Superimposition Mineralization And Exploring Model In The Yangla Mctallogenic Belt, Western Yunnan

The Yangla metallogenic belt located in the middle section of Jinshajiang tectonic belt,the Yangla copper deposit and the Luchun Cu-Pb-Zn deposit are two of several Cuoccurrences located along the Yangla metallogenic belt. Previous studies have reportedthat the Yangla metallogenic belt was formed by a process of the volcanic exhalative andsedimentary mineralization. In this paper, based on previous geology data, selecting Yanglacopper deposit, Luchun Cu-Pb-Zn deposit to research. Based on field observations andlaboratory analyses, studying the characteristics of ore-controlling structure, geochemistryof the volcanic rocks, geochemistry of the Yangla granodiorite, geochemistry of copperores, the age of metallogenesis, the age of the Yangla granodiorite, origin of ore-formingmaterials. The superimposed mineralization of the Yangla metallogenic belt and oregenesis are discussed, and obtaining the following understand and progress:(1) The Yangla copper deposit was formed in the Jinshajiang rifted backarc basin,the ore bodied was controlled by the stratigraph, petrology and structure, the REEdistribution patterns and the primitive-mantle-normalized trace element patterns of themainly ores of the Yangla copper deposit are similar to the Yangla volcanic rocks(Hercynian), immobile elements ratios (Zr/Hf,Th/Nd,Nb/Nd,Y/Nd) of the ores are closeto the volcanic rocks, indicates the Yangla copper deposit was formed by a process of thevolcanic exhalative and sedimentary mineralization in Hercynian.(2) The primitive-mantle-normalized trace element patterns of the ores of the Yanglacopper deposit are similar to the Yangla granodiorite, which is collected from the quartzand sulfide veins in the orebodies and the wall rock of Yangla copper deposit；immobileelements ratios (Zr/Hf,Th/Nd,Nb/Nd,Y/Nd) of the ores (Indosinian) are close to theYangla granodiorite; the Yangla granodiorite formed at 234.1±1.2 Ma to 235.6±1.2 Ma,thequartz and sulfide veins in the orebodies of the Yangla copper deposit yield molybdeniteRe–Os isochron age of 232.6±2.9 Ma, the ages of metallogenesis in Indosinian andcrystallization of the granitoids are the same, within error, indicates the Yangla copperdeposit was formed by hydrothermal mineralization in Indosinian. The ores of the LuchunCu-Pb-Zn deposit owned the sedimentary characteristics of the banded and stratifiedstructure; the REE distribution patterns and the primitive-mantle-normalized trace elementpatterns of the ores of the Luchun Cu-Pb-Zn deposit is similar to the Luchun volcanicrocks and the Luchun slate; the ore body of the Luchun Cu-Pb-Zn deposit yields Pb mean model age of 182.8Ma, which is close to the age of the Luchun volcanic rocks, indicatesthe Luchun Cu-Pb-Zn deposit was formed by a process of the volcanic exhalative andsedimentary mineralization in Indosinian.(3) The KT6 KT15 orebodies of the Linong ore block, KT1, KT2 and KT3 orebodiesof the Jiangbian ore block in the Yangla copper deposit, was controlled by the steep faults,which crosscuts the granodiorite in Yanshan, implies that the ages of metallogenesis islater than the crystallization of the granitoids in Yanshan, the deposit was formed by thehydrothermal mineralization in late Yanshan Himalayan. The Luchun Cu-Pb-Zn depositdeposit was associated with the thrust faults in Indosinian, the thrust fault crosscuts theLuchun volcanic rocks (Indosinian), indicates the Luchun Cu-Pb-Zn deposit was formedby the late Yanshan hydrothermal mineralization in Himalayan.(4) The Yangla copper deposit and the Luchun Cu-Pb-Zn deposit are superimposeddeposits, which were formed by a process of the volcanic exhalative and sedimentarymineralization, and hydrothermal superimposed mineralization.