Natural Resources Canada, Canada

Chicxulub is the best preserved large impact crater on Earth and, as such, assumes a crucial role in providing information on large-scale cratering processes and the global effects of such events. As the crater is buried approximately 1 km beneath the Yucatan surface, its structure has to be determined through geophysical exploration and drilling. Of most importance in these endeavors have been two seismic experiments acquired in 1996 and 2005, and a number of onshore exploration and scientific holes drilled by PeMex, UNAM and ICDP. However, to date, there are no drill holes offshore, nor any holes that penetrate the crater lithologies at depths of greater than 1650 m, hence there remain significant unknowns about the structure of this crater and the formation of large craters in general. To address this, a proposal for future joint IODP/ICDP drilling of this crater will be considered at a workshop in Potsdam in September 2006. Three holes have been previously proposed to IODP and ICDP: Chicx-01A, Chicx-02A and ICDP-2. Chicx-01A is an offshore hole through the target rocks aimed at characterizing their chemistry, porosity and volatile content, and quantifying the environmental effects of this impact. This hole will allow us to determine whether the thickness of the Cretaceous sediments increase offshore as suggested by the seismic reflection data. This is significant because the release of volatiles from these sediments are thought to have been particularly environmentally damaging. The aim of Chicx-02A is to penetrate the crater's peak ring and test models for peak ring formation. This is fundamental to understanding the cratering process as it tells us about the mechanics of large crater formation. If we can better understand crater formation on Earth, we can use impact craters as a diagnostic tool to probe the near surface of other planetary bodies. ICDP-2 will penetrate the impact melt rocks and central uplift, and will be used to characterize the petrology and geochemistry of the melts rocks, and determine the total volume of melt. In this presentation we will outline the results of deliberations at the workshop, and plans for future drilling at Chicxulub.