Yanshanian Magma-Tectonic-Metallogenic Belt in East China of Circum-Pacific Domain(Ⅱ): Lithosphere-Asthenosphere System and Metallogenic Environment

This paper shows that the catastrophe of lithosphere asthenosphere system (LAS) is developed for the Yanshanian metallogenic belt in the East China. Two types of Yanshanian disturbed LAS and metallogenesis in the East China are recognized: great lithosphere thinning and thickening in the compressional orogenic environment, and the related Andes type and Hercyn type metallogenesis, respectively. Great amount of the juvenile and hot mantle materials and the reactivated hot lower crustal materials replaced, heated and injected into the cold lithosphere and crust are believed to be a fundamental source and a basic deep environment for the Yanshanian metallogenic explosion. Reactivated and active discontinuities on the lithosphere scale are considered to be the main ore storing space of the metallogenic zone. Large magma tectonic metallogenic system is necessary for the formation of large cluster area of ore deposit. The eastern China is believed to have large potential for prospecting of ore deposits in terms of the metallogenic environment.

Metallogenic Processes:Evidencesfrom Zoning Patterns of Mineralization and alteration and fluid inclusion geochemistryin the Lehong Zn-Pb Deposit in Northeastern Yunnan, China

1 Introduction The large clusters of Zn-Pb deposits in northeastern Yunnan,located in the southwestern margin of the Yangtze Block,are an important part of the Sichuan-YunnanGuizhou Pb-Zn Poly-metallic Metallogenic Triangle Area

Mineralogy,Fluid Inclusion and H-O-C-S Stable Isotopes of Mengqiguer Uranium Deposit in the Southern Yili Basin,Xinjiang:Implication for Ore Formation

The Mengqiguer deposit in the southern Yili basin Ili Basin is a large interlayer-oxidation-zone type uranium deposit.In this paper,we applied multiple methods including microscopic observation,scanning electron microscope and electronic probe,to analyze the systematical alteration characteristics of the ore-bearing sandstone layer.Fluid inclusion and stable isotope studies on the ore-bearing sandstone have also been carried out to discuss the internal relations between fluid activities,epigenetic alteration and the uranium mineralization.Major epigenetic alteration include clay alteration,carbonatization and pyritization,of which biogenetic pyritization is most closely related to the uranium mineralization.This suggests the existence of microorganism during the uranium mineralization process.The mineralization fluids of low temperature,medium density but varied salinities are suggested to be derived from multi-source,including the meteoric water and organic acidic vapor components from coal-bearing strata.Uranium mineralization,grain-dispersed kaolinite,limonite,colloidal pyrite,and the carbonate cements associated with sulfate-reducing bacteria were formed by meteoric water and vermicular-shaped kaolinite,autologous pyrite,and the carbonate cementation associated with the dehydroxylation of organic matter was formed by organic acidic.Based on these results,we consider that the uranium mineralization and epigenetic alteration both resulted from the reciprocity of organic–inorganic fluid and fluid–rock during the formation of the interlayer oxidation zone.