CALCIMICROBES AND ARCHAEOCYATHS IN EARLY CAMBRIAN REEFS: WHAT DO WE REALLY KNOW ABOUT THEIR RELATIONSHIP?

The relationship between calcimicrobes and archaeocyaths is not well understood. It is common knowledge that where archaeocyathan reefs proliferate, calcimicrobes, such as Renalcis and Epiphyton are present. Researchers debate on whether or not this relationship is symbiotic, and both arguments are supported by excellent data. Difficulty in understanding the ecology and relationship of calcimicrobes stems from their ubiquitous nature, for calcimicrobes belong to several of the Fagerstrom (1988; 1991) guilds, being encrusters, binders, and builders of reefs. For example, Renalcis is often found encrusting the outer walls of archaeocyaths, lining primary cavities, and forming isolated clots, all within the same reef.

Four reef localities illustrate the relationship between archaeocyaths and calcimicrobes. These are the Lower Poleta Formation, Xiannudong Formation (both Nevadella zone), upper part of the Harkless Formation, and the Tianheban Formation (both Bonnia-Olenellus zone). Within the Poleta and Tianheban, both Epiphyton and Renalcis are present. The Tianheban also contains Girvanella and Proaulopora, while the Harkless only contains Renalcis. The Xiannudong Formation contains Renalcis and Girvanella. Stromatolites in the Xiannudong contain no preserved microbes. Each of these formations has microbial and/or archaeocyathan-microbial reefs that formed in a variety of moderate to high-energy regimes.

This paper is designed to combine the data that is known on calcimicrobes with samples from the above described reefs. It is a look into the association among the differing microbes, archaeocyaths, and their paleoenvironments in hopes of better understanding their close relationship.