摘要 早三叠世贵阳花溪地区大冶组中段Phycosiphon数量丰富、保存完整, 为研究其生态行为习性和形态结构提供了良好材料。大冶组Phycosiphon潜穴系统由“U”型叶片状觅食迹和线形爬行迹构成; 对61个样品中的267个“U”叶片的宽、高和边缘管直径统计分析表明, “U”型叶片宽、高比一般在50%-60%之间, 边缘管直径和叶片高之比在12%-18%之间, 并结合线性相关分析认为Phycosiphon造迹生物大小与叶片大小存在一定的关系; 通过对Phycosiphon造迹生物行为习性的分析, 认为叶片的凹曲方向可以指示造迹生物的觅食方向。在形态上, “U”型觅食迹和线形爬行迹可以构成鹿角状、团状、不规则状以及链状四种组合类型。鹿角状和团状多形成于浊流前, 指示低能静水环境; 不规则状一般形成于浊流后, 指示沉积速率大和相对高能的水体环境; 而链状在这两种环境中都有发育, 体现了Phycosiphon造迹生物随机性觅食的特点。早三叠世研究区处于浅海碳酸盐台地斜坡地带, 浊流频发, 整体处于贫氧、低能环境, Phycosiphon在大冶组二段的发育是P-T事件后“错时相”特征之一。
Abstract Phycosiphon is abundant and well preserved in the middle portion of Daye Formation in Huaxi district of Guiyang in Early Triassic, which provides good materials for studying its ecological behavior and morphological structure. The Phycosiphon burrow system of Daye Formation is composed of "U"-shaped leaf-shaped pascichnia and linear repichnia. Statistical analysis of width, height and edge tube diameter of 267 "U" leaves in 61 samples shows that the ratio of width to height of "U" leaves ranges generally from 50% to 60%, and the ratio of edge tube diameter to leaf height ranges from 12% to 18%. Combined with linear correlation analysis, it is considered that there is a certain relationship between Phycosiphon trace maker size and leaf size; through the analysis on the behavior of Phycosiphon trace makers, it is considered that the concave direction of leaves can indicate the foraging direction of Phycosiphon trace makers. In morphology, "U"-shaped pascichnia and linear repichnia can form 4 combined types: antler- shape, mass-shape, irregular-shape and chain-shape. Antler- shape and mass-shape are mostly formed in front of turbidity flow, indicating low-energy still water environment; irregular-shape is generally formed after turbidity current, indicating water environment with high deposition rate and relatively high energy; However, chain-shape develops in both environments, which reflects the random foraging characteristics of Phycosiphon trace makers. The early Triassic study area is located in the slope of shallow sea peri-platform slope, with frequent turbidity current, and the whole area is in an oxygen-poor and low-energy environment. The development of Phycosiphon in the second member of Daye Formation is one of the characteristics of "anachronistic facies" after P-T event.