Snapshots of climate variability: Improving methods for tracing seasonal and sub-annual variability in deep time using skeletal hardparts


Società Geologica Italiana

Giovedì 14 Novembre ore 15:00
Aula Geo 6 – Edificio 10
Università degli Studi Federico II
Dipartimento di Scienze della Terra dell'Ambiente e delle Risorse
Scuola Politecnica e dlle Scienze di Base
Complesso Universitario di Monte S. Angelo

Relatore: Niels de Winter (Dept. of Earth Sciences, Utrecht University, NL).

Reconstructions of climate in the past teach us about climate variability during various periods in Earth's history. While many paleoclimate studies have focused on climate reconstructions over long timescales (thousands to millions of years), the effect of climate change on short-term (years to decades) variability must be better understood to improve our models for future climate change. Incrementally growing skeletal hardparts such as bivalve shells are ideal archives for this short-term variability. In this presentation, Niels de Winter will take a critical look at the potential of these skeletal archives for preserving their original chemical composition in the fossil record, and how chemical proxies in these archives can be used as a proxy for climate.
 In order to test chemical proxies for high-resolution paleoclimate, multi-proxy studies were carried out on modern and fossil specimens. The combination of several proxies and techniques sheds light on the mechanisms that govern shell growth and chemistry, and allow the abundant fossils of extinct groups such as rudist bivalves to be used for high-resolution palaeoclimate research. This multi-proxy approach combines several new techniques and measurement strategies for obtaining high-resolution climate data: Micro X-Ray Fluorescence was applied for screening carbonate samples for diagenetic alteration and for quantitative trace element profiling. New applications of laser ablation ICP-MS allows high-resolution trace element profiling and mapping. Finally, first results will be presented on a new way to apply the clumped isotope technique for absolute seasonal temperature reconstructions from bivalve shells.
Niels de Winter obtained his MSc degree in Earth, Life and Climate in 2013 (Utrecht University) and his PhD in geochemistry in 2019 at the AMGC research group in Brussels (VUB). This year, he was awarded a Marie Curie Individual Fellowship from the European Commission and a Junior Postdoc Fellowship from the Flemish Research Council to carry out a 5-year project studying the incorporation of trace elements in bivalve shells and developing proxies for reconstructing temperature seasonality in various geological time periods. During his 5 years in Brussels, Niels supervised the analyses of trace elements using the AMGC's M4 microXRF scanner.