Characteristics And Genesis Of Cishan Pyroxene Diorite In Tongling Anhui Province

Cishan gold mine is a representative mine of the large copper-gold district inTongling. Its genesis is closely related to Cishan pyroxene diorite intrusions and it isrepresentative and typical in Tongling ore district gold deposits. The writer sees theintrusions as the focus of study. We could have a detailed investigation and researchto pyroxene diorite in Cishan gold mine.Microscope petrographic observation and mineralogical analysis shows thatCishan gold mine composed of plagioclase, pyroxene, hornblende and minor feldspar. For further study of the deposite, we could know pyroxene is mainly diopside, hornbl-ende is magnesium hornblende and biotite is magnesium biotite.The use of a pressure gauge to calculate the conditions of amphibole crystalliza-tion of amphibole. By calculation, the time is655MPa~841MPa and emplacementdepth is21.64~27.77km.The crystallization pressure of biotite is43MPa~65MPa, thetemperature is750～790℃and emplacement depth is1.45~2.15km. The result showsthat zircon crystallizes in deep magma crystallization then gets into the shallowmagma chamber by magma.Through geochemical analysis to pyroxene diorite, The result shows that Cishangold mine belongs to high potassium calc alkaline series to shoshonite series, its pare-nt magma from enriched mantle and lower crust.All the results shows that Cishan pyroxene diorite may experience the followingprocedure: magma formes in the deep magma chamber, part of underplating bas-alticmagma intrusion occurs, then intrusion of magma gets into sedimentary cover andform pyroxene pyroxene diorite.