Microbial mat controls on infaunal communities and fabric development in modern marine microbialites

Lidya Tarhan
University of California-Riverside, Department of Earth Sciences Riverside, California, USA
[email protected]

Microbialites are the most abundant macrofossils of the Precambrian. Decline in microbialite abundance and diversity during the terminal Proterozoic and early Phanerozoic is commonly attributed to the concurrent radiation of burrowing and grazing metazoans. Similarly, the apparent resurgence of microbialites in the wake of Paleozoic and Mesozoic mass extinctions is frequently linked to drastic declines in the diversity and abundance of metazoan reefal communities. However, it has become increasing clear that microbialites are relatively common in modern shallow, normal marine carbonate environments—foremost the Bahamas. Moreover, I have found that modern marine Bahamian microbialites can also host dense and diverse communities of infaunal metazoans. In order to identify the predominant control upon infaunal community dynamics, I will systematically characterize the relationship between macro- and micro-sedimentary dynamics, the ecology and chemistry of framework-building cyanobacteria, microbialite fabric and infaunal abundance and diversity.

The manner in which metazoan diversity and abundance influence the formation, early diagenesis and preservation of modern microbialite fabrics holds important implications for our understanding of both modern and ancient microbialites. Moreover, these findings necessitate that we rethink prevalent interpretations attributing Phanerozoic declines and fluctuations of microbialites to metazoan-mediated exclusion.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects