Geology, mineralization styles and age of ore-hosting rocks of the Proterozoic Longbohe-Sin Quyen Fe-Cu belt: Implications for regional metallogeny

摘要

A number of Proterozoic Fe-(Cu) deposits or prospects are distributed along the Ailao Shan-Red River shear zone (ASRR) in South Yunnan, China and northern Vietnam, defining the potentially important Longbohe-Sin Quyen Fe-Cu belt. This belt was tentatively considered to be initially part of the Proterozoic Kangdian Fe-Cu province in southwestern Yangtze Block (SW China) before being southeastward displaced into the Cenozoic ASRR. However, such a model is still not confirmed convincingly due to poor understanding of ore genesis of the belt and lack of comprehensive comparisons. In this paper, we described the geology and mineralization styles of typical deposits, the Longbohe and Sin Quyen deposits, in the Longbohe-Sin Quyen Fe-Cu belt, and obtained new zircon U-Pb ages of ore-hosting rocks and intruding granites to evaluate if this belt is comparable with the Kangdian Fe-Cu province. Both the Longbohe and Sin Quyen deposits, which are located in northwestern (south Yunnan, China) and southeastern (northern Vietnam) sections of the belt, respectively, are hosted in volcanics-edimentary rocks that were traditionally named as the Longbohe and Sin Quyen groups, respectively. Both the ores and hosting rocks in the two deposits are variably metamorphosed or deformed, but our results reveal that both deposits have similar paragenetic sequences including pre-ore Na alteration and early Fe-REE mineralization (magnetite and allanite), followed by Cu mineralization (chalcopyrite). Such mineralization styles are broadly comparable to those of the Fe-Cu deposits in the Kangdian province.