L’histoire géologique récente de Mars reste peu étudiée, comparativement à l’histoire « primitive » de Mars (>3,5 Ga). Cependant, l’arrivée de nouvelles images haute résolution a permis d’identifier la présence de ravines à la surface de terrains très récents. Dans ce travail, nous nous sommes attaché à caractériser la morphologie des ravines et les processus qui les ont générés. Ces nouvelles observations relancent la question de la présence d’eau liquide actuellement à la surface de Mars que ce soit à l’état pur ou sous forme de mélange (saumure, coulée de débris...). Des simulations expérimentales en chambre froide à la pression atmosphérique de Mars et de la Terre ont été menées. Elles ont notamment permis de quantifier le rôle de la teneur en eau dans la couche active du pergélisol sur le mécanisme de formation des ravines et leur mobilité. Nous avons également décrit l’évolution saisonnière de petits réseaux ramifiés qui se sont développés chaque année au printemps durant la période 2007-2012. / The recent geological history of Mars remains poorly studied, in comparison to theearly history of Mars (>3,5 Ga). However, the acquisition of new high-resolution imagesallowed to identified the presence of gullies on the surface of recent landforms such asdunes. In this work, we focused on characterizing the morphology of gullies and theirprocess(es) of formation. These new observations revive the issue of the presence of liquid water present on the surface of Mars than either pure or as a mixture (brine, debris flow ...). Experimental simulations in a cold room at Martian and terrestrial atmospheric pressure have been conducted. In particular, they allowed us to quantify the role of water content in the active layer of the permafrost in order to better constrain the mechanism of formation of gullies and their motion. We also described the seasonal evolution of small branched networks developed at spring during the 2007-2012 period.

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-09-05T19:55:41Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lomanto_zogaib_neves.pdf: 8358673 bytes, checksum: 9f42efc6634c0b49d194cc2a19630c84 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-09-18T17:00:26Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lomanto_zogaib_neves.pdf: 8358673 bytes, checksum: 9f42efc6634c0b49d194cc2a19630c84 (MD5) / Made available in DSpace on 2017-09-18T17:00:26Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lomanto_zogaib_neves.pdf: 8358673 bytes, checksum: 9f42efc6634c0b49d194cc2a19630c84 (MD5) Previous issue date: 2017 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O Cerrado ? considerado um hotspot mundial de biodiversidade, por apresentar uma vasta abund?ncia de esp?cies end?micas que sofrem uma anormal perda de habitat. Al?m disso neste bioma h? importantes bacias hidrogr?ficas, cuja preserva??o das nascentes e leito dos rios e c?rregos ? de extrema necessidade. Com a finalidade de facilitar o estudo dessas ?reas a utiliza??o do Sensoriamento Remoto tornou-se uma excelente ferramenta. Assim, num primeiro momento, este trabalho utilizou imagens dos sensores dos sat?lites Landsat-5 e Landsat-8 para monitorar o desenvolvimento de ?reas de degrada??o, utilizando o ?ndice NDVI, na sub-bacia Hidrogr?fica do Ribeir?o Chiqueiro entre 1984 e 2016. No segundo momento verificou a aplicabilidade das imagens do sat?lite CBERS-4 na distin??o de diferentes tipos de vegeta??o e ou uso e ocupa??o do terreno, comparando-o com o sat?lite Landsat-8, e Rapideye-3, por meio do ?ndice NDVI e da diferen?a NDVI. Como resultados da primeira parte do trabalho foi poss?vel quantificar 108 vo?orocas na regi?o e atestar que a ?rea da sub-bacia sofreu grandes mudan?as nos anos estudados, principalmente com aumento expressivo do uso e ocupa??o do terreno. Nas ?reas de entorno das vo?orocas, que tinham como predomin?ncia tipos de vegeta??o com menor densidade de dossel, como cultura agropecu?rias (principalmente pasto), Campo limpo e Campo Sujo, verificou-se uma maior tend?ncia de crescimento dos vo?orocamentos. Na segunda parte do trabalho foi poss?vel verificar que, como j? era esperado, as imagens do sensor do sat?lite Rapideye, apresentaram melhor resolu??o, sendo seguidas pela imagem do sensor do sat?lite CBERS-4, que se mostrou vi?vel para uso em ?reas de Cerrado. Mesmo assim, estas s?o preteridas por imagens do sensor do sat?lite Landsat-8, que no presente trabalho obteve os piores resultados, deixando de identificar muitas diferen?as na vegeta??o. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The Cerrado is considered a global biodiversity hotspot due to the abundance of Endemic species that suffer a huge habitat loss. Besides in this biome there are important hydrographic basins, whose Preservation of springs, rivers and streams is of utmost importance. In order to facilitate the study of these areas, the use of Remote Sensing has become an excellent tool. Thus, in the first stage, this work used images from the Landsat-5 and Landsat-8 satellite sensors to monitor the development of degradation areas, using the NDVI index, in the sub-basin of Ribeir?o Chiqueiro between 1984 and 2016. In the second The results obtained in this study show the applicability of the CBERS-4 satellite images to the distinction between different vegetation types and or use and occupation of land, comparing it with the satellite Landsat-8 and Rapideye-3, using the NDVI index and the NDVI difference. As a result of the first part, it was possible to quantify 108 gullies in the region attesting that the sub-basin area underwent major changes in the years studied, mainly with a significant increase in use and occupation of land. In the areas surrounding the gullies, which had as predominant types of vegetation with lower canopy density, such as agricultural culture (mainly pasture), Campo Limpo and Campo Sujo, there was a greater tendency of vo?orocamentos growth. In the second part of the work, it was possible to verify that, as expected, the images of Rapideye satellite sensor presented better resolution and were followed by the CBERS-4 satellite image, which proved to be feasible for use in Cerrado areas. Even so, these are neglected by images of the Landsat-8 satellite sensor, which in the present work obtained the worst results, failing to identify many differences in vegetation.