The Chicxulub impact crater in northwestern Yucatan, Mexico is the primary candidate for the proposed impact that caused mass extinctions at the end of the Cretaceous Period. The crater is buried by up to a kilometer of Tertiary sediment and the most prominent surface expression is a ring of sink holes, known locally as cenotes, mapped with Landsat imagery. This 165 ± 5 km diameter Cenote Ring demarcates a boundary between unfractured limestones inside the ring, and fractured limestones outside. The boundary forms a barrier to lateral ground water migration, resulting in increased flows, dissolution, and collapse thus forming the cenotes. The subsurface geology indicates that the fracturing that created the Cenote Ring is related to slumping in the rim of the buried crater, differential thicknesses in the rocks overlying the crater, or solution collapse within porous impact deposits. The Cenote Ring provides the most accurate position of the Chicxulub crater's center, and the associated faults, fractures, and stratigraphy indicate that the crater may be ∼240 km in diameter.

中文翻译：

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墨西哥尤卡坦州希克苏鲁伯撞击坑的地表地质

墨西哥尤卡坦西北部的希克苏鲁伯撞击坑是造成白垩纪末期大规模灭绝的拟议撞击的主要候选者。陨石坑被多达一公里的第三纪沉积物掩埋，最突出的表面表现是一圈沉洞，当地称为 cenotes，用 Landsat 图像绘制。这个直径为 165 ± 5 公里的 Cenote 环划定了环内未破裂石灰岩和环外破裂石灰岩之间的边界。边界形成地下水横向迁移的屏障，导致流量增加、溶解和坍塌，从而形成天然井。地下地质表明，形成 Cenote 环的裂缝与埋藏陨石坑边缘的坍塌、陨石坑上方岩石的不同厚度、或多孔冲击沉积物中的溶液坍塌。Cenote Ring 提供了希克苏鲁伯陨石坑中心最准确的位置，相关的断层、裂缝和地层表明该陨石坑的直径可能约为 240 公里。