| The Yin ChangGou Pb-Zn deposit is located in the east of Jinsha river metallogenic belt in Yunnan Sanjiang. The tectonic location is in the southern of Zhongdian arc which beteen SongPan and GanZi folded belt. It belongs to the south west wing of Anle fold structure which in the range of Tuoding-Kaiwen and Zhongdian fracture. The structure movement is frequently in this area and more fracture, frequent fold structure. Aiming at the metallogenic characteristics of Yin ChangGou Pb-Zn deposits on the basis of the work through field geological survey and indoor comprehensive study, analyzed the geological characteristics. Through the ore-forming fluid and isotopic geochemical studies, this paper expounds the fluid property and the source of ore-forming materials. Besides thtose, the paper analysis the structure which related to mineralization and summarizes the rule of ore-controlling structure. On the basis of these features, it explores the ore formation.After field survey, there are two different ore types found. A type of minerals produced in the layered, bedded ore bodies with a typical banded, laminated structure. The characteristics of minerals are mainly fine-grained pyrite, sphalerite. Another type of minerals mostly exists with quartz and calcite as symbiosis by stockwork outputs which contacts with fracture fissures closely. The characteristics of minerals are mainly Coarse-grained sphalerite and coarse-grain galena.After research and areal geology, geology of mineral deposits combination, there is a set of Carbonate rock by sediment at the time of Caledonian-Variscan early, and the ore source bed is initially made by mineral; In the late Variscan-Indo-China early, there are Fold uplift and Fault structures occurred, the Mineral ore deposits in favorable areas by the the tectonic shift effect; In late Indo-China, deposits are thicker and enrichment, there is still a small part of mineralization in the Yanshanian, and deposits is basicly shape.Shangri-La Yin Changgou lead zinc ore is affected by structure and lithology. The main ore exists in the broken dolomite of upper Cambrian series, which is affected by folds and faults obviously.All the data of fluid inclusions geochemistry show that the ore-forming fluids are CO2-H2O-NaCl system, the homogenization temperatures are in the range of 190-270℃, the salinities 2.99%-12.75% NaCl equiv, the fluid density are from 0.69-1.02g/cm3, and mineralization pressure 36.9×106-101.7×106Pa. It conclude that the deposit is medium-low temperature and salinity, low density shallow metallogenic type.In terms of sulfur isotope analysis from sphalerites and galenas, theδ34S value ranges mainly between-1.28‰～17.79‰, which is coincident with the averageδ34S value 6.245‰. The initial sulfur in this deposit is mostly derived from strata sediment and sphalerite. The lead isotope compositions of sphalerites and galenas are comparatively concentrate,206Pb/204Pb= 17.626～17.856(average 17.739), 207Pb/204Pb=15.583～15.690(average 15.615),208Pb/204Pb=37.706～37.954(average 37.762), it explains the silver deposits belong to lead isotope stable uniform type. The lead should mainly be derived from strata sediment and orogenic belt. In terms of carbon and oxygen isotope datas, the compositions of calcspar in vein ore bodies areδ13C=-4.76‰～-0.19‰,δ8OSMOW=17.88‰～21.35‰, shows that the carbon and oxygen of vein ore bodies are derived from carbonatitic layer.It is concluded that the YinChangGou Pb-Zn ore deposit is a typical Stratabound deposit, which is characterized by multiple metallogenesis, multiple ore-controlled factors, polymaterial sources and polygenetic types. |
PDF Full Text Request