MICROPALEONTOLOGY

Background: The study of microfossils, skeletons of organisms that you need a microscope to see well, has been used extensively in many branches of the Earth Science. Their use in reconstructing marine and terrestrial environments, especially for the Pleistocene, has grown enormously over the past several decades. The key to doing this lies in adequately modeling the ecologic behavior of the various microfossil groups. My research group has focused on the Foraminifera, marine ameobas that secrete a calcite shell, and their use in reconstructing properties of the global ocean during the Late Pleistocene. Our purpose has been the study of global climate change.

WHAT ARE WE DOING?

A decade ago our research focused on planktonic foraminifera, those that float in ocean surface waters. Since that time we have turned to the benthic foraminifera as tracers of Surface Ocean Biological Productivity. Oceanic productivity depends a biogeochemical cycles in the oceans and reflects a number of aspects of the global climate system. There have been relatively few methods developed for the quantitative reconstruction of oceanic productivity over time scales of 100's to thousands of years. We have developed a technique using benthic foraminiferal species abundances in deep sea sediments. The benthic organisms are tied to the surface ocean biological activity because the surface ocean is the ultimate source of food for those living on the seabed.

In addition to tracing organic carbon production, we have integrated the use of microfossil calcite preservation indices with chemical, isotopic and radiochemical analysis of deep sea sediments to reconstruct fluxes of both organic carbon and calcite into the deep sea.  This is important since the ratio of these fluxes appears to have an important effect on the overall exchange of carbon dioxide between the oceans and the atmosphere.

We also have developed a means of reconstructing deep ocean oxygen content using benthic foraminifera. That oxygen content reflects overall ocean circulation and the transport of organic carbon/carbon dioxide into the deep sea. There are currently no other techniques available to directly reconstruct this paleoenvironmental variable. The benthic foraminifera appear to reflect bottom water oxygen content as this influences the biogeochemical processes that they live with in the deep sea sediments.

Finally, we have researched the processes involved in converting the living population of benthic foraminifera into a fossil record. This conversion is not a straight forward process, so examination of living communities does not always allow us to interpret the fossil record directly. Our work has helped define both the generation of shell material that can enter the geological record, and its ultimate preservation to give us the fossil assemblages we see in the sediment profiles of deep sea cores. We have focused on the link between seabed biogeochemical processes and the formation and preservation of benthic shell material.

FOR MORE INFO. VIA PUBLICATIONS PRESS HERE (Biogeochemistry)

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