Early magmatic processes on Mars

2021

This thesis investigates tectonic, volcanic and magmatic processes on Mars during the Noachian (< 3.7 Ga) and Hesperian (< 3.0 Ga) periods with the help of combined remote sensing techniques, high-resolution images and reflectance spectroscopy. A survey of magmatic dikes in eastern VallesMarineris has been conducted in order to constrain their number and extent in the Tharsis region. Magmatic dikes have been proposed to have weakened and fractured the crust, allowing the formation of Valles Marineris. Hence, this survey helped to understand the relationship of dike formation with Valles Marineris formation. Over a hundred dikes were identified. Estimation of magma eruption rates suggest that dikes alone may have fed the volcanic plains by successive fissure eruptions. Three distinct dike orientations are recorded: 70±, 90± and 110±, the latest being subparallel to VallesMarineris main trend. An east-west dichotomy is observed delimited by the Coprates Rise. 90± and 70± groups are observed to the east, group 110± is observed to the west. Surprisingly, other features have similar orientations, turning from 110± to 90± from west to east: pits chains and elongated troughs. This suggests they formed above dikes and/or under a similar stress regime. Ganges Chasma and a 400 km long wall segment of Coprates Chasma located east of the Coprates Rise are oriented 90±. It remains unclear if dikes controlled Valles Marineris opening but their formation appears to be closely related. The Coprates Rise is likely a limit between two crustal blocs that have undergone distinct and successive tectonic stress fields that led to dike emplacement, Chasmata opening and other small features formations. Impact crater central peaks were used as natural probes to constrain the Tharsis dome geometry, volume and age of formation of the bulk of the edifice. With HiRISE high-resolution images, two lithologies were identified in central peaks: dark-toned layers likely to represent stack of l

SDG 14 - Life Below Water; PhD-Thesis - Research and graduation internal

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