The Biology and Paleo Environment Seminar Series presents:
Dr. Reinhard Kozdon, Lamont Associate Research Professor, Biology and Paleo Environment.
Abstract: Since about seven decades, the oxygen isotope composition of the calcite shells of benthic and planktic foraminifera, sand-grain-sized microfossils that are ubiquitous in the deep-sea sedimentary record, has been widely employed for the compilation of paleoclimate data. Thus, fossil foraminiferal shells are arguably the most important and best-studied paleoclimate archive, and many of the longest and most-continuous paleoclimate records have been compiled from foraminifera-rich seafloor sediments. The shells of foraminifera are chemically and isotopically zoned on micrometer scales as a result of the complex mechanisms of biocalcification combined with environmental changes such as vertical migration through the water column during the life cycle of planktic species. After the shell is deposited on the sea floor, this compositional heterogeneity may be superimposed by diagenetic alteration or the selective dissolution of portions of the shell.
Conventionally, multiple pooled shells are being analyzed, and their isotopic and chemical heterogeneity is averaged to a single value for the compilation of paleoclimate records. Therefore, valuable information recorded in the compositional heterogeneity is lost. In situ (measurements “in the original place”) technologies allow for the analysis of micrometer-sized domains within foraminiferal shells and thus facilitate the identification and quantification of isotopic and chemical intrashell variability. In this seminar, I will present results from in situ analyses of foraminiferal shells that help to improve our understanding of foraminiferal shell calcification, to enhance the fidelity of paleoclimate records derived from relatively modern as well as from Paleogene foraminifera, to identify long-standing challenges in deducing reliable paleotemperatures from the high-latitude oceans, and to resolve discrepancies between proxy-data and model simulations from past climate analogues.
Bio: Dr. Reinhard Kozdon has a background in geology and paleontology. His dissertation work focused on assessing the potential of calcium isotopes in foraminiferal shells as a new temperature proxy. During his postdoctoral research at UW-Madison, he was the leading scientist developing the analytical methodologies required to measure the oxygen isotope composition in 10 µm spot sizes within foraminiferal shells. After exploring the suitability of cold-water corals as a deep-sea proxy recorder at Rutgers University, he now works at Lamont with a main focus on improving the fidelity of paleoclimate records from critical past climate analogs as well as on the development of new methods to analyze isotopically zoned minerals formed in rocks during carbon capture and storage.
