XINQIAO IRON-DEPOSIT FIELD IN TONGLING, ANHUI ——GEOLOGIC AND GEOCHEMICAL CHARACTERISTICS AND GENESIS
ZANG Wenshuan, WU Ganguo, ZHANG Da and LIU Aihua (College of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China)
The genesis of Xinqiao iron deposit has been debated over the past 20 years. Several hypotheses, i.e. sedimentary-modified deposit, strata-bound skarn deposit, submarine exhalative-sedimentary deposit, have been postulated to account for the mineralization of the iron deposit. A model of the two-stage mineralization was put forward in this paper on the basis of the geologic and geochemical data of the Xinqiao iron deposit. The early mineralization is related to sedimentation, which resulted in the formation of the siderite ore-body and some pyrite ore-bodies. The later mineralization is associated with the Mesozoic magmatism and resulted in the formation of the stratiform and stratoid sulphides, the skarn-type orebodies and vein-type orebodies. These orebodies formed at the different mineralization stages have distinct geologic and geochemical characteristics.