Seismic Signature of the Haughton Structure

Abstract

Abstract— The western flank of the Haughton impact structure was imaged with a reflection profile generating 9.8 km of subsurface information. Ten reflecting horizons were recognized and have been correlated via a sonic log with the Paleozoic limestone/dolomite rock sequences. The seismic section is dominated by a dense and complex compound fault system with variable attitudes. These steeply dipping faults penetrated the sedimentary rocks but showed no recognizable extension into the crystalline basement. According to the seismically recognized fracture zones of the western margin, the structure is significantly larger than previously estimated. Reconstruction of the crater on the basis of the seismic information and existing scaling relationships reveals a structure with an apparent diameter of 23.9 km, and an excavated cavity of 10.3 km width and 1.97 km depth. The estimated diameters of the transient crater and the central uplift are 12 km and 11 km respectively. The morphologically distinct ring zones do not have seismically recognizable subsurface signatures. The underlying crystalline basement rocks did not exhibit seismically mappable impact‐related zones of disturbance. In the central interior region, coherent reflection signals are virtually absent. Valuable information for this area was provided by a 10.26 km long refraction profile that indicated nearly uniform velocities (∼5000 m/s) to a considerable depth. Major lateral variations in the velocity field across the structure were not detected.