Study On Geological, Geochemical Gharacteristics And Genetic Gynamics Of Shalagang Antimony Deposit In Southern Tibetan Detachment System

After the collision of Indian plate and Asian plate, the Southern TibetanDetachment System which moves as extending and detaching formed in the south ofYarlung Zangbo Suture, and the Southern Tibet antimony metallogenic belt is locatedin it. The geology of ore deposit character, mineralogy character, material sources,genesis and ore-forming epoch of Shalagang antimony which is one the mostrepresentative deposits of the Southern Tibet antimony metallogenic belt are studiedparticularly, and it makes some new cognitions and improvements in the dissertation.The investigation indicates that the Shalagang antimony has osculatingrelationship with the Structure but has no selectivity with the host rock: The ore bodyis controlled by the fault zone, which insert into it as a nervation;The host rockincludes chert, carbonaceous slaty rock, altered diorite , altered diabase and so on. Theore-forming epoch of Shalagang antimony is obviously later than era of the host rock,so it is concluded that the Shalagang antimony maybe formed in the late Himalayan.The study of the mineralogy indicates: (1)Few impurity and poor sulfur in thestibnite of Shalagang antimony. (2)From the stibnite's cell parameter, it finds that thecell parameter of Shalagang antimony's stibnite approachs the standard value. And iteduces the forming temperature of the stibnite is between 150℃～200℃. (3)Thequartz in different period have different thermoluminescence curve, and thethermoluminescence curves of the quartz in rich ore(main metallogenic period) havethe characters of gently curve, unconspicuous peak and the luminous intensity has therelationship of positive correlation with the temperature.The fluid inclusions of Shalagang antimony are composed of gas and liquidfacies. The composition of gas facies is CO2 and vapor, and the liquid facies is brinesolution. The homogeneous temperature of inclusions is between 135℃～290℃,according to the forming temperature of stibnite. And the salinity of inclusions is0.53～12.58wt%NaCl. So the fluid inclusions is low temperature and low salinity.The character of isotope geochemistry indicates: The value of the δD is between-151‰～-160‰, indicates that sources of ore-forming fluid is from meteoricwater, according to the result of fluid inclusions which are low salinity and lowtemperature. The achievement of Rb-Sr isotope and lead isotope prove that thesources of metal maybe come from the basement of basin in the passive continentedge;and the sulfur isotope indicates the sulfur sources as deep origin.Depend on the physical geography and areal geology, dynamics mechanism andmode of Shalagang antimony forming are discussed. Finally, it indicates that theShalagang antimony has three characters: (1)The mineralization is controlled by theprocess of detachment after the impact between indian and Eurasia, and has arelationship with intrusion of the diorite in the mine. (2)Ore-forming liquid is made upof meteoric water. (3)Material sources comes from mantle or mantle-crust hybrid,indicating that the material and energy interchange occur between mantle and crust.