width No.9 vein inclusions ranges from243 to 347 MPa.It is calculated based on the overlying stratum 3 km deep and corresponding to1000 atmospheres.The metallogenic depth in this area is about 3.1 km,which belongs to shallow middle formation.4.The average change of salinity(wt%Na Cl)of the inclusions in the mining area is 8.02?11.90,mostly 6.86?11.22,and the overall content is not high,which is quite different from the salinity in the metamorphic rocks.The nature of the ore-forming fluid is not metamorphic heat The fluid should be a magma hydrothermal fluid mainly related to granite.5.The ore–forming fluid is rich in H₂O?CO₂?C1^–?SO₄^2–?Na⁺,and belongs to the H₂O–Na Cl and H₂O–Na Cl–CO₂systems.Early gold mineralization may migrate in the form of Au Cl^2–,Au Cl^4–,and later in the form of Au[HS]₂^–.The ore-forming solution is mainly magma water,mixed with atmospheric precipitation and some metamorphic water.