9316207 Boyle PIs have found iridium (Ir) anomalies in ice cores associated with the 1908 Tunguska event and the 1783 Laki eruption. In collabooration with Robert Rocchia (Paris), they will extend these analyses to other ice cores with the following goals: 1) test and verify findings, 2) make systematic studies on ice core samples to clarify partitioning of Ir, and 3) investigate temporal variability of background Ir deposition. Results have implications for debate over impact vs. volcanic sources for iridium in the stratigraphic record, and also for linking volcanism and impacts to climatic changes.
