Large impact structures are characterized by peak ring and central uplifts with lateral/vertical mass transport during late formation stages. Here we investigate the Chicxulub crater, which has been surveyed by an array of marine, aerial and land-borne geophysical methods. Seismic reflection surveys in its central sector have shown lack of resolution, making it difficult to image the central uplift. We develop an integrated seismic and gravity model for the structural elements, imaging the central uplift and melt and breccia units. The 3D velocity model built from interpolation of seismic data is validated using perfectly matched layer seismic acoustic wave propagation modeling, optimized at grazing incidence using the shift in the frequency domain. Modeling shows that lack of illumination relates to seismic energy that remains trapped in an upper low-velocity zone corresponding to the carbonate sediments, upper melt/breccias and surrounding faulted blocks. After conversion of seismic velocities into a volume of density values, we apply parallel forward gravity modeling to constrain the size and shape of the central uplift, which has a ~ 40 km diameter concave upwards top lying at ~ 3.5–4.5 km depth. The preferred model provides a high-resolution image of crater units and structure. The gravity response of modeled units shows asymmetries in structure and the distribution of breccias, melt and target carbonates. Finally, we apply an adjoint reverse time migration approach for seismic imaging using the density and velocity models built for the acoustic wave propagation and gravity modeling, which allows improved modeling of the crater structure.

中文翻译：

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从大规模地震声波传播和重力建模对希克苏鲁伯中央陨石坑带进行成像

大型撞击结构的特点是峰环和中央隆起，在形成后期具有横向/垂直质量传输。在这里，我们调查了希克苏鲁伯陨石坑，该陨石坑已经通过一系列海洋、航空和陆上地球物理方法进行了调查。其中部地区的地震反射调查显示缺乏分辨率，因此难以对中部隆起进行成像。我们为结构元素开发了一个综合的地震和重力模型，对中央隆起、融化和角砾岩单元进行成像。使用完美匹配的层地震声波传播模型验证从地震数据插值构建的 3D 速度模型，使用频域偏移在掠入射时进行优化。建模表明，缺乏照明与地震能量有关，这些地震能量仍被困在与碳酸盐沉积物、上部熔体/角砾岩和周围断层块相对应的上部低速带中。在将地震速度转换为密度值体积后，我们应用平行前向重力建模来约束中央隆起的大小和形状，中央隆起的顶部有一个直径约 40 公里的向上凹面，深度约 3.5-4.5 公里。首选模型提供了火山口单元和结构的高分辨率图像。模拟单元的重力响应显示结构和角砾岩、熔体和目标碳酸盐的分布不对称。最后，我们使用为声波传播和重力建模建立的密度和速度模型，将伴随逆时偏移方法应用于地震成像，