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新元古界陡山沱组“盖帽”碳酸盐岩中极低碳稳定同位素值被普遍认为是“雪球”地球后甲烷渗漏事件的关键地质证据,δ13Ccarb介于-41‰～-48‰PDB之间,明确指示其成因与甲烷厌氧氧化作用有关.最近,在长阳地区新发现了另外4个显示明显碳同位素负值(δ13Ccarb～-31.89‰PDB)的剖面,并产出大量枝状、扇形、花瓣状重晶石结晶扇,类似于现代海底冷泉区重晶石特征.“盖帽”碳酸盐岩的高分辨率87Sr/86Sr出现异常高值(～0.7186),并与相应层位的极低碳稳定同位素记录之间存在时间上先后关系和成因联系,可能指示甲烷渗漏引起的温室效应造成了陆地化学风化作用的增强和海水87Sr/86Sr比值的增高.因此,华南新元古界陡山沱组“盖帽”碳酸盐岩中保存的极低碳稳定同位素记录、花瓣状重晶石、锶同位素异常正值和帐篷构造、层状裂隙、晶洞等特征性沉积构造,是识别新元古代冰后期和其他地史时期甲烷渗漏事件的综合地质标志.
The extremely low carbon stable isotope values of the Dachanntuo Formation “cap ” carbonate in the Neoproterozoic are generally considered to be the key geological evidence of the methane leak event after the “snowball” Earth. The δ13Ccarb is between -41 ‰ ~ -48 ‰ PDB, indicating that the genesis is related to the anaerobic oxidation of methane.Finally, four more profiles of δ13Ccarb ~ -31.89 ‰ PDB have been found recently in Changyang A large number of dendritic, fan-shaped and petal-shaped barite crystallites are produced, similar to the barite character of the modern seabed cold spring area. "High-resolution 87Sr / 86Sr carbonate rocks show unusually high values (-0.7186 ), And it is related to the time-dependent relationship and genetic relationship with the stable low-carbon stable isotopic records at the corresponding horizon, which may indicate that the greenhouse effect caused by methane leakage has resulted in the enhancement of terrestrial chemical weathering and the 87Sr / 86Sr ratio of seawater Therefore, the records of extremely low carbon stable isotopes, petal-like barites, positive anomalies of strontium isotopes, tectonic tectonics, stratigraphic fissures in the Dachanntuo Formation, Geode deposits and other characteristic sedimentary structures, is to identify Neoproterozoic ice Comprehensive geological signs of methane leakage and other events of the history of the period.