Deformation Features of the Cretaceous Units of the Icdp-chicxulub Drill

Introduction: The Yaxcopoil-1 (Yax-1) borehole, 60 km SSW of the center of the Chicxulub crater, penetrated through 600 m of sediments below the impactites (from about 894.9 m to the lowermost drilling depth of 1510.9 m). These rocks which are most likely of Cretaceous age are deformed to various degree and consist of distinct lithologies, predominantly carbonates and sulfates (dolomite, limestone and anhydrite). Based on the drill core ́s position between the inner peak ring and the crater rim and considering structural information of other large impact craters (e.g. Ries; Siljan), the sequence of Cretaceous rocks most likely represents displaced mega-block units of the crater floor which have been slumped from the rim of the transient crater towards their present position. To test this hypothesis, in particular the autochthonous or allochthonous character of the sediments, information on (a) the spatial extent of the rocks, (b) the inclination of bedding planes and (c) all types of deformation features are required. Structural analysis of the Cretaceous Sediments: (a) Spatial extent of sediments. Seismic reflection data, e.g. the Chicx-A seismic section [1], do not directly transsect the Yax-1 locality and, thus, provides no additional information on the spatial distribution of the sediments of the drillcore.