STRUCTURAL ANALYSIS, LAYER THICKNESS MEASUREMENTS AND MINERALOGICAL INVESTIGATION OF THE LARGE INTERIOR LAYERED DEPOSIT WITHIN GANGES CHASMA, VALLES MARINERIS, MARS

The interior layered deposit (ILD) in Ganges Chasma, Valles Marineris, is a 4.25 km high mound that extends approximately 110 km from west to east. The deposition, deformation, and erosion history of the Ganges ILD records aids in identifying the processes that formed and shaped the Chasma. To interpret structural and geomorphic processes acting on the ILD, multiple layer attitudes and layer thickness transects were conducted on the Ganges ILD. Mineralogical data was analyzed to determine correlations between materials and landforms. Layer thickness measurements indicate that the majority of layers are between 0.5 m and 4 m throughout the ILD. Three major benches dominate the Ganges ILD. Layer thicknesses increase at the ILD benches, suggesting that the benches are formed from the gradual thickening of layers. This indicates that the benches are depositional features draping over basement topography. Layer attitudes indicate overall shallow dips generally confined to a North-South direction that locally appear to follow bench topography. Layering is disrupted on a scale of 40 m to 150 m in 12 separate locations throughout the ILD. In all locations, underlying layering is disturbed by overlying folded layers in a trough-like geometry. These features are interpreted to have formed as submarine channels in a lacustrine setting, subsequently infilled by sediments. Subsequently, the channels were eroded to the present topography, resulting in the thin, curved layering observed. Data cannot conclusively support one ILD formation hypothesis, but does indicate that the Ganges ILD postdates Chasma formation. The presence of water altered minerals, consistently thin layering, and layer orientations provide strong evidence that the ILD formed in a lacustrine setting.

Geology of Hebes Chasma, Valles Marineris, Mars

Hebes Chasma is an 8 km deep, 126 by 314 km, isolated basin that is partially filled with interior layered deposits (ILD), massive deposits of water altered strata. By analyzing the ILD’s structure, stratigraphy and mineralogy, as well as the perimeter faults exposed in the plateau adjacent to the chasma, the evolution and depositional history of Hebes Chasma is interpreted. Three distinct ILD units were found and are informally referred to as the Lower, Upper and Late ILDs. These units have differing layer thicknesses, layer attitudes, mineralogies and erosional landforms. Based on observations of the plateau, wall morphology and slump blocks within the chasma’s interior, chasma evolution appears to be controlled by cross-faults that progressively detached sections of the wall. A scenario involving the loss of subsurface volume and ash fall events is proposed as the dominant setting throughout Hebes’ geologic history.

Structural analysis of interior layered deposits in north and south Coprates Chasma, Mars

Interior layered deposits within an embayment in the northern as well as near the southern wall of Coprates Chasma in the Valles Marineris, Mars are studied using HRSC, CTX, HiRISE and CRISM data. In the northern embayment, layered deposits outcrop in three separate locations (a western deposit, a central deposit and an eastern deposit). The central layered deposit in the north has a stratigraphic thickness of 2 km. The western layered deposit abuts against the chasma wall appearing to have a relatively un-eroded depositional surface. The eastern deposit is near a landslide scar which appears to have exposed basement layering showing downward displacement. This northern embayment is suggested to have been an ancestral basin. The triangular edged deposit near the southern wall of Coprates Chasma has an elongated mound protruding from the central edge and is suggested to be the outer limits of a fault block which is back rotated 6° south. The rotation may be the result of the Valles Marineris opening.

Recurring slope lineae in equatorial regions of Mars

The presence of liquid water is a requirement of habitability on a planet. Possible indicators of liquid surface water on Mars include intermittent flow-like features observed on sloping terrains. These recurring slope lineae are narrow, dark markings on steep slopes that appear and incrementally lengthen during warm seasons on low-albedo surfaces. The lineae fade in cooler seasons and recur over multiple Mars years. Recurring slope lineae were initially reported to appear and lengthen at mid-latitudes in the late southern spring and summer and are more common on equator-facing slopes where and when the peak surface temperatures are higher. Here we report extensive activity of recurring slope lineae in equatorial regions of Mars, particularly in the deep canyons of Valles Marineris, from analysis of data acquired by the Mars Reconnaissance Orbiter. We observe the lineae to be most active in seasons when the slopes often face the sun. Expected peak temperatures suggest that activity may not depend solely on temperature. Although the origin of the recurring slope lineae remains an open question, our observations are consistent with intermittent flow of briny water. Such an origin suggests surprisingly abundant liquid water in some near-surface equatorial regions of Mars.

