Institut für Geo- und Umweltnaturwissenschaften, Albert-Ludwigs-Universität Freiburg, Baden-Württemberg, Germany.
Casper College, Casper, WY, USA.
Sci Rep. 2018 Sep 5;8(1):13246. doi: 10.1038/s41598-018-31655-4.
The Earth is constantly bombarded by meteoroids of various sizes. During hypervelocity collisions a large amount of energy is coupled to the Earth's atmosphere leading to disruption of decimeter to hundred meter-sized meteoroids. Smaller meteoroids may form meteorite strewn fields while larger initial bodies and high-strength iron meteoroids may form impact crater strewn fields. Impact crater strewn fields are ephemeral and none documented to date are older than about 63,500 years. Here we report on a newly discovered impact crater strewn field, about 280 Myr old, in tilted strata of the Rocky Mountains near Douglas, Wyoming. It is the oldest and among the largest of impact crater strewn fields discovered to date, extending for a minimum of 7.5 km along a SE-NW trajectory. The apparent width of the strewn field is 1.5 km, but the full extent of the crater strewn field is not yet constrained owing to restricted exposure. We probably see only a small section of the entire crater strewn field. The cascade of impacts occurred in an environment that preserved the craters from destruction. Shock lithification aided this process.
地球不断受到各种大小的流星体的轰炸。在超高速碰撞过程中，大量能量被传递到地球大气层中，导致分米到百米大小的流星体解体。较小的流星体可能形成陨石散落场，而较大的初始天体和高强度的铁陨石可能形成撞击坑散落场。撞击坑散落场是短暂存在的，目前没有记录到比 63500 年更早的。在这里，我们报告了一个新发现的撞击坑散落场，位于怀俄明州道格拉斯附近的落基山脉倾斜地层中，距今约 2.8 亿年。这是迄今为止发现的最古老和最大的撞击坑散落场之一，沿 SE-NW 轨迹延伸至少 7.5 公里。散落场的明显宽度为 1.5 公里，但由于暴露有限，散落场的完整范围尚未确定。我们可能只看到了整个散落场的一小部分。一连串的撞击发生在一个可以防止陨石坑被破坏的环境中。冲击石化有助于这一过程。
