Impact-induced mantle dynamics on Mars
Impact-induced mantle dynamics on Mars
复制标题
撞击引起的火星地幔动力学
DOI：
10.1016/j.icarus.2011.11.038
复制
发表时间：
2011
期刊：
影响因子：
3.2
通讯作者：
J. Arkani‐Hamed
中科院分区：
文献类型：
--
作者：
J. Roberts;J. Arkani‐Hamed
在火星上发现了至少20个直径从1000公里到3380公里的撞击盆地，其中5个直径超过2500公里。碰巧撞击序列的结束时间和全球磁场的消失导致了对撞击加热使早期核心发电机瘫痪的调查。地核冷却的速度(因此发电机的活动)受上覆地幔的冷却速度的限制。因此，地幔先前存在的热状态控制着一系列撞击可能影响发电机活动的程度。在这里，我们研究了核和地幔的初始热结构，以及撞击相对于先前存在的对流结构的位置对地幔动力学和表面热通量的影响。我们发现，形成五个最大盆地的碰撞对地幔动力学的影响占主导地位。这种大小的一次撞击就可以改变地幔的整个流场。这样的撞击促进了撞击地点下方上升流的形成，导致了长时间的单羽对流。两次最大撞击之间的间隔比单次撞击的初始恢复时间短。因此，每一次撞击引起的对流模式的变化将导致全球热流的长期变化。这些长期变化是累积的，多重影响具有协同效应。
At least 20 impact basins with diameters ranging from 1000 to 3380km have been identified on Mars, with five exceeding 2500km. The coincidental timing of the end of the sequence of impacts and the disappearance of the global magnetic field has led to investigations of impact heating crippling an early core dynamo. The rate of core cooling (and thus dynamo activity) is limited by that of the overlying mantle. Thus, the pre-existing thermal state of the mantle controls the extent to which a sequence of impacts may affect dynamo activity. Here, we examine the effects of the initial thermal structure of the core and mantle, and the location of an impact with respect to the pre-existing convective structure on the mantle dynamics and surface heat flux. We find that the impacts that formed the five largest basins dominate the impact-driven effects on mantle dynamics. A single impact of this size can alter the entire flow field of the mantle. Such an impact promotes the formation of an upwelling beneath the impact site, resulting in long-lived single-plume convection. The interval between the largest impacts is shorter than the initial recovery time for a single impact. Hence, the change in convective pattern due to each impact sets up a long term change in the global heat flow. These long-term changes are cumulative, and multiple impacts have a synergistic effect.
影响因子：
3.2
作者：
Elbeshausen, Dirk;Wuennemann, Kai;Collins, Gareth S.
通讯作者：
Collins, Gareth S.