Abstract

Analyses of geomorphic, soil, and topographic data from the northern Yucatán Peninsula, México, confirm that the buried Chicxulub impact crater has a distinct surface expression and that carbonate sedimentation throughout the Cenozoic has been influenced by the crater. Late Tertiary sedimentation was mostly restricted to the region within the buried crater, and a semicircular moat existed until at least Pliocene time. The topographic expression of the crater is a series of features concentric with the crater. The most prominent is an ∼ 83-km-radius trough or moat containing sinkholes (the Cenote ring). Early Tertiary surfaces rise abruptly outside the moat and form a stepped topography with an outer trough and ridge crest at radii of ∼103 and ∼ 129 km, respectively. Two discontinuous troughs lie within the moat at radii of ∼ 41 and ∼ 62 km. The low ridge between the inner troughs corresponds to the buried peak ring. The moat corresponds to the outer edge of the crater floor demarcated by a major ring fault. The outer trough and the ∼ 62-km-radius inner trough also mark buried ring faults. The ridge crest corresponds to the topographic rim of the crater as modified by postimpact processes. These interpretations support previous findings that the principal impact basin has a diameter of ∼ 180 km, but concentric, low-relief slumping extends well beyond this diameter and the eroded crater rim may extend to a diameter of ∼ 260 km.

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