Search

The evolution of the global sulfur isotope curve was plotted based on the δ 34S values of evaporates resultant from oceanic evaporation. In the long period of geological history the δ 34S values showed obvious peaks for three times during the process of ancient oceans’ sulfur isotope evolution, namely the Early Cambrian (+30‰), the Late Devonian (+25‰) and the Permian-Triassic transition interval (+17‰), but the causes of the abnormal rise of sulfur isotopic values during the geological period are still in question. In this paper, 18 samples collected from a large Devonian barite deposit from Zhenning County were analyzed to determine their δ 34S values, revealing that the 18 samples have very high δ 34S values (δ 34S=41.88‰–+68.39‰), with an average close to 56.30‰, which are higher than the isotopic values of contemporary sulfates (+17‰–+25‰). A comparative analysis was conducted of the emerging of high δ 34S barite deposits (from Cambrian and Devonian) and the δ 34S variation curves of the ancient oceans. The results indicate that the time when the obvious peaks of δ 34S values appeared and the time of massive sedimentation of high δ 34S barite deposits are very close to each other, which, in our opinion, is not a coincidence. There may exist some correlations between the sulfur isotope evolution of ancient oceans during the diverse periods of geological history and the massive sedimentation of high δ 34S barite deposits. Therefore, it is inferred that perhaps it was the massive sedimentation of high δ 34S barites that caused the sharp rise of δ 34S values in a short period of time. [ABSTRACT FROM AUTHOR]

With the continuous development of gold ore prospecting and exploration in recent years a new type of micro-disseminated gold deposits have been found in the regions of Southwest Guizhou Province and Northwest Guangxi Zhuang Autonomous Region, with the orebodies directly occurring in diabase or in the contact zone between diabase and strata. The orebodies are strictly controlled by fault structures. The discovery of this type of gold deposits has brought about new prospects for gold ore prospecting in the Yunnan-Guizhou-Guangxi Golden Triangle region. From the preliminary analysis of the geological characteristics of the Qiaoxiang gold deposit in Wangmo County, in combination with the results of research work in the adjacent areas in recent years, this paper roughly described the geological characteristics and metallogenic conditions of this type of gold ore deposits with an attempt to make more and more geologists pay enough attention to this type of gold ore deposits, so as to promote gold ore prospecting in Guizhou Province to develop toward a variety of types of gold deposits in all round way. [ABSTRACT FROM AUTHOR]