CYCLOSTRATIGRAPHY OF MICROBIALITES IN BACON COVE, NEWFOUNDLAND, CANADA AND THEIR IMPLICATION FOR DEPOSITIONAL ENVIRONMENTS AND PALEOCURRENTS OF THE LOWER CAMBRIAN

In Bacon Cove, Newfoundland, Canada, rhythmic microbialites in siliciclastic–carbonatic sediments of the pre-trilobitic Bonavista and Smith Point Formation are exposed. They were deposited on the former microcontinent Avalonia during the Fortunian and Series Two in the early Cambrian. The rhythmic microbialites were scaled and statistically evaluated after a detailed bed-by-bed examination of the succession. Three, each other overlapping, cycles have been interpreted from the statistically evaluation and the lithologies. The cycles were in part probably induced by Milankovic cycles.

The Bonavista Formation also contains up to five percent hyoliths in part as shell debris, in part articulated oriented. With the latter, a paleocurrent analysis has been carried out and two different paleocurrents have been interpreted.

Based on the interaction of the microbialites with the hyoliths and the lithologies the depositional environment has been interpreted assuming that the appearance of the microbialites depends on the interaction of current, nutrient input and climate. This enables conclusions about sedimentary input, depth of the photic zone and current.