EAPS Special Lecture
Dr. Rowan Martindale
Organismic and Evolutionary Biology
"Paleoecology of Upper Triassic reefs and the collapse of the carbonate system at the Triassic-Jurassic, a potential ocean acidification event"
Friday, April 5, 2013
4:00 to 5:00 p.m.
Building 54, Room 915
The Triassic, 251-201.3 Ma, is considered to be the period in Earth history when modern-style reefs, constructed by scleractinian corals (modern stony corals) evolved. Modern corals began calcifying in the Middle Triassic and reefs built by these newly evolved corals and hypercalcified sponges proliferated through the Late Triassic (235–201.3 Ma). Four Upper Triassic reef complexes from North America exhibit strong latitudinal trends in reef ecology. Corals built the southernmost (tropical paleolatitudes) reefs, but the more northern reefs (subtropical to temperate paleolatitudes) are microbial reefs. In northeast Panthalassa cool, nutrient-rich waters swept south along the western North America borderlands and this thermal gradient created a strong north-south differentiation in reef ecology (cool-water microbial reefs to warm-water coral reefs). The cool-water reef model presents a new paradigm of Triassic reef ecology, which is strikingly different from the warm-water models developed for the Tethyan coral reefs of the Alps.
Following their proliferation in the Late Triassic, reefs and other marine communities collapsed at the end of the Triassic. The Triassic–Jurassic transition is not only one of the largest mass extinctions but has also been hypothesized to be an ocean acidification event driven by the eruption of the Central Atlantic Magmatic Province (CAMP) flood basalts and the rapidly release of massive amounts of volcanic volatiles (e.g. CO2 and SO2). There is evidence for a gap in carbonate sedimentation across the T–J boundary interval consistent with ocean acidification (dissolution of sediments or lack of precipitation) and the end-Triassic extinction is particularly selective against pH-sensitive organisms and ecosystems, such as corals and coral reefs. These observations suggest that ocean acidification, if not the key cause, was certainly an important extinction factor.
Recently, Rowan has begun work on a similar interval, the Toarcian (Early Jurassic, ~183 Ma), which is another extinction, reef collapse, and anoxic event that is thought to have been caused by the eruption of another Large Igneous Province (Karoo-Ferrar). This work on Early Jurassic shales from North America and reefs from Italy and Morocco will elucidate whether ocean acidification occurred during the Toarcian.
Refreshments precede the talk in Building 54, Room 923.
All are welcome.
Talk hosted by Prof. Sam Bowring.
Questions: jtaylor [at] mit [dot] edu