Reports: AC2
47576-AC2 A Refined Chronology of Late Eocene to Late Oligocene Coral Reefs: Implications for Coral Calcification Under a Regime of Declining Atmospheric Carbon Dioxide and Changing Ocean Chemistry
Field Expedition & Sample Collection: The graduate student supported by this award, Francois Paquay, has traveled to multiple Eocene- Oligocene sedimentary sections in Italy. With the assistance of Francesca Bossalini, Universita di Modena, Italy he has sampled several of these sections. Upon his return to Hawaii, a subset of the most promising samples, those that looked best preserved were sent out for thin section preparation. Unfortunately even the most promising of the outcrop samples have clearly undergone extensive recrystallization,. The alteration is so extensive that is very unlikely that chemical analyses could yield useful data. We have also obtained samples from the Stirt Basin in Lybia for analyses, these are somewhat better preserved, but no analytical work has been done on these samples yet.
Modeling work: Paquay has also worked with simple equilibrium models of inorganic carbon speciation , carbonate deposition, dissolution and burial with the aim of better constraining variations in the total dissolved inorganic carbon in seawater across the Eocene-Oligocene transition. As detailed in our proposal there are pronounced shifts in the CCD across this important climate transition. Some have suggested that this fluctuations may be related to pCO2 variations. These modeling efforts are designed to help test these ideas. These work is being done using Matlab in collaboration with with Richard Zeebe (also at University of Hawaii, Manoa).
Additional work beyond the scope of the original proposal: Having encountered problems with sample preservation in Eocene-Oligocene reef material, Paquay has embarked upon a separate geochemical study of trace metals in organic-rich sediments deposited in the Arctic Ocean during the mid-Eocene. The specific event targeted is the Azolla event. This event is represented by extensive deposition of fossil material from a variety of fresh water fern (Azolla). Independent geochemical data indicate greatly increased fresh water flux to the Arctic Ocean during this time. The goal of Paquay’s work is to determine if there is evidence that this Artic event left distinctive trace element signatures in other parts of the global ocean with the ultimate aim of determining if these Artic climatic fluctuations significantly perturbed the global carbon cycle. This work has been partially supported by a Schlanger Ocean Drilling Fellowship waward to Paquay.
Undergraduate Research: Since 9/09, a small amount of money for supplies has been used to supported some experimental work by an undergraduate student, Chuen Wing Lam, who is conducting experiments on mineral carbonation of olivine using differential scanning calorimetry. My interest in these experiments is in large part motivated by a hypothesis that extensive alteration of ultramafic rocks and associated carbon dioxide draw-down in the late Eocene played a causative role in the Greenhouse-Icehouse transition. While this is quite speculative, the result Wing is producing are of general interest to all those interested in mineral carbonation as a strategy for carbon sequestration. Although this is only tangentially related to our original proposal, this is new research in my lab and wholly in line with ACS objectives of support new lines of investigation and student research.
