Seasonal Resolution Paleoclimate Records from Modern and Archaeological Mollusk Shells (Project ID=paleo-1)
Faculty Sponsor Kathleen Johnson
      Seasonal-resolution paleoclimate records would allow the investigation of the role of seasonality in controlling mean climate and of the natural variability in climate patterns such as El Nino. Seasonal resolution climate archives are scarce, however, especially outside the range of tropical surface corals. Recently marine mollusk shells have been shown to preserve seasonal-resolution climate variations within their growth bands. The isotopic and chemical composition of a marine mollusk shell is related to the seawater temperature and salinity at the time it forms. Therefore, by analysing the stable isotope and trace element composition of successive samples along the cross-section of a shell, seawater temperatures and salinity experienced by the mollusk over its lifetime can be reconstructed. This can be demonstrated in modern mollusc shells from the California coastline by comparing the results with instrumental records. Fossil shells can then be analysed to provide some of the first seasonal-resolution paleoclimate records from California. Due to sea-level changes, however, fossil intertidal shells can be difficult to find in the field. Fortunately, though, over the last 10,000 years or more, humans have collected mollusks for food and there are many shells available from archaeological sites along the California coastline and on the Channel Islands.
      This project will involve microsampling of modern and archaeological marine mollusk shells and stable isotope and trace element analysis by mass spectrometry techniques to produce seasonal-resolution sea surface temperature and/or salinity records for California. The shells will also need to be radiocarbon dated to provide an accurate age. Students would gain experience in computer controlled micromilling, microbalances, stable isotope mass spectrometry, analytical chemistry, ICP-MS, and radiocarbon sample preparation. (Project Time Allocations: Sample Prep./Microscope Lab = 50%, Chemistry/Mass Spectrometry Lab = 50%).

Back to UCI REU Projects Back to UCI REU Homepage Earth System Science Department