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广西隆安剖面和巴平剖面下石炭亚系碳酸盐岩稳定碳同位素的研究表明,早石炭亚纪孤立台地相和深水斜坡相碳酸盐岩碳同位素受早期淡水及后期埋藏成岩作用影响较小,基本上保存了正常海水碳同位素演化特征.华南地区早石炭亚纪的δ13C值表现出3个明显的正向偏移.经牙形石生物地层对比,第1次明显的δ13C正向偏移发生在杜内阶Siphonodella isosticha-Upper Siphonodella crenulata带中部,偏移量为4.19‰;第2次明显的正向偏移发生在杜内阶/维宪阶之交,偏移量为4.65‰;第3次明显的δ13C正向偏移发生在谢尔普霍夫阶Gnathodus bollandensis带底部,偏移量可达2.23‰.这3个明显的碳同位素正向偏移在全球范围内均可以得到很好的对比,与华南地区及全球海平面下降一致,反映了早石炭亚纪有机质大量埋藏、大气CO2分压的下降以及晚古生代的冰川作用.
Carbonate stable carbon isotopes of the Carboniferous subfacies in the Longan and Baiping sections of Guangxi suggest that the carbon isotope of the carbonate platform in the early Carboniferous sub-platform and the deep-water slope facies was less affected by the early fresh water and later burial diagenesis , Which basically preserved the evolutionary characteristics of carbon isotopes in normal seawater.The δ13C values of Early Carboniferous in South China show three obvious positive deviations.The first significant δ13C positive deviations Occurred in the middle of the Siphonodella isosticha-Upper Siphonodella crenulata zone in the Dune, with an offset of 4.19 ‰. The second significant forward offset occurred at the turn of the Dune / Uygur order with an offset of 4.65 ‰. Three significant δ13C forward shifts occurred at the bottom of the Sernupphoff Gnathodus bollandensis zone, with an offset of up to 2.23 ‰. These three significant carbon isotope forward shifts are well comparable globally , Which is consistent with the declination of sea level in South China and the world. It reflects the massive burial of organic matter in the Early Carboniferous, the decrease of atmospheric CO2 partial pressure, and the glacial effect of Late Paleozoic.