North-Central Section - 50th Annual Meeting - 2016

Paper No. 18-9
Presentation Time: 1:30 PM-5:30 PM


PARKER, Wesley1, YANES, Yurena1, SURGE, Donna2 and MESA, Eduardo3, (1)Department of Geology, University of Cincinnati, Cincinnati, OH 45221, (2)Geological Sciences, University of North Carolina at Chapel Hill, 104 South Road, CB #3315, Chapel Hill, NC 27599, (3)Departamento de Prehistoria, Arqueología e Historia Antigua, Universidad de La Laguna, La Laguna, 38200, Spain,

The limpet genus, Patella, has been established as a credible repository of sub-monthly paleotemperature data at high and mid latitudes. However, these shells have not been extensively studied in low-latitude environments, where climatic variations are comparatively subdued and shell growth may be continuous throughout all seasons. The Canary Islands, located 95km from the Atlantic coast of Morocco at 27-29oN, provide an ideal location for studying these shells at subtropical latitudes considering that (1) Patella is plentiful in the modern rocky intertidal shore and (2) archeological shells are well-preserved and abundant in shell middens expanding back in time ~2,500 years. Moreover, oxygen isotope ratios (δ18O) of local seawater do vary seasonally allowing us to constrain this parameter for estimating sea surface temperature (SST) from shell carbonate.

We analyzed the δ18O values of live-collected Patella shells using two different sampling approaches. First, live-collected limpets were sampled using a manual Dremel drill along the calcitic shell margin, which provided bulk (averaged) δ18O values at the time of specimen collection. Second, several modern limpets were cross-sectioned from anterior to posterior parallel to the maximum growth axis and microsampled sequentially at high resolution using a Merchantek micromill.

Bulk shell margin δ18O values correlated negatively with observed SST (R2=0.95; p<0.001; n=98). These results suggest that the high-resolution oxygen isotope time series of Patella crenata records seasonal variations in SST. Ongoing oxygen isotope analyses from high-resolution micromilled samples will allow us to reconstruct SST at sub-monthly scale during the late Holocene using archaeological P. crenata from the Canary Islands.