河北-铅锌矿床的硫同位素研究

本文研究的铅锌矿床在大地构造上位于华北地台燕山沉降带中部马兰峪背斜的北翼。北翼主要出露太古界和上元古界地层。

SULFUR ISOTOPE STUDY OF THE SPHALERITE-GALENA ORE DEPOSIT IN HEBEI PROVINCE

The sphalerite-galena ore deposit in Hebei Province, is a stratabound sulphide ore deposit of multiple metals occureed in carbonate rocks in the lower part of the third member of the Gaoyuzhuang Formation, Changcheng System, Upper Proterozoic Group. In this paper, we attempt to discuss the sulfur origin in the deposit as well as the cause of sulfur isotopic fractionation and to provide more evidences for interpretation of ore formation.In this paper the results of determination of sulfur isotope ratios of 52 sulfide minerals from the deposit are reported. The results are as follows:1. δS³⁴ values of various sulfide minerals in the deposit range from -10 to +24.1 per mil. δS³⁴ of pyrite have a range from -10.0 to +24.1 per mil, δS³⁴ of sphalerit range from -3.2 to +15.3 per mil, δS³⁴ of galena range from -8.9 to +6.6 per mil.2. The δS³⁴ values of the stratified pyrite are usually greater than the veinform pyrite.3. The δS³⁴ values of the stratified pyrite are related to its occurance as well as the nature of the country rock. For instance, the δS³⁴ values of the lamellar and striped pyrites in black shale range from +10.1 to +24.1 per mil. The δS³⁴ values of the disseminated and massive pyrites in dolomits range from -5 to +3.5 per mil.4. The δS³⁴ values of the various veinform sulfide minerals are different. The δS³⁴ values of the sphalerites in the veinlet, in most instances, range from -3.2 to +5.1 per mil and occasionly from +10.6 to +15.3 per mil. The δS³⁴ values of the galena in veinlet, in many instances, range from -8.9 to -4.9 per mil and occasionly from +4.9 to +6.6 per mil. The δS³⁴ values of the pyrites in the veinlet mainly range from -4.9 to +5.7 per mil and occasionaly are near -9 per mil.5. The total variation tendency of δS³⁴ values of the veinform sulfide minerals in the various country rocks are as same as the stratifide minerals. For instance, the δS³⁴ values of the stratifide sulfide minerals in black shale are greater than that in dolomites and the δS³⁴ values of the veinform sulfide minerals in black shale are greater than that in dolomites as well.Based upon distribution of the sulfur isotope of the deposit mentioned above, the following conclusions can be reached: the dispersion of the sulfur isotopic composition of stratified pyrites indicates that its sulfur source is the biogenetic H₂S produced by the bacterial reduction of ancient ocean water sulfate. It is attributed to the difference of the environment of ores formation. The δS³⁴ values of the lamellar pyrites in the black shale are greater than the disseminated and massive pyrites in dolomites. The veinform sulfide formation was related to leaching of subsurface thermal water to sta-tified sulfide minerals deposited earlier.