| Zongwulong tectonic belt is an important geological unit in the northern margin of Qaidam basin with the good mineralization conditions,and a major breakthrough for metallic mineral deposits is expected.In this contribution,the important metallogenic environments of the Zongwulong tectonic belt was discussed based on the studies on petrology and geochemistry of Baluogenguole basic dykes and Xuji diorite,and the ore-controlling factors were also analyzed through geological and geochemical studies of the Xuji Pb-Ag deposit,Gariligen Au deposit and other mineralization occurrences.The main achievements in this study are as follows:(1)Zircon U-Pb dating reveals that the Baluogenguole basic dykes and the Xuji diorite were emplaced at 289±1 Ma and 258±1 Ma,respectively.The former alkali basalt was possible formed by the low degree partial melting of the asthenospheric mantle,which interacted with the lithospheric mantle during the evolution process and extracted the components of the lithospheric enriched mantle,while the latter calc-alkaline diorite may be dominantly derived from the ancient crustal material with minor mantle component addition.(2)Initial break-up of the Zongbulong tectonic belt during the Early Devonian-Early Carboniferous period,which may be favorable to the formation of the skarn deposits.Intracontinental rift continued to expand during the late Carboniferous-Early Permian period,a limited oceanic basin was formed first in the east,and then in the central and western regions,which may be favorable to the formation of conglomerate deposits.The occurrence of ocean-continent subduction during the middle Permian-middle Triassic period is favorable to the formation of skarn type,pegmatite-type,magmatic-tectonic hydrothermal vein type and other deposit types.The late Triassic continent-continent collisional orogeny is mainly presented by shear zones,which may have a certain remodeling /destroying effect on the deposit formed earlier.(3)The orebodies of the Xuji Pb-Ag deposit were mainly hosted in phyllite and intercalated limestone of Carboniferous-Permian Zongwulong Group as east-west veins,which were controlled by the compress-shear thrust faults.The ore-forming materials were mainly sourced from Zongwulong group,and the ore-forming fluid was dominantly post-magmatic hydrothermal origin with high temperature and high salinity.It was therefore belong to tectono-magmatic hydrothermal vein deposits.The orebodies of the Gariligen Au deposit were conformably hosted in the conglomerate-glutenite of Permian Lemengouformation as stratiform or lenticular shape,and As-bearing pyrite and arsenopyrite are the main gold bearing minerals.The mineralization has experienced the paleoplacer deposition period and metamorphic hydrothermal period successively,and therefore the deposit may be a reformed sedimentary conglomerate gold deposit.(4)The main ore-controlling factors and future prospecting orientation in the Zongwulong tectonic belt are as follows: 1)The tectono-magmatic hydrothermal vein Ag-Pb-Zn deposit is controlled by the interlayer of clastic rocks and carbonate rocks in the Zongwulong group,the near EW-NW trending thrust fault,and the intermediate-acidic intrusion in Middle Permian-Middle Triassic.2)The Fe-Au skarn deposit is controlled by the carbonate strata,intermediate-acid intrusive rocks and skarn assemblages.3)The Li-Be-Nb-Ta pegmatite deposit is controlled by granitic pegmatite.4)The conglomerate gold deposit is controlled by conglomerate-glutenite of Permian Lemengou formation,northern margin fault of Zongwulong tectonic belt and its secondary faults.According to the ore-controlling factors of different main target deposit types,the future prospecting orientation of grade A,B and C are classified by integrating geological,geophysical and geochemical data. |
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