劳斯陨石坑：分层水冰丘的演变

Observations of a new stabilizing effect for polar water ice on Mars

Using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), we map the temporal variability of water ice absorption bands over the near-polar ice mound in Louth crater, Mars. The absorption band depth of water ice at 1.5 microns can be used as a proxy for ice grain size and so sudden reductions can time any switches from ablation to condensation. A short period of deposition on the outer edge of the ice mound during late spring coincides with the disappearance of seasonal water frost from the surrounding regolith suggesting that this deposition is locally sourced. The outer unit at…

Crater mound formation by wind erosion on Mars

Most of Mars' ancient sedimentary rocks by volume are in wind-eroded sedimentary mounds, but the connections between mound form and wind erosion are unclear. We perform mesoscale simulations of different crater and mound morphologies to understand the formation of sedimentary mounds. As crater depth increases, slope winds produce increased erosion near the base of the crater wall, forming mounds. Peak erosion rates occur when the crater depth is ~2 km. Mound evolution depends on the size of the host crater. In smaller craters mounds preferentially erode at the top, becoming more squat, while i…

Fluids mobilization in Arabia Terra, Mars: depth of pressurized reservoir from mounds self-similar clustering

Arabia Terra is a region of Mars where signs of past-water occurrence are recorded in several landforms. Broad and local scale geomorphological, compositional and hydrological analyses point towards pervasive fluid circulation through time. In this work we focus on mound fields located in the interior of three casters larger than 40 km (Firsoff, Kotido and unnamed crater 20 km to the east) and showing strong morphological and textural resemblance to terrestrial mud volcanoes and spring-related features. We infer that these landforms likely testify the presence of a pressurized fluid reservoir …

火星盖尔陨石坑土墩的生长和形成：斜坡风增强的侵蚀和运输

Growth and form of the mound in Gale Crater, Mars: Slope-wind enhanced erosion and transport

古代沉积物提供了火星气候和可居住性的档案。盖尔陨石坑是火星科学实验室（MSL）的着陆点，拥有一个5公里高的沉积丘。关于土墩形成的假说包括火山岩、湖泊、河流三角洲和风成过程，但盖尔土墩的起源和原始范围尚不清楚。在这里，我们展示了对土丘内沉积地层的新测量结果，表明从土丘中心径向向外倾斜约3度，与前三个假设不一致。此外，虽然土墩被广泛认为是一次陨石坑填充单位的侵蚀残留物，我们发现，大风土墩的目前形式是接近其最大程度。相反，我们建议，土墩的结构，地层，和目前的形状可以解释为在附近的火山口中心的风地形反馈介导的增长。我们的模型显示了沉积物最初是如何在远离火山口壁下降风的火山口中心附近堆积的，直到所产生的土丘的起伏越来越大，土丘侧面的斜坡风足够强，足以侵蚀土丘。我们的研究结果表明，土墩形成的大气沉降为主的沉积作用有限的湖泊和河流活动，并可能有限的有机碳保存。风和地形之间的形态动力学反馈广泛适用于火星表面的一系列沉积丘和冰丘，可能还有其他行星。

火星上沉积岩的季节性融化和形成，以及对盖尔陨石坑丘的预测

Seasonal melting and the formation of sedimentary rocks on Mars, with predictions for the Gale Crater mound

提出了火星上沉积岩形成和分布的模式。速率限制步骤是由雪或冰的季节性融化提供液态水。该模型是在O（10^2）mbar的纯CO2大气、尘雪和太阳光度降低23%的情况下运行的。在这些条件下，雪只在赤道附近融化，并且只有当赤道度>40度，离心率>0.12，近日点出现在春分点附近时才会融化。火星过去自旋轨道参数的概率分布的0.01-20%满足熔化的这些要求。总的熔融产物足以解释沉积岩的水蚀变。季节性融雪的模式是集成在所有的自旋轨道参数和观察到的分布相比，沉积岩。全球范围内的融雪分布在水手谷、子午线平原和盖尔火山口有最大值。这些对应于沉积岩分布的最大值。更高的压力和特别是更高的温度导致在更宽的自旋轨道参数范围内熔化。火星上的沉积岩模式与火星的古气候最为一致，火星的古气候很少产生足够的融水来沉淀含水胶结物和硬化沉积物。结果表明，融雪的不稳定性和长期的全球干燥间隔，对火星上过去的生命不利。这个模型为盖尔陨石坑的火星科学实验室漫游者做出了可测试的预测。盖尔陨石坑预计是火星上融雪的半球最大值。