论文标题：A steeply-inclined trajectory for the Chicxulub impact

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作者：G. S. Collins, N. Patel et.al

发表时间：2020/05/26

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本周发表的一项研究A steeply-inclined trajectory for the Chicxulub impact指出，墨西哥的希克苏鲁伯陨石坑（Chicxulub crater）是一次较大倾角（与水平面夹角45度到60度之间）的小行星撞击造成的。

形成希克苏鲁伯陨石坑（约在6600万年前）的小行星撞击曾对地球环境带来毁灭性影响，被普遍认为与同时期发生的物种大灭绝事件有关。不过，撞击轨迹一直存在争议。

希克苏鲁伯陨石坑的地球物理学特征不对称。

credit: Collins et al.

英国帝国理工学院的Gareth Collins和同事利用一个模型模拟了希克苏鲁伯陨石坑的形成，以确定小行星飞来的方向和撞击角度。他们利用3D数值模拟分析了四种不同的撞击角度：90度、60度、45度、30度。基于这些数据和地球物理观测结果，作者认为，该陨石坑是由来自东北方向的一次倾角较大（与水平面夹角45度–60度）的撞击造成的。作者指出，这一撞击角度使得陨石坑的抛射物质几乎呈对称分布，撞击物每单位质量释放的会导致气候变化的气体也多于另外几种测试情景。

摘要：The environmental severity of large impacts on Earth is influenced by their impact trajectory. Impact direction and angle to the target plane affect the volume and depth of origin of vaporized target, as well as the trajectories of ejected material. The asteroid impact that formed the 66 Ma Chicxulub crater had a profound and catastrophic effect on Earth’s environment, but the impact trajectory is debated. Here we show that impact angle and direction can be diagnosed by asymmetries in the subsurface structure of the Chicxulub crater. Comparison of 3D numerical simulations of Chicxulub-scale impacts with geophysical observations suggests that the Chicxulub crater was formed by a steeply-inclined (45–60° to horizontal) impact from the northeast; several lines of evidence rule out a low angle (<30°) impact. A steeply-inclined impact produces a nearly symmetric distribution of ejected rock and releases more climate-changing gases per impactor mass than either a very shallow or near-vertical impact.

（来源：明升手机版(明升中国)）