Marking the southwestern coast of Europe, the Iberian Peninsula (IP) is a hotspot for studying transitions of climatic signals from high-to-mid latitudes, because it is a sensitive region to abrupt climatic variations. There are numerous paleoclimate studies on marine cores from the Iberian Margin that reveal synchronous changes in SST inferred from isotopic ratios (O18/O16) of foraminifer shells and terrestrial plant species from pollen records deposited from land. However, lack of data from terrestrial proxies necessitates investigation of local responses to climate forcing, which may show different patterns.
In this study, we analyzed stalagmites from Rabbit Farm cave (39°18’31.25″N, 9°16’36.73″W) in the western coast of Portugal to extend a previous study conducted on stalagmites from the nearby Glory Hole and Almanda caves that dated back to 132000 years ago, and to get a more complete picture of climatic changes in this area.
We determined the ratios of oxygen (O18/O16) and carbon (C13/C12) isotopes in the stalagmite calcite (CaCO3), because they reflect local or regional climatic changes. With the dates obtained by U-Th dating to get the chronologies of the stalagmites, we developed age models to construct isotopic profiles of the stalagmites through time. We then compared the profiles with records from other regions to see if there were teleconnections among the records.
We found that the stalagmites from Rabbit Farm cave respond to regional and local variabilities. While they stopped growing during major Heinrich events, there is no sign of deglaciation around 178,000. Years ago that are present in Greenland records, alluding to dominance of local factors.
Setsen Altan-Ochir, ’15
Sponsor: Rhawn Denniston