Study On Geology And Elemental Chemistry Of The Jinshizhang Epithermal Silver Polymetallic Deposit In Northern Guangdong, China

Jin Shizhang silver-polymetallic deposit at the northern Guangdong locates in the Southeastern China. A series of calc-alkaline magmatic rock associated with the deposit formed in active continental margin and arc island setting. Geology and element geochemistry of the deposit were studied in this paper and main conclusions are as following:(1) Alteration of wall rock was studied. A series of low temperature wall rock alteration were development in the study area and manganese-bearing altered rocks changed gradually from shallow to depth such as manganic carbonatization facies, manganic sulfide facies and manganic silicate facies successively. Manganese-bearing altered rocks can be weathered into manganese cap at the surface.(2) Occurrence state of silver was studied and the mainly silver minerals are acanthite and stromeyerite. Acanthite occurred with galena formed the Ag-Pb ores, silver minerals occurred with copper sulfide such as covellite, bornite, chalcocite, digenite formed the Ag-Cu ores.(3) Characteristics of elements in minerals acanthite and sphalerite were studied. Sb-rich (max:10.48%), Te-rich (max:24.67%) in argentite and Fe-poor (0.27%~3.47%) in sphalerite indicate that the mineralization have a close connection with the low temperature geological processes.(4) The litho-geochemical and trace element characteristics of volcanic rock (SiO2: 44.86%~51.58%, TiO2: 2.32%~3.65%, P2O5: 0.43%~0.72%, Nb: 19.6×10-6 ~ 64.8×10-6, La/Nb: 0.722~1.47) indicated that the volcanic rock in study area have a similar elemental characteristics with Nb-enriched basalt.(5) According the studies, mineralization types changed gradually from shallow to depth such as Mn-Ag, Pb-Ag, Cu-Ag successively, which is similar with the epithermal.In conclusion, Jinshizhang silver-polymetallic deposit belongs to epithermal deposit. It is the most important prospecting criteria that the manganese cap, low temperature wall rock alteration, manganic mineral, and element assemblage of (Ti),Cu, Pb, Zn, Ag, Sb, (Te).