The Intermediate-acid Intrusive Magmatism And Mineralization In Qimantag, East Kunlun Moutains

Geodynamic evolution process and metallogeny is an essential research field all over theworld. Meanwhile it has been drawn more attentions to the relationship betweenmantle-derived magmatism, magma mixing and continental evolution, large-scale metallageny.Qimantag region, as an important part of northern Tibetan Plateau, is located in the structuralknot of Altyn, East Kunlun, Qadam block, and has experienced five tectonic evolutionarystages: craton formation in Archean-Palaenproterozoic era, palaeocontinental break-up andsupercontinent coverging in new Proterozoic era, ocean-continent transition in earlyPaleozoic-early late Paleozoic era and late Paleozoic-early Mesozoic era, incontinentaloverprinted orogeny in Meso-Cenozoic era. The metallic ore deposits in this aera are relatedwith magmatism, especially Paleozoic-early Mesozoic magmatism. The degree of research onmagmatism and mineralization is very low. Regarding typical intermediate-acid intrusiverocks and related deposits as research objects, the paper studies on relationship betweenintermediate-acid intrusive magmatism and metallageny in Qimantag area, revealsmetallagenic system developmental mechanism, metallogenic material aggregation processand metallogenic mechanism on the basis of theory of plate tectonic evolution. After buildingregional structure-magma-metallogenic model mainly with crust-mantle interaction andconcluding prospecting criteria of different types of deposits according to geological,geophysical and geochemical information, the paper presents prospective areas. Mainprogresses and achievements are as follows:1. The main ore-bearing strata of skarn-greisen-quartz vein type tungsten-tin deposits isXiaomiao Formation in Changcheng Period which is important source bed of W, Sn.Liangyashan Formation in Jixianian Period provides parts of mineralizing materials, and isthe ore-bearing horizon of layered skarn type Pb-Zn deposits. And interlayer carbonate is alsothe key factor of Pb-Zn enrichment. The skarn-type iron-polymetallic deposit often occurs inQimatag Group (Tanjianshan Group) in Ordovician and Di’aosu Group in Carboniferous, andQimatag Group (Tanjianshan Group) probably provided parts of mineralizing materials.2. Main types related with intermediate-acid intrusive magmatism includeskarn-greisen-quartz vein type tungsten-tin deposits, porphyry Cu-Mo deposits, skarn type Fe-Cu-Pb-Zn polymetallic deposits, layered skarn type Pb-Zn deposits and some rare-elementand REE deposits with alkali granites. The metallogenic epochs are early Paleozoic, latePaleozoic, early Mesozoic eras, which are closely related to the early Paleozoic-late Paleozoictectonomagmatic cycle and the late Paleozoic-early Mesozoic tectonomagmatic cycle.3. The tonalites and monzogranites are A-type granites forming in Silurian (429~430Ma),and are closely related to the skarn-greisen-quartz vein type W-Sn mineralization.Metallogenic epoch was427±13Ma. The main ore forming materials were derived ultimatelyfrom the crust. Ore-forming fluid shows some characteristics of magma water and belongs toNaC1-H2O-CO2system with medium-high temperature, middle salinity and low density. Theimmiscibility of fluids is the main factor to form quartz-vein type ore bodies.4. The Early-Middle Devonian granodiorites, quartz diorite, and monzogranites,dominating by I type granite, are related with skarn-type iron-polymetallic deposits. The mainore forming materials and fluid are derived from magmatic activity.5. Porphyry type Cu-Mo deposits, skarn type Fe polymetallic and layered skarn typePb-Zn deposits are closely associated with the granodiorites, quartz diorites, monzogranites,which belong to I+A type granites. The chief genesis is mantle underplating and remelting ofancient continental crust. The petrology, geochemistry, Sr-Nd-Hf isotope and Zircon U-Pb ageof granodiorite, dark enclaves, porphyaceous monzogranites are similar in Kaerqueka oredistrict, with εNd(t)(-5.3~-4.2) and εHf(t)(-8.6~-1.6). These features indicate that there maybe homogenization magma mixing during the process of crustal and mantle materials mixing.The Re-Os model age of porphyry type Cu-Mo deposits in Kaerqueka is245.5±1.6Ma.And the ore forming materials of porphyry type Cu-Mo deposits in Kaerqueka origins fromcrust and mantle. The ore-forming fluid is derived from magmatic hydrothermal activityfeatured by high-temperature and high salinity. The boiling of ore-forming fluid contributes tomineralization. The ore-forming materials of skarn type deposits, such as Galinge, have themixing sources of crust and mantle. The mineralization is related with the reaction betweenmid-high temperature magmatic hydrothermal liquid and wall-rocks. The ore-forming fluid oflayered skarn type Pb-Zn deposits is magma fluid system enriching in CO2and CH4, withcharacteristics of middle-temperature, high salinity. The meteoric water is partly mixed inlocal areas, such as Hutouya. The ore forming materials are also from both of crust and mantle.6. The alkali granites, A-type granite, is formed in post-collisional extensionalenviorment at the end of late Triassic era (~210Ma), and is closely related with rare elementsand REE mineralization, whose major ore minerals are pyrochlore and allanite.7. After organizing the tectonic-magmatic-mineralization model and concludingprospecting criteria of different types of deposits, the paper proposes five prospecting areassynthesizing geophysical and geochemical informations: Baiganhu-Galesai W-Sn prospectingarea, Tanbeixuefeng-Wulanwuzhuer Cu-Fe polymetallic prospecting area,Weibao-Yemaquan-Haxiyatu Fe-Cu-Pb-Zn polymetallic prospecting area, KaerquekaCu-Fe-Mo prospecting area and Yeniugou-Tuyaodong Fe, rare elements and REE prospectingarea.