| 云南腾冲地块北部空树河组一个菱铁矿结核中的C、O同位素变化特征 |
| 修订日期：2001-07-18 |
| 关键词:carbon isotope oxygen isotope concretion western Yunnan |
| 基金项目:国家自然科学基金 ( 40 0 72 0 65 )，中国地质调查局重点基础地质研究项目“中国花岗岩重大地质问题研究”和西北大学大陆动力学教育部重点实验室开放基金资助 |
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| 摘要: |
| Carbon and Oxygen Isotope Variation in a Siderite Concretion from Kongshuhe Formation, Western Yunnan |
| Siderite concretions were found in black lutites near the top of the Kongshuhe Formation, which represents a Permo Carboniferous Gondwana glacial to post glacial sequence in the northern part of the Tengchong block, western Yunnan. A concretion was cut through the center, and nine samples were extracted from the cut surface with the help of a dentist's drill. Isotopic investigation shows that δ 13 C decreases outwards steadily from -8.09‰ to -16.12‰ except for the outermost sample (-15.39 ‰), and that δ 18 O increases from -10.64‰ in the center to about 0‰ on the margin. Such a δ 13 C variation implies that this siderite concretion might have been formed in the sulphate reduction zone. For the interpretation of δ 18 O variation, it is assumed that 18 O depleted meteoric water was probably involved at the time when the concretion started to precipitate, and that the oxygen isotope composition of the pore water approached gradually the value of normal ocean water (0‰) with the increase of the burial depth. |
| JIN Xiao-chi.2002.Carbon and Oxygen Isotope Variation in a Siderite Concretion from Kongshuhe Formation, Western Yunnan[J].Acta Geoscientica Sinica,23(1):37-41. |
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