Mémoire relatif à la carte des vallées d'Aspe, d'Ossau, d'Asson, d'Azun et Barretous, dans les montagnes des Pirennées, depuis Oleron jusques aux vallées de Canfran, et de Biescas frontiere de l'Arragon, visitées, et corrigées par M.rs d'Arnou, et Touros dans le mois de 7.bre 1753

Ancien possesseur : Argenson, Antoine-René de Voyer (1722-1787 ; marquis de Paulmy d')

Ecología del paisaje y sistemas de información geográfica ante el cambio socioambiental en las áreas de la montaña mediterránea. Una aproximación metodológica al caso de los valles d'Hortmoier y Sant Aniol

Este artículo es una aproximación a los métodos utilizados para analizar, cuantificar y valorar los cambios en los usos y cubiertas del suelo en estos dos valles que forman parte del espacio natural protegido de la Alta Garrotxa. La dinámica vivida en este territorio es un claro ejemplo de los procesos acaecidos a lo largo del siglo XX en buena parte de las áreas de montaña mediterránea. Una dinámica caracterizada fundamentalmentepor un incremento de la superficie forestal en detrimento del espacio agrario. Así mismo se proponen pautas metodológicas para su adecuada cartografía, así como para determinar las áreas potencialmente recuperables de espacio agrario con el objetivo de mantener la diversidad paisajística, biológica y el patrimonio cultural con la ayuda de los SIG y la Ecología del Paisaje

Inventaire des géomorphosites des vallées d'Entremont et de Ferret (Valais) et propositions de valorisation

Cet article présente les résultats d'un inventaire de géomorphosites, réalisé dans les vallées d'Entremont et de Ferret (Valais, Suisse). Les motivations de cette étude découlent d'un double constat : le patrimoine géomorphologique est d'une part souvent méconnu d'un public large et peu pris en compte dans les politiques d'aménagement du territoire ou de protection de la nature ; d'autre part, il possède un excellent potentiel de valorisation géotouristique. Pour améliorer la situation dans ces deux domaines, il est tout d'abord nécessaire de procéder à un état des lieux du patrimoine géomorphologique : notre démarche consiste dans un premier temps à identifier les géomorphosites parmi les nombreuses formes intéressantes du terrain d'étude, puis à les évaluer selon une méthodologie éprouvée. Nous proposons finalement des pistes pour mettre en valeur les géomorphosites. Nous cherchons en fait à déterminer dans quelle mesure l'outil de l'inventaire de géomorphosites peut contribuer à la mise en valeur du patrimoine géomorphologique

Los vertebrados fosiles del Abocador de Can Mata (els Hostalets de Pierola, l'Anoia, CataluÑa), una sucesion de localidades del Aragoniense superior (MN6 y MN7+8) de la cuenca del Valles-Penedes. CampaÑas 2002-2003, 2004-2005

Se presenta una síntesis del registro de vertebrados fósiles del Abocador de Can Mata (els Hostalets de Pierola, cuenca neógena del Vallès-Penedès), con especial énfasis en los aspectos taxonómico y bioestratigráfico. Este macroyacimiento incluye por el momento una sucesión de 91 localidades de micro- y/o macrovertebrados muestreadas, repartidas a lo largo de unos 300 m de serie estratigráfica, abarcando un intervalo de tiempo de más de un millón de años correspondiente al Aragoniense superior. Durante los 28 meses de trabajo de campo desarrollados a lo largo de las campañas 2002-2003, 2004 y 2005, se han recuperado más de 15.000 restos de macrovertebrados fósiles y más de 1.300 dientes de micromamíferos (cantidad que se verá incrementada en el futuro cuando haya finalizado el lavado y triado de los sedimentos acumulados). Se presenta por primera vez una lista exhaustiva del conjunto de localidades y su contextualización estratigráfica, además de una lista faunística actualizada y una propuesta de biozonación local. La gran riqueza fosilífera de la zona y el enorme esfuerzo de muestreo, combinados con los requerimientos de la legislación vigente sobre protección del patrimonio paleontológico, explican el éxito de la intervención paleontológica. En conjunto, la ampliación del vertedero de Can Mata, con el adecuado control paleontológico, proporciona una oportunidad única para investigar la composición faunística de los ecosistemas terrestres del Aragoniense superior en el suroeste de Europa.