Etude morphologique de la formation des ravines sur les dunes martiennes (approche comparative Terre/Mars.)

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.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

New insights on the Sorbas Basin (SE Spain): the onshore reference of the Messinian Salinity Crisis

International audienceThe Sorbas Basin is the land reference of the Messinian Salinity Crisis (MSC) that affected the Mediterranean Sea in the latest Miocene. Its stratigraphy has been re-visited using calcareous nannofossils and planktonic foraminifers, which provide a reliable biostratigraphic frame and lead to particularly specify the relationships between the Sorbas and Zorreras members with Yesares evaporites.The evaporites overlie a shallowing upward sequence ending with the deposition of the Reef Unit and Terminal Carbonate Complex (TCC) on the periphery of the basin. The reefal carbonates of the TCC are overlain by clastic deposits that are foreset beds of post-MSC Gilbert-type fan deltas developed on the northern edge of the basin. These sedimentary structures are separated from reefal carbonates and the Reef Unit by the Messinian Erosional Surface (MES). The various facies of the Sorbas Member have been correlated with the bottomset beds of the Gilbert-type fan deltas despite some differences in palaeobathymetry. In the southeastern periphery of the basin, the MES separates the Sorbas Member from the Yesares gypsums. In the central part of the basin, a hiatus characterizes the contact between these members. The Zorreras Member postdates the MSC and entirely belongs to Zanclean. Its white “Lago Mare” layers are lagoonal deposits, the fauna of which is confirmed to result from Mediterranean–Paratethys high sea-level exchange after the post-MSC marine reflooding of the Mediterranean Basin.This study allows to re-assert the two-step scenario of the MSC (Clauzon et al., 1996) with the following events:- at 5.971–5.600 Ma, minor sea-level fall resulting in the desiccation of this peripheral basin with secondary fluctuations;- at 5.600–5.460 Ma, significant subaerial erosion (or lack of sedimentation) caused by the almost complete desiccation of the Mediterranean Sea;- instantaneous marine reflooding, accepted at 5.460 Ma, followed by continuing sea-level rise

New Insights on the Sorbas Basin (SE Spain): the onshore reference of the Messinian Salinity Crisis

The Sorbas Basin is the land reference of the Messinian Salinity Crisis (MSC) that affected the Mediterranean Sea in the latest Miocene. Its stratigraphy has been re-visited using calcareous nannofossils and planktonic foraminifers, which provide a reliable biostratigraphic frame and lead to particularly specify the relationships between the Sorbas and Zorreras members with Yesares evaporites. The evaporites overlie a shallowing upward sequence ending with the deposition of the Reef Unit and Terminal Carbonate Complex (TCC) on the periphery of the basin. The reefal carbonates of the TCC are overlain by clastic deposits that are foreset beds of post-MSC Gilbert-type fan deltas developed on the northern edge of the basin. These sedimentary structures are separated from reefal carbonates and the Reef Unit by the Messinian Erosional Surface (MES). The various facies of the Sorbas Member have been correlated with the bottomset beds of the Gilbert-type fan deltas despite some differences in palaeobathymetry. In the southeastern periphery of the basin, the MES separates the Sorbas Member from the Yesares gypsums. In the central part of the basin, a hiatus characterizes the contact between these members. The Zorreras Member postdates the MSC and entirely belongs to Zanclean. Its white "Lago Mare" layers are lagoonal deposits, the fauna of which is confirmed to result from Mediterranean-Paratethys high sea-level exchange after the post-MSC marine reflooding of the Mediterranean Basin. This study allows to re-assert the two-step scenario of the MSC (Clauzon et al., 1996) with the following events: - at 5.971-5.600 Ma, minor sea-level fall resulting in the desiccation of this peripheral basin with secondary fluctuations; - at 5.600-5.460 Ma, significant subaerial erosion (or lack of sedimentation) caused by the almost complete desiccation of the Mediterranean Sea; - instantaneous marine reflooding, accepted at 5.460 Ma, followed by continuing sea-level rise

Geomorphologic study of the dynamic of debris flow formation on Mars : comparative approach Earth / Mars

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

Étude morphologique de la formation des ravines sur les dunes martiennes : approche comparative Terre/Mars

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.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

Reply to the comment on the paper "Lago Mare and the Messinian Salinity Crisis: Evidence from the Alboran Sea (S. Spain) by Do Couto et al. (2014) Marine and Petroleum Geology 52 (57–76)" authored by Serrano and Guerra-Merchán

The marine context of the Lago Mare deposit near Malaga has received agreement as well as its ascription to the third Lago Mare event of Clauzon et al. (2005). This deposit is not a “transitional unit towards normal marine conditions” but followed the marine reflooding of the Mediterranean Basin, allowing the connection with the Dacic Basin (Eastern Paratethys). We show that this Lago Mare event did not result from a climatic change leading to a dilution episode but from a high sea-level connection. Different interpretations on the respective effects of tectonics and eustatism on the sedimentary archives linked to the Messinian Salinity Crisis (MSC) are once more debated. They depend on (1) the duration assigned to the MSC and its subdivisions, (2) the amplitude of the successive sea level variations, and at last (3) the dimensional (local or regional) view of the MSC. Such discrepancies concern subsidiary matters which cannot mask first order facts and progresses in their knowledge

New Insights on the Sorbas Basin (SE Spain): the onshore reference of the Messinian Salinity Crisis

The Sorbas Basin is the land reference of the Messinian Salinity Crisis (MSC) that affected the Mediterranean Sea in the latest Miocene. Its stratigraphy has been re-visited using calcareous nannofossils and planktonic foraminifers, which provide a reliable biostratigraphic frame and lead to particularly specify the relationships between the Sorbas and Zorreras members with Yesares evaporites. The evaporites overlie a shallowing upward sequence ending with the deposition of the Reef Unit and Terminal Carbonate Complex (TCC) on the periphery of the basin. The reefal carbonates of the TCC are overlain by clastic deposits that are foreset beds of post-MSC Gilbert-type fan deltas developed on the northern edge of the basin. These sedimentary structures are separated from reefal carbonates and the Reef Unit by the Messinian Erosional Surface (MES). The various facies of the Sorbas Member have been correlated with the bottomset beds of the Gilbert-type fan deltas despite some differences in palaeobathymetry. In the southeastern periphery of the basin, the MES separates the Sorbas Member from the Yesares gypsums. In the central part of the basin, a hiatus characterizes the contact between these members. The Zorreras Member postdates the MSC and entirely belongs to Zanclean. Its white "Lago Mare" layers are lagoonal deposits, the fauna of which is confirmed to result from Mediterranean-Paratethys high sea-level exchange after the post-MSC marine reflooding of the Mediterranean Basin. This study allows to re-assert the two-step scenario of the MSC (Clauzon et al., 1996) with the following events: - at 5.971-5.600 Ma, minor sea-level fall resulting in the desiccation of this peripheral basin with secondary fluctuations; - at 5.600-5.460 Ma, significant subaerial erosion (or lack of sedimentation) caused by the almost complete desiccation of the Mediterranean Sea; - instantaneous marine reflooding, accepted at 5.460 Ma, followed by continuing sea-level rise