Ningwu Mining District, Dangtu Co., Ma'anshan Prefecture, Anhui Province, China

The Ningwu District includes the NNE- and NE-trending Late Mesozoic Ningwu and Fanchang volcanic basins. The basement consists of Triassic and Jurassic sedimentary rocks that are exposed in the surrounding area. The volcanic rocks include alkaline basalt, basaltic andesite, trachyandesite, andesite, trachyte, dacite and phonolite. Subvolcanic intrusions, consisting of gabbro-diorite porphyry, diorite porphyry, quartz monzonite, granite, olivine gabbro, albite diorite and albite porphyry, are widely distributed in the area. They occur as stocks with well-developed porphyritic textures, and are emplaced less than 1 km from the surface. Intrusion-hosted Fe deposits in the Ningwu District are commonly situated in the middle to upper parts of the subvolcanic intrusions, particularly in gabbro-diorite porphyries. Skarn Fe ore bodies are mainly distributed in the fringe areas of the volcanic basins, within the contact zones between the subvolcanic intrusions and Triassic calcareous shales and gypsum-bearing carbonates. Other types of Fe ore bodies include those in fracture, fault and breccia zones in fringes of the subvolcanic basins, and veins at the top of the subvolcanic intrusions. Hydrothermal vein type Cu-Au deposits are distributed within or around the volcanic calderas, and are controlled by faults and fractures.

Ref.:
- Yuanming Pan and Ping Dong (1999): The Lower Changjiang (Yangzi/Yangtze River) metallogenic belt, east central China: intrusion- and wall rock-hosted Cu-Fe-Au, Mo, Zn, Pb, Ag deposits. Ore Geology Reviews 15, 177-242.