贵州紫云羊场石炭—二叠纪之交的重力流沉积及其意义

The uppermost Carboniferous-lower Lower Permian gravity flow sediments in Yangchang, Ziyun of Guizhou and their significance

贵州南部上石炭—下二叠统地层发育,沉积连续,各门类化石丰富,是石炭—二叠系界线地层研究的重点地区。各门类古生物由于生态的差异,通常不在一个剖面上共生,特别是和牙形刺在各剖面上成互为消长关系。在台地浅水区,相当丰富而牙形刺罕见;在盆地深水区,牙形刺丰富,但无原地生活的,所产的少量也为重力流带入;

Three types of gravity flows (debris flow, grain flow, and turbidity flow) are developed in the uppermost Carboniferous-lower Lower Permian of Yangchang, Ziyun of Guizhou.Of them, the turbidite de-posits contain uncomplete Bouma cycles.The debris flow sheets have a wide horizontal extent, one of which even extended for more than 10 km.Such a depositional character suggests a trough margin.Gravity flow sediments are excellent units for preservcition of fossils.Some fossils wrapped up in debris are regarded as 'packed form' by the author, and others preserved in matrix between debris are regarded as 'free form.' The former had been petrified in shallow water before they were transported into deep water by gravity flows, but the time-interval between deposition and redeposition of the fossils is so short that it may be neglected.Therefore.the special mixed fauna here would provide a reliable correlation between several fossil groups and a useful evidence for the establishment of carboniferous-Permian boundary