Characteristics and Genetic Significance of Skarn in the Gaerqiong Cu-Au Deposit,Ge'gyai,Tibet

The petrologic and mineralogical characteristics of the skarn in the Gaerqiong copper-gold deposit were studied in this paper.The skarn is mainly distributed in the contact zone between marble and quartz diorite as well as granite porphyry.It is distributed vertically as the zoning of marble-silicified hornfels-skarnized marble-wollastonite skarn-diopside skarn-garnet skarn-quartz diorite.A study of petrochemical,rare earth and trace element characteristics of the skarn-type ore shows that the skarn is calcic skarn,which has characteristics of weak negative Eu anomalies and LREE enrichment as well as the enrichment of large ion lithophile elements such as Rb,Th,Cs and U and the depletion of high field strength elements such as Hf,Ti and Y.The geochemical characteristics of skarn are controlled and affected by marbles,quartz diorite and granite porphyry.It is held that the skarn is genetically closely related to marble,quartz diorite and granite porphyry.Based on a discussion on the formation background of the Bangonghu-Nujiang metallogenic belt and the temporal-spatial relationship,the authors consider that the Gaerqiong deposit is a magmatic hydrothermal contact metasomatic type ore deposit.