Vilmos Steinmann: Estimating the formation time of the Martian valley network
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szeptember 24.
2021
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Lóczy Dénes
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Most of the Martian river valleys were formed in the early period of the planet, approximately 3.8 billion years ago., at the boundary of the Noachian - Hesperian epoch. Although the morphology of the valleys is well known, there are many unanswered questions about their origin, which may not only answer the morphological questions but also about the climatic conditions of the time.
I my study, I investigated an average-looking Martian valley (Tinto-B, 2°55’ S, 111°53’ E), ~81 km long and in addition I determined hydrological parameters for 100 equal sections that can be used to infer the velocity and the volume of the transported sediment and estimated time interval of formation. The study use the following dataset: a 50 m/px (meters/pixel) resolution DTM (Digital Terrain Model) from HRSC (High Resolution Stereo Camera), 6 m/px optical images from the CTX (Context Camera) and 100 m/px resolution infrared images from the THEMIS (Thermal Emission Imaging System) TI (Thermal Inertia) camera. The latter was used to estimate the sediment size of the valley bedrock [1], and the resulting shear stress and Shield coefficient. The CTX images and the DTM were used to define and delineate the valley walls. Estimation of the formation intervall of each section is based on the sediment transport rate developed by Meyer-Peter and Muller [2], which can be combined with the age estimation data, based on the crater size distribution. In this study, the shape of the valley was approximated as a trapezoid and the hydrological parameters, such as the rate of transport of sediment, were determined for each section [3]. For the grain size analysis, sampling was performed from the valley walls, which best represent the valley bedrock. The aim of this study is to estimate the formation interval and physical parameters of the predefined sections of the valley and to compare them with existing morphological and hydrological results based on the preliminary erosion-accumulation model [4].
