| Gyantse-Lhunze gold-antimony metallogenic belt in Tibet as the research object, this thesis, which is based on the item of Tibetan Mineral Resources Potential Assessment, systematically expounded the ore-forming geological background and mineral distribution rule of the Gyantse-Lhunze gold-antimony metallogenic belt. With depth analysis of the ore-forming geological conditions, the ore-forming regularity and metallogenic model are summarized, and favorable prospecting areas based on metallogenic prospective analysis are reported in this thesis.Gyantse-Lhunze area is located in the southern Qinghai-Tibet Plateau, the Tethys Himalayan area(TH). The main research object of this thesis is at the east end of the gold-antimony metallogenic belt in the south Tibetan detachment system, which is located between STDS (major detachment surface of the south Tibetan detachment system) and IYS (the Indus-Yarlung Zangbo River suture zone). Since the middle-later of 1960s, a large number of gold-antimony ore deposits (prospects) has been found in this area, with good gold-antimony ore propects, such as the Shalagang, Cheqiongzhubu, Mazhala, Chalapu, Nagarze, and so on.Through detailed studies on the ore-forming geological background (such as tectonic location, regional strata, regional structure, regional magmatic activity, regional metamorphism, and so on), geophysical, geochemical and remote sensing geology and regional mineral characteristics of the Gyantse-Lhunze area, the author placed emphasis on mineralization backgrounds, deposit geological characteristics of five antimony-gold typical ore deposits, the Shalagang, Nagarze, Chalapu, Mazhala and Cheqiongzhubu, discussed the metallogenic epoch of each deposit, ore formation mechanism and ore-forming process, and established typical metallogenic models for these typical ore deposits. After describing ore control factors in detail, such as geotectonic environment, lithology, structure, magmatic activity, metamorphism, etc, the paper concludes that the formation of the antimony-gold typical ore deposits in this area, which are controlled by stratum(the Triassic to the Cretaceous), lithology(black carbonaceous sand-slate, carbonatite, siliceous rock, etc), structure(fold structure + metamorphic core complexes system + fracture + interlaminar fracture zone), magmatite(New Himalayan period magmatic activity) and metamorphism, are "Five integrated". With different role of the mineralization, different combination of ore-controlling factors belongs to different stage of the sedimentary-reform-superposition mineralization.This paper systematically summarized the metallogenic regularity of the Gyantse-Lhunze Gold-antimony Metallogenic Belt. The study shows that the antimony-gold typical ore deposits in this area, whose metallogenic epoch are focused on 14~34Ma and closely related to the new Himalayan period tectono-magmatic activities, are mainly distributed in clastic rock and carbonate strata of late Triassic, Jurassic and Cretaceous. In space, the ore deposits, with distributed characteristics of subsection in EW, zonation in NS and circle belts around the metamorphic core complexes, are mainly controled by nearly EW and SN-trending faults. Detailed research on regional tectonic evolution, mineralization and metallogenic model shows the formation of the antimony-gold ore deposits in this area mainly experienced three important stages, that are the formation of initial beds in late Triassic-early Cretaceous, transformation of dynamic metamorphism hydrotherm between late Cretaceous and Oligocene(70~23Ma),superimposed and enriched mineralizations of the volcanic-secondary volcanic magmatic activity in Miocene neogene(23~8Ma).Based on study of regional mineralization backgrounds, typical ore deposits, ore-controlling factors and ore-forming regularity, the author analyzed the mineralization vision of the south Tibetan Gyantse-Lhunze Gold-antimony Metallogenic Belt. This paper considers that peripheral area of Ranba and Qiongduojing metamorphic core complexes, which lies along the south of Qiongduojing deep fault, is the best metallogenetic location of rock gold; along the Luozha deep fault in the south of the Metallogenic Belt, the intersections of nearly EW and SN-trending faults, in the transition parts of the graben-horst type structure, are the most advantageous environment for the antimony deposits; while the Rongbu-Gudui fault zone in the south of the Metallogenic Belt is the most advantageous location of the antimony-gold ore deposits. According to detailed research on geophysical, geochemical and remote-sensing information, this paper established a comprehensive prospecting model of five antimony-gold typical ore deposits, the Shalagang, Nagarze, Chalapu, Mazhala and Cheqiongzhubu, and their metallogenic prospecting marks on geological, geophysical and geochemical, etc. On the basis of study on typical ore deposits in this area, regional ore-forming geological conditions, regional geochemical exploration achievements and remote sensing mineralization(altered) information, etc, four metallogenic prospective areas can be proposed: Ranba-Nagarze metamorphic core complexes area(V1); Qiongduojing metamorphic core complexes area(V2); Xiaba-Xuela area(V3); Zhegucuo-Mazhala area(V4). And finally, the author illustrated the feature and prospecting direction of the four metallogenic prospective areas separately. |
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