Paleoceanographers have learned how to extract climate change information from all aspects of the sedimentary record. We can split these approaches into three categories: coarse fraction, fine fraction and organic fraction (organic biomarkers). I generally work with the coarse and fine fractions of sediments recovered by oceanic or aquatic drilling.
Coarse fraction studies might include analysis of ice-rafted detritus, which are large clasts of sediment carried by icebergs or sea ice. In my laboratory, we focus on the carbonate component of the coarse fraction. I use micropaleontological and stable isotope analysis of foraminifera to answer questions about climate change.
Because many parts of the ocean lack carbonate sediment due to dissolution, I developed methods to extract paleoclimate data from fine fraction as well. This allows me to extract useful information from parts of the ocean where carbonate-based proxies have limited utility.
My fine-fraction work focuses on the physical properties of sediments using:
- Visible spectroscopy
- Magnetic susceptibility
- Laser particle size analysis
- Elemental analysis by x-ray fluorescence
These techniques allow me to reconstruct sediment transport, sediment sources and climate change through time.
These methods are rapid. They require little sample preparation, but yield data sets packed with climate information. I then use multivariate statistical methods to unmix this information and learn about the processes recorded in the sediment record. My work on color reflectance led me to develop enhanced methods based on the derivatives of spectral signatures. This visible derivative spectroscopy is the tool that I use most frequently, and I am now a world leader in the use of this technique for paleoclimatic reconstructions.