Oxidation-reductionstate of magma in general and granitoid in particular is important for determining themetallogenetic potential of magma bodies. Redox conditions help to interpret the specialized chemistry of geochemistry not only at the content level, but also on the geochemical behavior of the elements. The research on primary inclusions of magma by hermobarogeochemical method of RAMAN equipment has identified that Ngoc Tu granitoid block is in the oxidized state indicated by CO2-rich primary inclusions. This condition shows that the Ngoc Tu granitoidblock is not favorable for the metalogical potential of Sn, but it can be advantageous for the movements of Mo, W from magmatic solution into ore solution.
Wolfram mineralization in the area of Vau village (Dong Giang district, Quang Nam province) is distributed along the small stream together with other sulfide mineralizations in the form of small to large boulders. Ore minerals are mainly sheelite, pyrhotite, arsenopyrite a little of chalcopyrite and pyrite. The ore is distributed in stockwork type in the gray, light gray metamorphic sedimentary rocks with quartz - mica composition alternated with quartz feldspar mica schist, sericite schist and sericitized schist of the A Vuong formation (Sequene 3). Sheelite exists in the area manifested by hornflization and bezeritization. Ajacent area have weak skarnation. They have manifestations of the wolframite deposit of skarn type. Geochemical characteristics: W in the ore reaches 2,323 ppm (0.023%), As - 110,366 ppm (1.10%), Co - 212.3 ppm, related granite (Ba Na block’s granite) reaching 1,517 ppm wofram situated at the edge of the magma block (fine-grained alaskite, similar to the composition of boulders in the ore strip). There is small-grained granite with a content of 794 ppm at the center of mass. Thus, the two granite types have high level of metallogical specialization of wolframite (Ktt = 397 is fine-grained granite and Ktt = 758.7 is alaskite Granite). Besides, this rock has metallogical specialization of As (277.4 ppm in fine-grained granite, 29.9 ppm in alaskite).
Based on the research results on petrographic - mineralogical characteristics, tectonic structural features, geochemistry of major and trace elements of the bedrock, alternative rock, ore, soil, mineralogical geochemistry, mineral facies, inclusions, the origin of ore formation related to oxidized granite and skarnoid - typed metasomatic process in Kon Ra copper ore field have been identified. Petrological and mineral characteristics indicate the process of transitional metasomatism between the skarn and hornfels, also known as bimetasomatic stage (skarnoid deposit type). Diopxite represents the Progade skarnoid stage. Tremolite, actinolite, quartz, chlorite, magnetite, molybdenite, less of chalcopyrite, pyrrhotite, and pyrite indicate the retrogade skarnoid stage. The following is sulfide - quartz stage (major minerals include: quartz, chalcopyrite, pyrite, pyrrhotite, molybdenite). This result is also consistent with the formation temperature 210÷270 0C and the geochemical zoning of elements from intrusive blocks through the outer contact zone that contains the ore and surrounding rocks are as follows: Cu, Zn, Ca (the zone has lime-rich formations), Fe3+, Mo increases in the outer contact zone containing ore closed to acid intrusive rocks. Inversely, the ratios of Pb/Cu, Zn/Cu, and As content increased in the alteration from this zone to the outer one. In addition, uranium mineralization is associated with a later magma stage (pegmatite granite in endo-contact is high uranium radiation: U = 0.17÷0.2%, 3,420,000÷8,020,000 µR/h and contains uraninite).
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