Nicholson Uisdean, Bray Veronica J, Gulick Sean P S, Aduomahor Benedict
School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh, UK.
Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
Sci Adv. 2022 Aug 19;8(33):eabn3096. doi: 10.1126/sciadv.abn3096. Epub 2022 Aug 17.
Evidence of marine target impacts, binary impact craters, or impact clusters are rare on Earth. Seismic reflection data from the Guinea Plateau, West Africa, reveal a ≥8.5-km-wide structure buried below 300 to 400 m of Paleogene sediment with characteristics consistent with a complex impact crater. These include an elevated rim above a terraced crater floor, a pronounced central uplift, and extensive subsurface deformation. Numerical simulations of crater formation indicate a marine target (800-m water depth) impact of a ≥400-m asteroid, resulting in a train of large tsunami waves and the potential release of substantial quantities of greenhouse gases from shallow buried black shale deposits. Our stratigraphic framework suggests that the crater formed at or near the Cretaceous-Paleogene boundary (~66 million years ago), approximately the same age as the Chicxulub impact crater. We hypothesize that this formed as part of a closely timed impact cluster or by breakup of a common parent asteroid.
在地球上，海洋目标撞击、双撞击坑或撞击群的证据很罕见。来自西非几内亚高原的地震反射数据显示，在古近纪沉积物下方约300至400米处掩埋着一个宽度≥8.5公里的结构，其特征与复杂撞击坑一致。这些特征包括梯田状坑底上方的隆起边缘、明显的中央隆起以及广泛的地下变形。撞击坑形成的数值模拟表明，一颗直径≥400米的小行星撞击了海洋目标（水深约800米），引发了一系列巨大的海啸波，并可能从浅埋的黑色页岩沉积物中释放大量温室气体。我们的地层框架表明，该撞击坑形成于白垩纪-古近纪边界（约6600万年前）或其附近，与希克苏鲁伯撞击坑的年龄大致相同。我们推测，这是由紧密相连的撞击群或共同母体小行星的解体形成的。
