UTIG RESEARCH PROJECTS ARCHIVE

UTIG scientists involved with the 1996 Chicxulub OBS program: Yosio Nakamura, Ben Yates, Gail Christeson, Richard Buffler, John Brittan (from Imperial College).

Chicxulub Research Cruise Movie

Principal Investigators: Richard T. Buffler, Gail Christeson, and Yosio Nakamura

Funded by: National Science Foundation

Imperial College Chicxulub homepage
Philippe Claeys' latest Chicxulub page

The Chicxulub structure occurs along the northern coast of the Yucatan peninsula in the Gulf of Mexico. It is buried beneath up to a kilometer of Tertiary carbonates. Its upper boundary has been drilled, and it has been mapped on the basis of potential field and Landsat data. It is now widely believed that the Chicxulub structure represents a large meteorite impact that was responsible for the mass extinctions at the Cretaceous-Tertiary (KT) boundary.

The purpose of this joint project is to image in detail the internal crustal structure and morphology of the Chicxulub impact crater and to quantify its dimensions. The project involves the collection, processing and interpretation of a series of deep penetration seismic reflection profiles, wide-angle seismic measurements, and refraction measurements from the offshore portion of the crater. It represents a joint collaborative effort between the British Institutions Reflection Profiling Syndicate (BIRPS) (UK), the Canadian Geological Survey, Imperial College (UK), the Lunar and Planetary Institute, the Universidad Nacional Autónoma de México (UNAM), and The University of Texas Institute for Geophysics (UTIG).

UTIG deployed an array of OBS instruments along two key lines. The OBS wide-angle and refraction data were collected at the same time as the reflection data and are being integrated with the land-based wide-angle data to model the velocity structure of the Chicxulub crater.

The OBS instruments were deployed from the UT-MSI RV Longhorn based out of Port Aransas. Data were collected along lines totaling about 500 km. UTIG students and technical support participated in the data acquisition along with UNAM and PEMEX observers. Canadian Geological Survey personnel also were aboard to collect gravity and magnetics data, and John Brittan from Imperial College helped coordinate activities with the seismic reflection program.

Primary Objectives

• Constrain radial extent of impact structure.
• Determine position of the top, base and edges of the impact melt sheet and, hence, its total volume.
• Constrain amount and style of deep basement uplift and its later extent.
• Measure thickness of the crust outside the region of the basement uplift and within the crater itself.
• Determine the style of faulting and deformation on the flanks of the structure.
• Measure degree of radial asymmetry of the major structural and morphological elements within the crater.
• Infer position and depth of transient crater, the depth of crustal excavation, and the depth to which the lithosphere was fractured.

Broader Objectives

• Extend and improve the scaling laws for large impact events.
• Improve our understanding and models of ring formation for large impact basins.
• Improve our models and understanding of the process and extent of the central uplift.
• Quantify the amounts of potential environmental pollutants (dust, oxides of carbon, sulfur, and nitrogen) released by the impact.