介绍和评述Chondrites的基本特征和流行的成因解释 ,记述最近发现于美国犹他州中西部北美下 中奥陶统之交层型剖面上的Chondrites遗迹组构的不寻常特征和属性 :细小的Chondrites被所有与之共生的遗迹化石交切 ,形成于水与沉积物界面附近缺氧的早期软底质中 ,Chondrites是形成最早和最浅的遗迹阶层。流行的遗迹相和遗迹阶层模式的不足是 :前者在操作上 ,简单地将遗迹化石及其组合处理为同沉积或准同沉积的物理沉积构造 ,忽略了造迹活动的多阶段和多阶层的特点 ;后者的资料基础仅依据中生代以来的地层记录 ,对重大生物 环境事件和造迹生物生态习性演化对遗迹阶层形成和分布的影响注重不够。指出Chondrites的阶层分布和对古氧相的示踪在古生代与中生代有重要差别

Basic characteristics and prevailing genetic models of Chondrites have been introduced and commented. Unusual features of Chondrites from the Lower Middle Ordovician transition have been reported in the west central Utah, USA. They include that tiny Chondrites were cut by other trace fossils associated with them and formed in softground,and that Chondrites were the earliest or shal lowest tiering in the complex ichnofabrics. In existing ichnofacies model trace making courses with ulti stages and ulti tiering are not stressed. Existing ichno tiering models are based mainly on the Mesozoic Cenozoic data. The reported data show that tiering distributions of Chondrites are different in Palaeozoic and Mesozoic Cenozoic. It seems that Palaeozoic tiny Chondrites can be formed in shallowest and middle tierings.

Q911

国家自然科学基金 (Nos.40 0 72 0 41，49472 0 86)，科技部攀登计划专项SSER项目，美国科学基金项目联合资助课题