四川江油渔洞子下三叠统飞仙关组巨鲕灰岩中疑似蓝细菌及早三叠世疑似蓝细菌的双幕式爆发

二叠纪末海洋生态环境的恶化导致海洋底栖生物的大灭绝及早三叠世蓝细菌的爆发,有关这一时期我国华南蓝细菌化石的报道主要来自早三叠世早期的微生物岩。四川江油渔洞子剖面下三叠统飞仙关组下部巨鲕灰岩中首次发现有丰富的疑似蓝细菌,在种类和结构上与以往所报道的蓝细菌有着明显区别。疑似蓝细菌在巨鲕内和围岩中的富集,表明巨鲕灰岩的成因与疑似蓝细菌的活动有关,与飞仙关组底部微生物岩在成因上有着密切联系,显示早三叠世早期在这一地区发生了疑似蓝细菌的双幕式爆发,同时,暗示着这一地区二叠纪-三叠纪之交至少发生了两次海洋环境恶化及动物灭绝事件。疑似蓝细菌的爆发性生长,对于海洋生态环境的修复和海洋含氧条件的改善,进而为早三叠世末、中三叠世的生物全面复苏、辐射有着重要意义。

Doubtful Cyanobacteria in the Giant Oolitic Limestone of the Lower Triassic Feixianguan Formation from the Yudongzi Section of Jiangyou, Sichuan and Two Episodes of Early Triassic Cyanobacterial Explosions

The disaster event of marine ecological environments at the end-Permian resulted in mass extinction of marine benthic fauna and the explosion of Early Triassic cyanobacteria mainly found from microbialite. The abundant doubtful cyanobacteria are first discovered in the giant oolitic limestone of the lower part of the Feixianguan Formation. Their types and structures are very different from cyanobacteria found in the microbialite at the bottom of the Feixianguan Formation reported before. The gathering of doubtful cyanobacteria in the giant ooids and host rocks implies that the formation of the giant oolitic limestone was closely related to the doubtful cyanobacterial activities. In this case it is similar to the formation of microbialite found at the bottom of the Feixianguan Formation. It can be inferred that two episodes of Early Triassic doubtful cyanobacterial explosions occurred in this region and provide a clue that there were two events of marine ecological environmental deteriorations at least. However, the Early Triassic explosions of cyanobacteria are of benefit to improvement of marine ecological environments and biotic recovery. Therefore, it is significant for the very late Early Triassic and the Middle Triassic overall biotic recovery and radiation.