Seismic images of Chicxulub impact melt sheet and comparison with the Sudbury structure
Seismic images of Chicxulub impact melt sheet and comparison with the Sudbury structure
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希克苏鲁伯冲击熔体片的地震图像及与萨德伯里结构的比较
DOI：
10.1130/2010.2465(07
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发表时间：
2010
影响因子：
2.2
通讯作者：
M. Warner
中科院分区：
文献类型：
--
作者：
P. Barton;R. Grieve;J. Morgan;A. Surendra;P. Vermeesch;G. Christeson;S. Gulick;M. Warner
希克苏鲁伯陨石坑是地球上唯一已知的具有完整保存的峰环的撞击结构，它形成了研究大型撞击结构和了解地球和其他行星上的大规模陨石坑的重要天然实验室。 1996 年和 2005 年收集的地震数据揭示了希克苏鲁伯中央盆地最上面火山口的详细图像。地震反射剖面显示，在明显的火山口底部下方约 1 公里处有一个反射层，顶部是向上凹的反射器，被解释为碟形的基台。该反射层的上部与通过分析 6 公里地震拖缆数据的折射而确定的薄高速层重合。高速层几乎是水平的，似乎包含在峰环结构内。我们认为，该反射层是预计在撞击过程中形成的连贯熔体片，它可能与萨德伯里撞击结构中被称为萨德伯里火成岩复合体的单元相当。萨德伯里火成岩杂岩被解释为差异化的冲击熔体片，似乎具有相似的规模和几何形状，以及由顶部的高速层和下方的速度反转组成的最上面的岩性序列。这一比较表明希克苏鲁伯冲击结构还包含连贯的差异化熔体片。
Chicxulub is the only known impact structure on Earth with a fully preserved peak ring, and it forms an important natural laboratory for the study of large impact structures and understanding of large-scale cratering on Earth and other planets. Seismic data collected in 1996 and 2005 reveal detailed images of the uppermost crater in the central basin at Chicxulub. Seismic reflection profiles show a reflective layer ~1 km beneath the apparent crater floor, topped by upwardly concave reflectors interpreted as saucer-shaped sills. The upper part of this reflective layer is coincident with a thin high-velocity layer identified by analyzing refractions on the 6 km seismic streamer data. The high-velocity layer is almost horizontal and appears to be contained within the peak ring structure. We argue that this reflective layer is the predicted coherent melt sheet formed during impact, and it may be comparable with the unit known as the Sudbury Igneous Complex at the Sudbury impact structure. The Sudbury Igneous Complex, interpreted as a differentiated impact melt sheet, appears to have a similar scale and geometry, and an uppermost lithological sequence consisting of a high velocity layer at the top and a velocity inversion beneath. This comparison suggests that the Chicxulub impact structure also contains a coherent differentiated melt sheet.