| The family of garnet minerals are widely distributed in nature,especially as typical minerals in skarn ore deposits,which can be found in different types of ore-bearing skarns.Their chemical composition,physical properties and spectroscopy have obvious typomorphic significance.So they can become a kind of important trace minerals.This article is based on the detailedly studies on garnets in the Hanxing Iron Mine and the SanDaozhuang Molybdenum in the eastern part of North China,systematically summarizes the typomorphic characteristics of garnets in different skarn-type deposits,and the indicator of garnets on the mineralization and metallogenic environment are analyzed.Garnet in different skarn-type deposits has different end-member composition.The content of garnet in Fe,Cu,Au,Pb-Zn,Mo,Oxidized W skarn deposits is high in andradite and lower in grossular;The garnet in Fe,Cu skarn deposits is poor in(spessartite+almandite+pyrope),The garnet in Au,Pb-Zn,Oxidized W,Mo skarn deposits is relatively rich in(spessartite+almandite+pyrope);The content of the garnet in Reduced W skarn deposits is high in grossular and lower in andradite,and it's rich in(spessartite+almandite+pyrope);The content of the garnet in Sn skarn deposits belongs to the grossular-andradite series,(spessartite+almandite+pyrope)vary widely.Garnet in different skarn-type deposits has different mapping zone in triangular mapping of spessartite-almandite-pyrope.Garnet in different skarn-type deposits has different REE:1,Different distribution of REE.The garnet in Fe skarn deposits has left-oblique curves,right-oblique curves and gentle-oblique curves;The garnet in Cu,Oxidized W skarn deposits has left-oblique curves and right-oblique curves;The garnet in Au?Reduced W?Sn skarn deposits mainly has left-oblique curves;The garnet in Pb-Zn skarn deposits mainly has right-oblique curves.2,Different total amount of REE.REE is widely distributed in Fe,Oxidized W and Sn skarn deposits,and REE is relatively concentrated distribution in other skarn-type deposits.3,Different mean of REE.REE is higher in Fe,Cu skarn deposits,and secondary in Oxidized W,Reduced W,Sn skarn deposits,low in Au,Pb-Zn skarn deposits.Garnet in different skarn-type deposits has different mapping zone in graphics of Y-REE,LREE-HREE,LREE/HREE-La/Yb and La/Ho-Y/o.Garnet in different skarn-type deposits could the metallogenic environment.The garnet in Fe,Cu,Au,Pb-Zn skarn deposits indicates high oxygen fugacity,alkalinity,and high water-rock ratio mineralization environment;The garnet in OxidizedW?Sn?Mo skarn deposits indicates relatively high oxygen futility,weak acid-alkaline andrelatively high water-rock metallogenic environment;The garnet in Reduced W karn deposits indicates low oxygen fugacity,acid and low water-rock metallogenic environment.Hanxing iron deposit and SanDaozhuang molybdenum deposit:the end member of garnets are dominated by andradite,and(spessartite+almandite+pyrope)component is low in Hanxing iron deposit,however is relatively higher in SanDaozhuang molybdenum deposit.The garnets in the above two mineral zones develop zonation patterns and hyperplastic edges,indicates that the environment and the composition of hydrothermal components fluctuate during the formation of garnet,not formed under completely closed equilibrium conditions.Indicating that the temperature,pH,oxygen escape and salinity of the metallogenic fluid are constantly changing,implying the fluid is multistage and multistage.Garnet with hyperplastic edges may undergo numerous changes in physicochemical conditions during the growth process,and these changes are mainly caused by multiple surges in the magmatic intrusion process. |
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