PATTERNS IN MICROBIALITES THROUGHOUT GEOLOGIC TIME: IS THE PRESENT REALLY THE KEY TO THE PAST?
While there are a variety of microbialite morphologies, most can be classified into three main categories based on their macroscopic, internal structure (mesostructure): (1) Stromatolites, which have a laminated fabric, (2) Thrombolites, which have a clotted fabric, and (3) Leolites, which have an undifferentiated fabric.
The record of both stromatolites and thrombolites throughout geologic time is prominent, however, interpreting mechanisms of microbialite formation within the fossil record is challenging due to loss of organic matter, microbial degradation, and diagenesis. Due to our inability to discern the specifics of genesis from fossil specimens, modern microbialites are often used as a proxy to understand Earth's earliest life.
The formation of microbialites in a variety of environmental conditions across the Earth makes these attempts at comparing the recent structures to the ancient more difficult. Fluctuations in sea chemistry, mineralogy, and biotic communities further complicates matters.
Correlation between microstructure, macrostructure, and environmental conditions is essential for proxy work to be relevant. Microbialite fabrics have not yet been correlated with specific environmental conditions. In addition, while macrostructure may persist after diagenesis, microstructure is often heavily altered, complicating comparison between ancient and modern specimens.
This research analyzes data from both fossil and modern microbialites and associated environmental parameters to determine if sufficient similarities exist to allow use of modern microbialites as a proxy for specimens from the fossil record.