Metallogenic Regularity And Crustal Evolution Of Altay Deposit Enriched Region In Xinjiang, China

The Altay noble metal,nonferrous metal,rare metal and nonmetal deposit enriched regionis located in northern Xinjiang,has many anomalous geological phenomena to have beenrevealed,and has attracted the attention of many Chinese and foreign geologists.With the theory of metallogenic series as the guidance,the paper has an attempt to usefundamental ore deposit geology to elucidate crustal evolution.Some new results are obtained asfollows:1. In the light of the concept of metallogenic series advanced by Cheng Yuqi,ChenYuchuan et al., the noble metal,nonferrous metal,rare metal and nonmetal deposits of Altaydeposit enriched region might be assigned to three metallogenic series and five metallogenicsubseries related to late Caledonian-Hercyanian mantle-mainly derived,mantle-crust mixedderived magma.2. Based on studies on the time-space distribution and migrating evolution of deposite andore materials,it has been revealed that there exists Fuyun-Keketuohai deposit enriched center inthe Altay deposit enriched region.The known large and superlarge deposits concentratedlyoccur in the center, in which rare metal deposits exist in the inner center, nonferrous metal inthe outer center,noble metal deposits around the center.Ore materials might be mainly derivedfrom the mantle,partially from the crust.3. There exists Caledonian-Hercyania magmatic activity center located in Fuyun-Keketuohai in the Ahay deposit enriched region.Mantle-derived magmatic activity clearly tookplace at the center,whereas crust-mantle mixed derived and crust-derived magmatic activitiesoccurred around the center.From the center to perphery,metamorphisms vary from granizationto gneissification,to schist and to light-nonmetamorphic rocks.4. Metamorphism and tectonism are distributed in the form of sem-concentric rings,withthe center located in Fuyun-Keketuohai.5. The Altay deposit enriched region might be a gechemical anomalous field rich inelements Cu,Au,Ni,Pb,Zn,Fe,Ag,Nb,Ta,Sb,Hg,K,Na,S,P,F,Cl,which might be enriched in themantle,and Li,Be,which might be mainly enriched in the crust.6. Based on the discussions above,it is proposed that the crust-mantle metallogenicsystem and the three subsystems of enrichment,trans-ferring and locating for ore materials ofthe Altay deposit enriched region.7. On the basis of the comprehensive studies of various information such astectonism,magmatism,metamorphism,metallization,and their evolution in space and time,andgeophysics,the formation and evolution (three accordion opening-closing events) of Altaydeposit enriched region are considered to have been caused by the inception and evolution ofPaleozoicAltay mantle plume-generated triple junction rifts.Ascending and later adspreading ofthe mantle plume opened the triple junction rifts,resulted inthe continental break-up,andgenerated Altay "ocean island-type" ophiolites,Altay-type grantoids,granization,high-teperature and low-pressure metamorphic belt and chief large-superlarge deposits in theenriched region.Subsiding or resting of the mantle plume caused the A-type subduction,closingand orogeny of the triple junction rift system,and yielded triple-type intracontinental orogenicbelts,synorogenic granitoids and some mineral deposits.