LARLE crater information

A low-aspect-ratio layered ejecta crater (LARLE crater) is a class of impact crater found on the planet Mars. This class of impact craters was discovered by Northern Arizona University scientist Professor Nadine Barlow and Dr. Joseph Boyce from the University of Hawaii in October 2013.^[2] Barlow described this class of craters as having a "thin-layered outer deposit" surpassing "the typical range of ejecta". "The combination helps vaporize the materials and create a base flow surge. The low aspect ratio refers to how thin the deposits are relative to the area they cover", Barlow said.^[3] The scientists used data from continuing reconnaissance of Mars using the old Mars Odyssey orbiter and the Mars Reconnaissance Orbiter. They discovered 139 LARLE craters ranging in diameter from 1.0 to 12.2 km, with 97% of the LARLE craters found poleward of 35N and 40S. The remaining 3% mainly traced in the equatorial Medusae Fossae Formation.

LARLE craters are characterized by a crater and normal layered ejecta pattern surrounded by an extensive but thin outer deposit which ends in a flame-like shape.^[1] The ejecta layers of LARLE craters have higher aspect ratios compared with base surge deposits from explosion craters. This difference is probably caused by large amounts of small particles of dust and ice in the areas where LARLE craters form. This ice and dust came from mantles of snow and dust that were deposited during the many climate changes in Martian history. After the impact, deposits are quickly stabilized (order of a few days to a few years) from eolian erosion by formation of a crust formed from diffusion of water vapor out of the deposits.^[4] LARLE craters may be useful as a marker of ice under the surface.