A Triple Threat: Stable Isotopes of Fluid Inclusions, Clumped Isotopes and Conventional Oxygen Isotopes from Modern and Ancient Caves in the Bahamas

Wednesday, 17 December 2014
Peter K Swart1, Monica M Arienzo1 and Sevag Mehterian2, (1)RSMAS, Miami, FL, United States, (2)University of Miami, Miami, FL, United States
The δ13C and δ18O of speleothems are widely used as environmental proxies in spite of the fact that it is acknowledged that they are significant non-equilibrium problems associated with their formation. Although some attempts have been made to test for kinetic effects by lateral sampling such kinetic effects still remain are emphasized by the large departure of the temperatures calculated using the Δ47proxy in speleothems.

Here we present data from conventional δ18O isotopes in modern and ancient samples from the same cave and compare these with δ18O w analyses from drip water and from fluid inclusions. Finally these data are compared with Δ47 measurements. These data show that it is possible to reconcile all the data using the approach of Wainer et al. (Quaternary Science Reviews, 30, 130-146, 2011) which compares the offset of the Δ47 from the correct value and the difference between the δ18O data and the Kim and O'Neil ( Geochimica et Cosmochimica Acta, v. 61, 3461-3475, 1997) relationship in the modern samples. Using this slope the kinetic fractionation can be accounted for and a temperature estimated. The relationship can then be applied to ancient stalagmites from the Bahamas to distinguish between temperature and δ18Ow influences during important climatic events such as the Heinrich stadials. These data can then be verified by using the alternate approach of distinguishing temperature and δ18Ow, using the δ18O of water extracted from fluid inclusions to correct the δ18O of the calcite. Such suggested minimal changes in the δ18Ow and larger changes in temperatures during Heinrich events in the sub-tropics.