Chicxulub crater formed ~ 66 Ma ago by an asteroid impact on the Yucatan platform in the southern Gulf of Mexico. The crater has a ~ 200 km rim diameter and has been covered by carbonate sediments up to ~ 1.1 km thick in the central zone. Previous studies have identified the structure and major crater units through geophysical models from seismic reflection and potential field data, classified as the central uplift, terrace zone, outer and inner ring fault zones and impactite deposits. Impact produced a deep excavation cavity, with fragmentation and ejection of large volumes of crustal target rocks. Understanding the pre-existing structures, impact-induced deformation and post-impact processes requires high-resolution images of the crater and target zone. For this study, we use complex trace attributes of instantaneous phase, frequency, envelope amplitude and similarity, in an E-W seismic reflection profile crossing the crater in the marine sector. Geophysical logs and borehole lithological columns from the on-land drilling projects are used to constrain the petrophysical analysis. Seismic attributes aid to characterize the radial fault zones and physical property contrasts, revealing asymmetries in the crater structure. The reflector packages in the post-impact sediments and target Cretaceous sequence are identified in the frequency and phase attributes. The bottom crater reflectors, with the basal sediments filling the crater floor topography, are enhanced with the envelope amplitude attribute. A set of high-amplitude reflectors is shown in the similarity attribute, in which the reflector geometry is delineated on the target carbonate sequence. The offsets in the high-amplitude reflectors between the eastern and western sectors are possibly associated to target pre-impact asymmetries, impact deformation and effects of central crater collapse.

中文翻译：

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Chicxulub撞击坑的地震属性分析

Chicxulub火山口形成于约66 Ma之前，是由小行星撞击墨西哥南部海湾的尤卡坦半岛平台形成的。火山口的轮缘直径约为200公里，中心地区的碳酸盐沉积物覆盖的厚度约为1.1公里。先前的研究已通过地球物理模型从地震反射和势场数据中识别出了结构和主要陨石坑单元，这些数据被分类为中央隆起，阶地带，内外断层带和内冲断层沉积。撞击产生了一个深的开挖腔，破碎并弹出了大量的地壳目标岩石。要了解现有的结构，撞击引起的变形和撞击后的过程，就需要火山口和目标区域的高分辨率图像。在这项研究中，我们使用瞬时相位，频率，跨海域火山口的EW地震反射剖面中的包络振幅和相似度。来自陆上钻探项目的地球物理测井和钻孔岩性柱被用来约束岩石物理分析。地震属性有助于表征径向断层带和物理性质的对比，揭示出火山口结构的不对称性。在频率和相位属性中确定了撞击后沉积物和目标白垩纪层序中的反射器组。底部火山口反射器的底部沉积物填充了火山口地面的地形，并通过包络幅度属性进行了增强。在相似性属性中显示了一组高振幅反射器，其中反射器的几何形状在目标碳酸盐序列上描绘。