Brief Analysis on Metasomatism of the Tiaoshan High-grade Iron Deposit in Biyang, Henan Province

The Tiaoshan medium-sized high-grade iron deposit is located in the Erlangping group of East Qinling, southwestern Henan province and is a typical representative of the high-grade iron deposits in the region. The main structural features of the Tiaoshan mining area is the Tiaoshan anticline of NW-SE trend, and the interlayer detachment surface tension space of the fold controls the positioning of main ore bodies. There are two ore belts in the mining area. A ore belt is located in the NE wing of the fold, mainly massive magnetite ore, containing a small amount of disseminated skarn-type ore; B ore belt is located in partial NE wing of the anticline's axis, mainly banded magnetite ore. Ore bodies are distributed in echelon bedding from NW to SE, as layered, stratiform, lenticular, synchronically fold and output with the surrounding rock. From the fabric characteristics of the ore, we can find residues of surrounding rock in massive magnetite ore, whereas, garnet and epidote of early metasomatism in post-magnetite are detected in disseminated skarn-type ore of A ore belt from microscope. It is also found that the contact boundaries of magnetite and banding rock shape like a harbor or isolated island in banded magnetite ore of B ore belt from microscope, showing that the formation of the Tiaoshan high-grade iron deposit is mainly of metasomatism. From Devonian to early Carboniferous, the collision closed process of back-arc basin in Erlangping group leads to the presence of a large-scale mineralization in the region, the Tiaoshan high-grade iron deposit should be the product of this period of mineralization.