Pit crater and pit crater chains associated to the volcano Arsia Mons on Mars have been mapped to analyse their spatial pattern and to conclude about their formation. For the mapping, high resolution satellite data gathered during the Mars Express mission were used. The spatial distribution of the pit craters was then compared with typical patterns of magmatic sheet intrusions within volcanoes as they are known from Earth. The results show that the pattern of the mapped pit craters and pit crater chains are in good agreement with these sheet intrusions and are therefore likely related to Martian sheet intrusions. / Kollapskratrar och kraterkedjor relaterade till vulkanen Arsia Mons på Mars har karterats för att analysera deras spatiala mönster och för att komma till slutsatser för deras tillblivelse. Högupplösta satellitbilder tagna av Mars Express-sonden har använts för karteringen. Fördelningen av de karterade kraterkedjorna jämfördes med typiska fördelningar av magmatiska gångbergarter från vulkaner på jorden. Resultaten visar att fördelningen av kollapskratrar och kraterkedjor överensstämmer enligt förväntningarna och påvisar en relation mellan kollapskratrar och magmatiska gångbergarter på Mars.

Mars est un objet privilégié pour comprendre l'évolution d'une planète. Des témoins géologiques de son activité interne et des échanges surface-atmosphère sont préservés sur 4 Ga. Cette thèse étudie ces échanges au travers de la circulation des fluides dans la croûte. Le climat froid et sec de l'Amazonien (< 3 Ga) implique la condensation, sublimation et diffusion des espèces volatiles dans le régolithe. Ce paradigme est modifié par la découverte de l'importance de la convection d'air dans les sols poreux (aérothermalisme). Ce processus a été mis en évidence par l'imagerie thermique (Mars Odyssey/THEMIS) et la morphologie (e.g., Mars Express/HRSC) pour Cerberus Fossae et le volcan Arsia Mons. La période Hespérienne est marquée par la libération massive d'eau aboutissant à la formation des terrains chaotiques et des chenaux de débâcle. Nous proposons que ces objets résultent de la convection d'argiles. Cette hypothèse originale est corroborée par les détections de phyllosilicates (données CRISM et OMEGA).

Recurrence rate is often used to describe volcanic activity. There are numerous documented ex- amples of non-constant recurrence rate (e.g. Dohrenwend et al., 1984; Condit and Connor, 1996; Cronin et al., 2001; Bebbington and Cronin, 2011; Bevilacqua, 2015), but current techniques for calculating recurrence rate are unable to fully account for temporal changes in recurrence rate. A local–window recurrence rate model, which allows for non-constant recurrence rate, is used to calculate recurrence rate from an age model consisting of estimated ages of volcanic eruption from a Monte Carlo simulation. The Monte Carlo age assignment algorithm utilizes paleomagnetic and stratigraphic information to mask invalid ages from the radiometric date, represented as a Gaussian probability density function. To verify the age assignment algorithm, data from Heizler et al. (1999) for Lathrop Wells is modeled and compared. Synthetic data were compared with expected results and published data were used for cross comparison and verification of recurrence rate and volume flux calculations. The latest recurrence rate fully constrained by the data is reported, based upon data provided in the referenced paper: Cima Volcanic Field, 33 +55/-14 Events per Ma (Dohren- wend et al., 1984), Cerro Negro Volcano, 0.29 Events per Year (Hill et al., 1998), Southern Nevada Volcanic Field, 4.45 +1.84/-0.87 (Connor and Hill, 1995) and Arsia Mons, Mars, 0.09 +0.14/-0.06 Events per Ma (Richardson et al., 2015). The local–window approach is useful for 1) identifying trends in recurrence rate and 2) providing the User the ability to choose the best median recurrence rate and 90% confidence interval with respect to temporal clustering.