Peter Tierney

For most people, the word "reef" brings forth colorful images of densely-packed coral mounds, teeming with diverse life. When 19th to mid-20th century paleontologists found abundant corals or sponges in outcrop, they too approached them with the same search image. However, reef construction has varied tremendously through time, in scale, morphology and skeletal contribution. Unsurprisingly, early workers would often present too simple a view of how reefs were being constructed and how they contributed to surrounding sediment and local ecology.

 

Rock description has come a long way since then, but the translation of rock fabric to in-life structure, and the potential impacts of physical structures on life, have generally been ignored in reef environments.

 

I am interested in that translation, unpacking what we see in the rock record, and relating those structures to environmental heterogeneity, community evolution, and niche partitioning. To best study this, I focus primarily upon the transition from microbial to metazoan-dominated reefs during the Ordovician. This is an ideal system in which to examine how structure affects community. Reefs are increasing in physical heterogeneity with the advent of novel metazoan reef builders, and with the lack of significant bioeroders, and the presence of rapid inorganic cementation, structures are often preserved in situ.

 

In addition to studying this transition, I am interested in several other large questions, including, but not limited to:

 

• What drives rapid speciation in the reef system through deep time?

• At what scales can we readily identify heterogeneity in framework carbonates? How does what we see reflect living structure?

• To what extent to reef dwellers and builders exhibit different sensitivities to purturbation? 

• Do corresponding reef structures encourage similar community structures through deep time?

 

My thesis work touches upon each of these questions.Through my work, I hope to gain insight into the sedimentary development of bioherms of highly variable construction.  Moreover, I hope to gain a deeper understanding of how the reef system influences large scale evolutionary trends through deep time.