Int'l Dinner & Meeting - Drilling the Chicxulub impact structure: Resurfacing planets and links to life

The most recent of Earth’s five largest mass extinction events occurred 66 Ma, coeval with the impact of a ~12 km asteroid, striking at ~60 degrees into what is today the Yucatán Peninsula, México, producing the ~200 km-wide Chicxulub crater. This impact, by some estimations, drove the extinction of 75% of life on Earth at the genus level. The mass extinction event marks the boundary between the Cretaceous and Paleogene.  Proposed kill mechanisms include thermal effects caused by the reentry of fast ejecta into Earth’s atmosphere, dust and sulfate aerosols reducing Earth’s solar insolation, ocean acidification, and metal toxicity due to the chemical make-up of the impactor. The magnitude and duration of these processes is still debated, and further evaluation of the proposed kill mechanisms requires an understanding of the mechanics of the Chicxulub impact as well as the resulting global environmental perturbations.

In April and May 2016, the International Ocean Discovery Program, with co-funding from the International Continental Scientific Drilling Program, successfully cored into the Chicxulub impact crater with nearly 100% recovery. These cores include the first-ever samples of the transition from an intact peak ring through post-impact sediments.  A peak ring is a discontinuous ring of mountains observed within the central basin of all large impact craters on rocky planets. Newly drilled cores include the uplifted target rocks, melt-rich impactites, hydrothermal deposits, a possible settling layer, and the resumption of carbonate sedimentation.  The discovery that Chicxulub’s peak ring consists of largely granitic crust uplifted by ~10 km calibrates impact models and allows for observation of impact processes. At the top of the peak ring, the K-Pg boundary deposit includes a impactite sequence ~130 m thick deposited by processes that range from minutes to likely years post-impact.  This sequence is then overprinted by hydrothermal processes that lasted at least 100s Kyr post-impact and may have fed a subsurface ecosystem within the crater.  The full recovery of life within the crater spans from immediately after impact through millions of years allowing for a first-order assessment of the environmental consequences of the impact (“kill mechanisms”).

Location: Brookhaven Country Club
3333 Golfing Green Drive
Farmers Branch , TX 75234

Date: Nov. 15, 2017, 5:30 p.m. - Nov. 15, 2017, 8:30 p.m.