Layered ejecta craters and the early water/ice aquifer on Mars

Ejecta mobility of layered ejecta craters on Mars: Assessing the influence of snow and ice deposits

The unusual lobate ejecta deposits of martian impact craters have led to several proposed fluidization mechanisms to explain their morphology. Of the fluidized ejecta craters, double-layered ejecta (DLE) craters, believed to form in a decameters-thick surface ice layer, appear to have anomalously large and highly variable ejecta mobility (EM) ratios. We propose that low-aspect-ratio layered eje...

Testing landslide and atmospheric-effects models for the formation of double-layered ejecta craters on Mars

Double-layered ejecta (DLE) craters are distinctive among the variety of crater morphologies observed on Mars, but the mechanism by which they form remains under debate. We assess two ejecta emplacement mechanisms: (1) atmospheric effects from ejecta curtain-induced vortices or a base surge and (2) ballistic emplacement followed by a landslide of ejecta assisted by either surfaceor pore-ice. We...

Formation of double-layered ejecta craters on Mars: A glacial substrate model

[1] A class ofMartian impact craters with particularly unusual ejecta characteristics (double-layered ejecta (DLE) craters) are preferentially located in the midlatitudes in both hemispheres of Mars. Unlike today, decameters thick deposits of snow and ice occupied these same latitudes for significant periods during the Amazonian period. We assess the hypothesis that the unusual double-layer mor...

Morphology of Martian Double Layered Ejecta Craters and the Speed of Ejecta

Excess ejecta craters record episodic ice-rich layers at middle latitudes on Mars

[1] We infer Amazonian climate change events from the presence of fresh craters with excess volumes of ejecta. Using the Mars Orbiter Laser Altimeter data, the geometrical properties of 572 fresh impact craters with rim diameters between 2.5 and 102 km were compiled in lowland and highland plains. The data reveal a class of fresh craters with anomalously high ejecta volumes preferentially locat...