广东省新榕锰矿地质特征及成因探讨

Geological Characteristics and Genesis of the Xinrong Manganese Deposit, Guangdong Province

新榕锰矿是广东省重要的锰矿床 ,主矿体产于地下岩溶空洞内 ,矿石中伴生银的平均含量达 10 0×10 -6以上。锰矿石中含有少量的脆银矿、溴角银矿、含锑银黝铜矿、银金矿、单斜绿铜锌矿、黄铁矿、磁黄铁矿及重晶石等矿物。据各类岩石、矿石的矿物成分 ,以及成矿元素、稀土元素地球化学特征等方面研究 ,认为Fe、Mn成矿物质主要来源于元古宇云开群和泥盆系桂头组中的富铁锰质岩层 (锰铝榴石片岩、含锰千枚岩 ) ,部分来源于矿区北部断裂带中的热液硫化物 ,伴生元素Ag、Pb、Zn等也来源于矿区北部断裂带的热液多金属硫化物。有机质 (微生物 )可能参与了成矿物质的风化淋滤、迁移、沉淀富集等成矿作用。地下岩溶空洞是最有利的成矿场所。锰矿的成矿期为新生代。

The Xinrong deposit is a well_known manganese deposit in Guangdong Province. Its ore is of top_quality. There exist such accompanying elements as Ag, Pb and Zn in the ore. The silver content of ore is higher than 100×10 -6 on average. The aim of studying its geological characteristics and genetic type is to serve mineral prospecting. The main orebody of the Xinrong manganese deposit is located in the underground karst cave, between Devonian Guitou and Qiziqiao Formations. Its shape is controlled by the underground karst cave. The secondary orebodies lie in the fault belt. The underground karst cave seems to be the most favorable location for manganese mineralization.By such means as microscopic observation, chemical analysis, X_ray diffraction, and electron microprobe analysis, minerals like stephanite, bromargyrite, Ag_Sb_tetrahedrite, electrum, rosasite, pyrite, pyrrhotite and barite are discovered for the first time in the deposit, which are small grains among or between Fe_Mn minerals. According to the content of metallogenic elements and geochemical characteristics of REE in rocks and ores, the authors have reached the conclusion that Fe and Mn ore materials came mainly from manganiferous terranes (spessartine schist and manganiferous phyllite) of Proterozoic Yunkai Group and Devonian Guitou Formation, and subordinately from hydrothermal sulphide mineralized zone in the north of the mining area, and that the source of accompanying elements like Ag, Pb and Zn is the hydrothermal sulphide mineralized zone. The organic matter (microorganism) may affect weathering, leaching, migration, precipitation and enrichment of ore_forming materials. The metallogenetic epoch is Cenozoic. The Xinrong manganese deposit is genetically of migration_karst accumulation type.