The Discriminating Application Of Sulfur Isotope In The Cause Of Geochemical Anormality

The Genesis of geochemical anomaly, one of the key factor for the evaluation of its exploration potential, minerlization type, and deployment to prospecting and exploration work, has not been taken into account in the past geochemical exploration. Based on the method and principle of the tracing in the source of mineralization material from the stable isotope, we use the sulfur isotopic indexes from Wunugetushan, Kenshan, Bainaimiao,Inner Mongolia, and Chengmenshan area in Jiangxi, and try to use the characteristics of sulfur isotopic composition (δ³⁴S) to determine the causes of geochemical anomalies. Further more, some expected results have been obtained.The sulfur isotopic analysis shows that the pyrite from Wunugetushan area haveδ³⁴S values that range between -1.3 and +3.2‰, it indicate that the sulfur from the lower crust. Theδ³⁴S values abtained from Bainaimiao area have a range between -2.8 and +13.8‰, and most of them are negatives, which indicate that the sulfur of this area had suffered the mixing of crustal and marine pollution.Chengmenshan area haveδ³⁴S values that range between -0.3 and +3.2‰, it indicate that the sulfur from the lower crust or upper mantle. Theδ³⁴S values abtainede from Kenshan area have a range between +3.2 and +4.3‰, it indicate that the sulfur source is lower crust and has suffered the influence of hydrothermal fluids activities of the later stage.By comparing the characteristics of sulfur isotopic composition in Cu mineralization and Cu abnormality from one region with others, we have found that the related source of sulfur in element in Cu mineralization and Cu abnormality are primarily unanimous in earch testing region. For a deposit or abnormality which was formed in the same geological processes, the sulfur isotopic composition of symbiotic are particularly same, which indicated that the mineralization material and abnormality materal were from the same source area. This provides a basis for using the sulfur isotope composition to determine the causes of geochemical anomalies, and it indicates that using sulfur isotopic composition to determine the causes of geochemical anomalies is feasible. In the Wunugetu Moutain region, some researches showed that the metallogenic material of the orebodies and mineralized wallrocks came from the lower crust, as well as the composition of anomalies in the external wallrocks. In another region-Bainaimiao, the similar situation occurred that the sulfurs from the metallogenic material of the orebodies and mineralized wallrocks and the composition of the anomalies in the external wallrocks was resulted from the deep section of the crust, while they were contaminated by the crust cycle and the seal water. In the last two test region also showed the similar situation.In the Chenmenshan region, the metallogenic material of the orebodies and mineralized wallrocks came from the lower crust or the upper mantle, as well as the composition of anomalies in the external wallrocks.In the Kenshan test region, the composition of anomalies, which was influenced by the hydrothermal of later stage, came from the lower crust.The result shows that sulfur isotopic compositon in Kenshan area are significantly different from Wunugetushan, Bainaimiao and Chengmenshan area. According to the characteristics of sulfur isotopic composition, mineralogy and geochemistry in these area, and inferred that such as Cu multi-element anomalies are formed by the late hydrothermal. Furtherly, the area does not have the conditions for the formation of porphyry deposit; in addition, some prewiews researchs show that the Cu abnormities are relatd to porphyry mineralization. Geological prospecting and deployment for these abnormities should be carried out around the hydrothermal deposit; this will provide the basis for the next exploration.Based on the characteristics of sulfur isotope composition, it can be used in mineral exploration as a indicator applied to determine the causes of geochemical anomalies. More over, it provides the basis for evaluating the prospect of its mineralization, and the guidance for the geological survey work in anormaly area. Not only it expands the applications of sulfur isotopes in geology studies, but also provides a favorable evidence for evaluating the prospects of the geochemical anomalies. Besides that, it obviously improve the prospect results and the level of basic theory of geochemical exploration.