古地理学报2012，Vol.14Issue(1)：117-124,8.
鄂尔多斯奥陶系碳酸盐岩碳氧同位素特征及其意义
Characteristics of carbon and oxygen isotopes of the Ordovician carbonate rocks in Ordos and their implication
摘要
Abstract
The Ordos has gigantically thick Paleozoic marine strata. The carbon and oxygen isotopes of the Ordovician carbonate rocks in the Ordos are less modified by post-depositional diagenesis, and thus provide helpful insights into the original ocean. The δ13C values of the Ordovician carbonate rocks in the Ordos range from - 7. 30‰ to 2. 26‰ with a mean value of - 0. 30‰ and the δ18O varies between -13. 14‰ and -1.94‰, averaging at -6. 38‰, which indicate the carbon and oxygen isotopes of the Ordovician in the Ordos are comparable to those of the global Ordovician. Spatially, the δ13C shows a decreasing trend, indicating shoaling in water-depth from the western margin of the Ordos, to the southern margin and then to the eastern margin. Temporally, the S C gradually increases, showing that sea level rose from the Early to the Late Ordovician, with a significant positive excursion between the Middle and Late Ordovician that is indicated by increase in mean δ13C value from -0. 36‰ in the Majiagou Formation to 0. 15‰ in the Pingliang Formation and then to 0. 68‰ in the Beiguoshan Formation. Sea level change suggested by carbon isotope distribution is consistent with the evolution of sedimentary facies. The positive excursion of carbon isotopes in the Middle and Late Ordovician in the Ordos indicates relative high productivity and organic carbon burial, which is of important petroleum geological significance, reflecting the Pingliang Formation, Wulalike Formation and Beiguoshan Formation in the southwestern margin as the most important and efficient hydrocarbon source rocks of the Lower Paleozoic in the Ordos.关键词
碳氧同位素/古环境/石油地质/奥陶系/鄂尔多斯Key words
carbon and oxygen isotopes/ paleoenvironment/ petroleum geology/ Ordovician/Ordos分类
天文与地球科学引用本文复制引用
陈强,张慧元,李文厚,郝松立,刘卓..鄂尔多斯奥陶系碳酸盐岩碳氧同位素特征及其意义[J].古地理学报,2012,14(1):117-124,8.基金项目
国家科技重大专题(编号:2008ZX05005-004-007HZ)资助 （编号:2008ZX05005-004-007HZ）
