Over 2000 ash layers, representing approximately 65 million years of Central American explosive volcanic history, were discovered in cores recovered from four drilling sites in the Western Caribbean during leg 165 of the Ocean Drilling Project (ODP). There is much that is still unknown about the volcanic centers and eruptive processes that produced and deposited these tephra layers. Physical properties of the tephra layers, such as thickness, stratification and ash particle size, can provide information about the source eruptions and the depositional processes that produced the layers. A subset of the tephra layers will be analyzed to infer the magnitude, intensity and frequency of the source eruptions. Additionally, sedimentological and compositional features of the layers will be examined to determine if the layers are primary fallout or gravity-flow deposits. The overall vertical distribution of the ash layers will be used in an attempt to correlate volcanic events between sites and to estimate the number of individual eruptions represented in the cores. Finally, an atmospheric ash dispersion model will be used to simulate the conditions necessary to produce the observed fallout patterns. The model will also be used to evaluate potential changes in the paleowind conditions in the Central American region during the last 65 million years. In summary, this study will utilize deep-sea tephra layers to determine characteristics of past Central American volcanism, to identify possible methods of tephra deposition, and to infer paleowind conditions of the Central American region throughout the Cenozoic.

CAVA Geochemistry
- 7/15/05

Subduction Zones
- 2/15/05

The Day After Tomorrow
- 2/2/05

Volcanoes and Climate
- 1/14/05

Lucy
- 9/16/04

Volcanic Ash
- 8/13/04

Venus Transit
- 6/2/04

Subglagial Volcanism
- 5/26/04