二叠纪末生物大灭绝后Skolithos遗迹化石的古环境意义:以豫西和尚沟组为例*

豫西地区下三叠统遗迹化石记录了二叠纪—三叠纪之交生物大灭绝事件(PTME)后遗迹群落由残存向复苏的演变,其中Skolithos以垂直或高角度倾斜于岩层面、被动充填为典型特征,广泛保存于下三叠统和尚沟组。文中以登封、宜阳地区下三叠统和尚沟组保存良好的Skolithos遗迹化石为研究对象,从宏观和微观不同尺度分析Skolithos遗迹属。基于遗迹化石和生物扰动记录反映的生物运动能力、觅食策略、生物与沉积物相互作用的方式、生物改造沉积物的方式,构建出豫西地区和尚沟组生态空间占据和生态系统工程三维空间模式图;在此基础上,进一步分析Skolithos的古环境意义,探讨Skolithos所指示的高生态压力。研究结果表明,经历过PTME事件后的Skolithos遗迹化石主要受到高温、干热气候以及巨型季风等高生态压力的影响,并在此影响下形成机会主义遗迹组合,在曲流河、滨浅湖环境中广泛发育。该成果可为豫西地区下三叠统的陆相沉积环境以及古生态背景研究提供参考依据。

Paleoenvironmental significance of ichnogenus Skolithos in the aftermath of the end-Permian mass extinction: a case study of the Lower Triassic Heshanggou Formation in western Henan Province

The Lower Triassic ichnofossils in the western Henan record the evolution of trace-maker communities from remnant to recovery after the Permian-Triassic mass extinction(PTME). Skolithos is characterized by vertical or high angle inclination to the rock layer,and is widely preserved in the Lower Triassic Heshanggou Formation. Macroscopic and microscopic characteristics of Skolithos were studied on abundant,well-developed Skolithos specimens collected from the Heshanggou Formation in Dengfeng and Yiyang areas.We conducted a three dimensional occupation cubes of ecospace utilization and ecosystem engineering by analyzing the motility,feeding strategy,the interaction between organisms and substrate, and the way of biological modification of sediments. We also analyzed the paleoenvironmental significance of Skolithos and explored the high environmental pressure indicated by Skolithos ichnofossils. The results show that Skolithos is mainly affected by high environmental pressures such as high temperatures,dry and hot climate and giant monsoon in the early stage of recovery. As an opportunistic ichnogenus, Skolithos was widely developed in meandering river and shallow lacustrine deposits. The above results may provide a reference for the study of continental sedimentary environment and paleoecological background of the Lower Triassic in the western Henan.