Sulfur Isotope Study of Precambrian Basement and Mesozoic Intrusive Rocks in the Southwestern Part of Ryeongnam Massif, Korea |
| |
Authors: | Chung-Han Yoon Cheong-Bin Kim Hyo-Jae Lee Hidehiko Shimazaki |
| |
Affiliation: | Department of Mineral and Energy Resource, College of Engineering, Chonnam National University, 300 Yongbongdong, Buk-gu, Gwangju City 500–757, Korea [e-mail: ];School of Earth and Environmental Sciences, Seoul National University, Seoul 151–742, Korea;Graduate School of Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju City 500–757, Korea;Key Laboratory of Mineral Resources Exploration, Chinese Academy of Sciences, Beijing 100101, China |
| |
Abstract: | Abstract. Isotope composition of whole rock sulfur has been measured on 14 schists, 10 gneisses, 7 gabbroids, 7 granitoids and 2 sedimentary rocks, with of 9 sulfide (pyrite) sulfurs in gabbros and granitoids, from the southwestern part of the Ryeongnam Massif, Korea. The δ34S values of schists range from -4.6 to +6.1 % (average +0.9 %), those of gneisses from -4.0 to +0.8 % (-1.9%), those of gabbroids from -2.3 to +3.7 % (+1.0 %), and those of granitoids from -5.9 to +3.2 % (-1.9 %). The δ34S values of pyrite separated from gabbros and granitoids show rather heavier values ranging from +3.1 to +9.4 % with an average of+5.8%. Though the δ34S values of whole rock sulfur give wide range of -5.9 to +6.1 %, the average of about -0.5 % is close to the mantle value. The granitoids sampled at the central parts of intrusive bodies or at the contacts with other plutonic rocks tend to show positive values, while those sampled near the boundary with basement rocks such as granitic gneiss and por-phyroblastic gneiss show negative values. Though the reason of this tendency is not clear at present, the δ34S values of some granitoids in this area seem to represent possible influence by the assimilation of country rocks, particularly of gneisses. Average isotopic compositions of ore sulfur from individual metal deposits in the studied area are summarized to have a range of+1.0 to +7.8 % with an average value of+3.2 %. The values are consistent with the previous finding that the ore sulfur isotopic values of the Ryeongnam Massif are the lowest among the four tectonic belts in Korea; Gyeonggi Massif, Ogcheon Belt, Ryeongnam Massif, and Gyeongsang Basin. This feature may reflect the isotopic compositions of plutonic rocks and basements in this area, which are characterized by relatively low values around zero permil. |
| |
Keywords: | sulfur isotope basement granitoid rock sulfur ore sulfur Ryeongnam Massif Korea |
|
|