| Pyroxene is a kind of common rock-forming mineral,whose crystal structure and geochemical characteristics have typical mineral typomorphic significance for skarn deposits.In this paper,the changes of pyroxene mineral composition in different types of skarn deposits are reviewed and their indications for mineralization are analyzed.The mineralogical and mineral geochemical characteristics of pyroxene in the typical skarn deposits in the eastern part of North China-the Hanxing Iron Mine and the Luanchuan Molybdenum Mine are studied in detail,and the typomorphic characteristics of minerals are analyzed.Studies have shown that pyroxene plays an indicative role in skarn deposits:The content of the pyroxene in Fe,Cu,Au skarn deposits is high in diopside and lower in hedenbergite and johannsenite,and it is also rich in Mg;The content of hedenbergite and johannsenite and the higher ratio of Mn/Fe in Mo?Pb-Zn and W-Sn multimeta skarn deposits are important prospecting marks.The Pyroxene contains more Zn can be used as typomorphic mineral of Pb-Zn mineralization;The pyroxene in Au,Fe skarn deposits contains more Al2O3,while the content of Al2O3 is less in Pyroxene of Pb-Zn,Cu,W skarn deposits.The mineralogical characteristics and geochemical characteristics of pyroxene in the Hanxing iron deposit are consistent with the typical skarn iron deposits in China.According to the results of the EPMA,diopside-salite is the main component,and it often associated with andradite,indicating the metallogenic environment is high oxygen fugacity and low acidity.The endmember content of hedenbergite in the ore body decreases gradually from the inside to the outside,which indicates that Fe is mainly derived from magma,besides,the Mg-Fe of pyroxene is negatively correlated,and the formation of pyroxene ring is related to Fe and Mg.X-ray diffraction analysis shows that the pyroxene cell parameters a,b and V are positively correlated with Fe,but negatively correlated with A1?,meanwhile the decrease of a,b and V indicates the increases of the pressure of metallogenic environment.The results of EPMA of the pyroxene in Luanchuan molybdenum show that it mainly consists of salite-hedenbergite,and hedenbergite is associated with molybdenite.The content of Fe is higher in some pyroxene in the Sandaozhuang mining area is closely related to the hornfelsed development in this area.The SiO2-Al2O3 whole rock basicity discrimination diagram of the pyroxene shows that the magmatic rocks in this area are sub alkaline,moreover,the pyroxene in this area contains more Si and less Al. |
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