Abstract:

Miaoya REE deposit, located in the transitional zone between northeast margin of Northern Daba Mountains and western margin of Wudang uplift, is an oversize Niobium REE deposit associated with syenite carbonatite complexes. The time attribute and structure attribute of Wudang uplift that contains acid volcanic rocks as the main body are the most important basic problems, and the formation of Miaoya REE deposit has a close relationship with them. Miaoya complex is distributed along the fracture structure fragile zone between Yaolinghe group and Meiziya group of the Lower Silurian. NW and NWW faults and folds in the ore area were developed, which provided convenient channels and positioning space for the carbonate rock magma from the mantle to the shallow crust, and had certain control effect on the distribution of niobium, REE ore. From north to south, the syenitecarbonatite complexes consist of three facies belts: edge phase, transition phase and center phase. The wall rock alteration of the complexes has many types such as carbonatization. sericitization, biotitization, albitization and flouritization. Combined with regional geological background and geological characteristics of the deposit, the authors suggest that the carbonate rocks formed after the syenite, has a close relation with the syenite magma, and think that the mineralization material may have come from syenite magmas intrusion, then underwent gas water hydrothermal metasomatism after magmatism period, that is, all kinds of carbonatization alteration impelled niobium and rare earth elements to be enriched and precipitated. Before and after the complexes formation, the complexes were obviously controlled by the tectonic action; the early formed shrinkage cracks in the rock and structural fractured zone created favorable condition for the gaswater hydrothermal metasomatism at the later stage; and the mineralization mostly emplaced in the mylonite of Yaolinghe group. Miaoya REE deposit was produced by the coupling of the syenitecarbonatite that was formed by volcanic eruptions and the Sinian Paleozoic lithostratigraphy during the process of thrustnapping of the syenitecarbonatite with the Sinian Paleozoic lithostratigraphy.

Key words: complexes, carbonatite, REE deposit, Miaoya