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摘要
The Yidun arc is an important part of the Tethys metallogenic domain at the eastern margin of Qinghai-Tibet, in which Cenozoic tectonic magmatism is strong and accompanied by polymetallic mineralization such as Ag-Pb-Zn-Cu-Mo. Recently, the Chictionggou Sn-Be deposit was newly discovered in Yidun Xiangcheng arc, which is characterized by pegmatite-type Be-Rb-La-Cs-Li mineralization and skarn-type Sn-W mineralization symbiosis. The two types of ore bodies are produced around the Hagala granite. Based on the geological, petrological, geochemical and geochronological data of the Yidun arc, this paper discussed the fractional crystallization of the Hagala granite and the Late Cretaceous granites in the Yidun arc and its indication significance of regional tectonics. Zircon U-Pb dating indicates that they were synchronously emplaced at 91. 5 similar to 90. 2Ma, which belongs to the high-potassium calc-alkaline to shoshonite series, peraluminous. The samples are rich in Rb, U, Nd and Hf, but deficient in Ba, Sr, P and Ti, and have obvious negative Eu abnormality. The values of epsilon(Hf) (t) are 3. 9 similar to 0.5 and -4. 7 similar to -1. 3, and the corresponding two-stage model ages (t(DM2)) are 1093 similar to 1372Ma and 1207 similar to 1418Ma. Furthermore, the Chictionggou Sn-Be deposit was formed in the extensional tectonic setting of the Late Cretaceous, and the ore metallogenesis mainly derived from the granitic magma formed by partial melting of the Mesoproterozoic crust. Late Cretaceous, the lithospheric mantle was heated by upwelling asthenosphere materials, and large-scale magmatic activity and mineralization occurred in Yidun arc. The material differences in the heavy melting source area and the different degrees of magma crystallization in the closed system formed Changtai-Xiangcheg-Gezai granite belt and distinct mineralized zoning. The Hagala granite in Xiangcheng arc experienced a high degree of fractional crystallization, and rare metals such as Sn-Be-Rb-Cs were highly enriched in the late stage of magmatic differentiation. Late Cretaceous highly differentiated granites have great prospecting potential of pegmatite-type Be-Li orebodies and skarn-type Sn-W orebodies in Xiangcheng arc.
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单位桂林理工大学
