豫西登封地区寒武系张夏组中部生物扰动构造及其地质意义

掘穴生物作为生态系统工程的建造者，其对沉积物进行的改造直接影响了沉积物的物理化学性质，进而影响了底栖生态系统。豫西登封地区寒武系苗岭统张夏组中部薄层微晶灰岩中发育大量的生物扰动构造，利用地球生物学、古生物学和生物扰动指数等方法，探讨了生物扰动构造的形成环境及其对沉积物的影响。研究表明，研究区张夏组中部生物扰动构造特征多为扰动边界模糊不清，生物扰动指数（BI）为2 ~ 5，说明该沉积期食物充足，氧气含量高。此外，在生物扰动中识别出3种遗迹化石：Thalassinoides bacae，Planolites isp.和Rhizocorallium isp.，说明生物扰动构造为多种生物造迹形成的。依据寒武系苗岭统张夏组中部的遗迹化石以及沉积特征，可知其整体处于偶尔受到风暴影响的滩间局限台地环境。

Bioturbation Structure and Their Geological Implications from Zhangxia Formation of Cambrian in Dengfeng Area,Western Henan Province

Burrowing animals as the builders of ecosystem engineering, their bioturbation structures affect the physical and chemical properies of sediments, which are important for the benthic ecosystems. Abundant of bioturbation structures are preserved in the laminated microcrystalline limestone in the middle part of the Cambrian Miaolingian Zhangxia Formation, Dengfeng area, western Henan Province. In this paper, the methods of geobiology, paleontology and bioturbation index (BI) are used to investigate the depositional environment of the bioturbation structures and their influence on sediments. Most of bioturbation structures have blurred boundaries. The bioturbation index is 2-5, indicating sufficient food supply and high oxygen content in the sediments during the deposition period. In addition, three types of trace fossils are recognized:Thalassinoides bacae, Planolites isp. and Rhizocorallium isp, indicate that the bioturbation sturctures are created by more than one trace maker. The research on the trace fossils and sedimentary characteristics of the Zhangxia Formation indicates a restricted platform environment between oolitic banks that occasionally affected by storms.