The Re-Os Analysis Method Improve And Apply To Magmatic Copper-Nickel Sulfide Deposits

Magmatic Ni-Cu-?PGE? sulfide deposit which related to the mafic-ultramafic complex have an impotent role in the global nickel, copper and platinum group element resourse. So, Research the formation mechanism of the Ni-Cu-?PGE? sulfide deposit not only can instruct how to looking for mineral deposits, but also can gain more important information about geological process in the depths, crust-mantle differentiation, magma generation and evolution, geodynamics and so on. Rhenium and osmium are high siderophile element and sulphophile element, Moreover, Rhenium is moderate incompatible element, osmium is compatible element. So, osmium is rich in mantle, rhenium is relatively rich in crust, this conduce mantle and crust to have different Re/Os and ¹⁸⁷Os/¹⁸⁸Os value, As the Re/Os value of the crust is high, addition of more crustal material to the magmatic or metallogenic system would impart hiher positive values of ?os,while Re depletion leads to appearance of negative yos values. So, Re-Os isotopic not only the tool can directly determine the forming age of Ni-Cu-?PGE? sulfide deposit, but also the strong tracer of the magmatic Ni-Cu-?PGE? sulfide deposits forming and a highly sensitive indicator of the crustal material mixed degree.This research uses acetone extraction method to separate and purify rhenium for Negative Thermal ionization Mass Spectrometer ?N-TIMS? determination by improve the alkalinity from 5 mol/L to 10 mol/L.The device used for direct distilling Os from the Carius tube is improved, which reduce the volume of the device and raise the efficiency of the chemical procedure. This method combined with digestging sample with aqua regia in sealed Carius tube, extracting the Re from the residual solution using acetone and measuring the Re and Os on ICP-MS?X7-Series? and NTIMS, The procedure blank of Os is below 3pg, the blank of the Natural abundance Os and ¹⁸⁷Os are 0.2pg and below 0.1 pg respectively.First, we use the method to study the Re-Os characteristic of Tula'rgen Ni-Cu-?PGE? sulfide deposit of Xinjiang province. Sparse disseminated, dense disseminated and massive ores were analyzied, The date of Re-Os isotopic in combination with geology, we think the Re-Os apparent ages ?282+11? Ma with initial ¹⁸⁷Os/¹⁸⁸Os ratio 1.13±0.12 is the time Tula'rgen deposit forming. Seconds, we have study the Re-Os characteristic of Sally Malay, Sparse disseminated and massive ores were analyzied. The Re-Os isochron age ?1856±25?Ma and an initial ration of ¹⁸⁷Os/¹⁸⁸Os?t?= 0.122±0.046, with a MSWD= 25 yield by sparse and massive ores may be the age of Sally Malay Ni-Cu-?PGE? sulfide deposit forming. At the same time, we also study another Ni-Cu-?PGE? sulfide deposit——Copernicus of Australia, the analyzied sample include sparsely, densely disseminated and massive ores, yield a Re-Os isochron age ?1850 ± 17?Ma and an initial ration of ¹⁸⁷Os/¹⁸⁸Os?t?= 0.145 ±0.026, ?1755 ±250?Ma and an initial ration of ¹⁸⁷Os/¹⁸⁸Os?t?=1±1, ?1759±70?Ma and an initial ration of ¹⁸⁷Os/¹⁸⁸Os?1?=0.44±0.15 respectively.In this dissertation, we summarize and study the Re-Os isotope characteristics of Ni-Cu sulphide deposits of domestic and foreign, exploring the universal law of the Re-Os isotope isochron of different species magmatic deposit. In order to obtain geologically meaningful Re-Os age, the type of the ore deposit the type of the ore and the ore-forming process must be took into account. Furthermore, when we interpret the apparent Re-Os age, we should base on the basic principles of economic geology and isotope geochemistry.