The Chicxulub crater drilling program – continuous coring, well logging and core analyses reviewed

Continuous core recovery, core scanning and logging are used for borehole characterization and petrophysical analyses in the Chicxulub drilling projects. The crater formed by an asteroid impact on the Yucatan platform ~66Ma ago, marking the Cretaceous/Paleogene (K/Pg) boundary. The K/Pg boundary clay layer, characterized by the Ir and platinum group element anomaly, has been studied worldwide. The crater has a ~200km rim diameter and is covered by up to ~1km of carbonate sediments, with studies based on geophysical surveys, drilling and ejecta deposits. The Yaxcopoil-1 borehole, drilled in the southern crater terrace zone sampled the post-impact carbonates, impact breccias and target Cretaceous carbonates. The M0077A borehole drilled in the marine sector sampled the peak ring succession, with the post-impact carbonates, impact breccias, melt and basement. The Yaxcopoil-1 and M0077A boreholes were continuously cored from about 400m to 1511 and 1335m, respectively and sampled distinct crater structures. Studies provide constraints on the crater formation, crustal deformation, lateral/vertical displacement, ejecta emplacement and crater collapse. Impact breccias are heterogeneous materials, with clasts of melt, carbonates and basement in carbonate-rich and melt-rich matrix. The lower breccias were emplaced by high-temperature basal surges, followed by collapse of the impact plume and lateral curtains. The upper breccias are reworked deposits of the post-collapse stage. The crater formed a depositional basin, filled with sediments that preserve records of sea level and sediment transport across the platform. Core analyses and scans provide constraints on the structure, stratigraphy, textures, mineralogy, deformation and hydrothermal alteration. Studies show the usefulness of continuous coring and core analyses to constrain the crater formation, impact deformation, ejecta and impact dynamics.