河东煤田晚古生代层序地层的碳氧同位素特征

CARBON AND OXYGEN ISOTOPES IN SEQUENCE STRATIGRAPHY OFLATE PALEOZOIC STRATA IN HEDONG COAL FIELD

系统分析了河东煤田上石炭统（Ｃ２）—下二叠统下部（Ｐ１１）４５个碳酸盐岩样品的碳氧同位素在层序中的分布特征，探讨了碳氧同位素应用于层序划分及对比、相对海平面变化研究及晚古生代地层沉积相研究的可能性。研究表明，碳氧同位素在Ｃ２及Ｐ１１的三级层序中的分布特征是不相同的，从ＴＳＴ到ＨＳＴ，在Ｃ２的三级层序中，δ１３Ｃ及δ１８Ｏ不断变重；在Ｐ１１的三级层序中，δ１３Ｃ不断变轻，而δ１８Ｏ不断变重。这种规律在Ｐ１１每个三级层序中均相似，垂向上显示出韵律性。横向上，δ１３Ｃ及Ｚ值总体具有由北向南升高的趋势。碳氧同位素在层序中的分布是受聚煤作用、陆源物质的注入、古气候、沉积环境及时间等控制的。

Through testing 45 carbonate samples collected from PermoCarboniferous caol measures of the Hedong coalfield,the distributions characteristics of carbon and oxygen isotopes in sequences are analyzed,whose feasibilities for sequence subdivision and correlation,as well as for study of relative sea level variations and late Paleozoic facies are also discussed.It is shown that the distributions of carbon and oxygen isotopes in sequences(third order)are different between C2 and P11.In sequences of C2 the values of BX] 13C and 18O varied gradually heavier from TST to HST;in sequences of P11,however,the values of 13C varied lighter from TST to HST,but the values of 18O heavier,both of which presented rhythmicity vertically.Laterally the values of 13C and Z generally present an increasing trend southwards.The distribution of carbon and oxygen isotopes in sequences are controlled by many factors,such as coal accumulation,terrigenous supply,;paleoclimate,depositional environment and geologic time.