宁芜向山式黄铁矿床的地质特征和成因

向山式黄铁矿床是宁芜玢岩铁硫成矿系列的中部矿,与铁矿体紧密伴生,矿床规模大、品位较高,伴生硬石膏矿可同时开采。矿体产于宁芜早白垩世大王山组火山隆起构造的衔接部位,处于次火山岩体相对凹陷的接触蚀变带中。从硫同位素、Co/Ni 值及测温数据等判断,矿床形成具有同生沉积-火山气液双重物源,下伏含膏岩系提供了主要的硫源。

GEOLOGICAL CHARACTERISTICS AND ORIGINATION OF XIANGSHAN-TYPE PYRITE DEPOSITS ACROSS NANJING-WUHU REGION

Known as the middle minerlization of the porphyrite iron-sulfur metallogenetic series across Nanjing-Wuhu region,Xiangshan-type pyrite deposits are frequently associated closely with iron mineralization,with large reserves,high grades and usable accompanying anhydrite resources.The ore bodies occur along the border between two volcanic domes in the relatively low,contact metamorphic zones of subvolcanic rocks with the Dawangshan formation of early Cretaceous age.Sulfur isotopic composition,Co/Ni ratio and thermometric results all lend support to the argument that this type of pyrite deposits should be attributed to the a twofold process,syngenetic deposition together with volcanic gas-liquid effusion,the under- lying gypsum-bearing rocks providing them with considerable amounts of sulfur.