Martian Buried Basins and Implications for Characteristics of the Burial Layer and Underlying Surface

Introduction: Deciphering the cratering record on Mars has been challenging because it may reflect the changes in both the population of impactors and in the resurfacing processes on Mars. However, it is possible to determine the breadth of impactors captured in the cratering record. Extensive areas of resurfacing are of particular interest because they likely contain material from various ages in Martian history. By deducing the impact populations in both surface and underlying layers of terrain, it is possible to determine the age of the layers and constrain theories on the development of the Martian surface. However, to do so requires a method of " seeing " impact features which are no longer visible. Topographic data of Mars, taken by the Mars Or-biter Laser Altimeter (MOLA), has revealed impact features buried by resurfacing processes. These features are often indistinguishable on Viking images of the Martian surface. In this study, gridded MOLA data was analyzed in order to locate buried impact features, also called buried basins, in Syria, Solis, and Sinai Planum just south of Valles Marineris. The population statistics of buried features can be compared to those of visible features in order to determine the age of the underlying material and characteristics of the surface cover. Specifically, if the buried population in the Hesperian terrain is similar to the population of visible features in the Noachian, it would suggest that the underlying terrain is Noachian in age. The buried craters can then be compared to visible Noachian craters to reveal the amount of deterioration of the buried features. These comparisons allow us to explore the morphology of the terrain in the Hesperian region to determine if topographic variations are due to differences in the thickness of the overlying material or are a characteristic of the underlying terrain. Procedure: Data collected by MOLA was analyzed using Gridview, a program developed at God-dard specifically for use with topographic data sets. The program enables the user to apply color stretches in order to accentuate subtle differences in topography. It can also convert data from a color image to a profile plot allowing the user to see quantitatively the variations in surface structure. Using such tools, 495 impact features greater than 15 km in diameter, both visible and buried, were found and recorded in nearly 8 million square kilometers of the Martian surface. The features were then marked as either visible or buried based …