Search results for "Outcrop"
showing 10 items of 101 documents
Soils of Eagle crater and Meridiani Planum at the Opportunity Rover landing site.
2004
The soils at the Opportunity site are fine-grained basaltic sands mixed with dust and sulfate-rich outcrop debris. Hematite is concentrated in spherules eroded from the strata. Ongoing saltation exhumes the spherules and their fragments, concentrating them at the surface. Spherules emerge from soils coated, perhaps from subsurface cementation, by salts. Two types of vesicular clasts may represent basaltic sand sources. Eolian ripples, armored by well-sorted hematite-rich grains, pervade Meridiani Planum. The thickness of the soil on the plain is estimated to be about a meter. The flatness and thin cover suggest that the plain may represent the original sedimentary surface.
Predicting the landslides triggered by the 2009 96E/Ida tropical storms in the Ilopango caldera area (El Salvador, CA): optimizing MARS-based model b…
2019
The main topic of this research was to evaluate the effect in the performance of stochastic landslide susceptibility models, produced by differences between the triggering events of the calibration and validation datasets. In the Caldera Ilopango area (El Salvador), MARS (multivariate adaptive regression splines)-based susceptibility modeling was applied using a set of physical–environmental predictors and two remotely recognized landslide inventories: one dated at 2003 (1503 landslides), which was the result of a normal rainfall season, and one which was produced by the combined effect of the Ida hurricane and the 96E tropical depression in 2009 (2237 landslides). Both the event inventorie…
Ladinian carbonates of the Cabo Cope Unit (Betic Cordillera, SE Spain): a tethys-maláguide palaeogeographic gateway.
2003
7 pages, 4 figures.
A foraminiferal assemblage as a bioevent marker of the main Ladinian transgressive stage in the Betic Cordillera, southern Spain
2005
Abstract The Betic Cordillera comprises the mountain range in the southern Iberian Peninsula that extends from Cadiz to Alicante, which displays typical features of alpine cordilleras. The Betic Cordillera includes two large geological tectonic domains, namely an External Zone, and an Internal Zone. The External Zone is essentially composed of epicontinental Triassic rocks that consist of the Buntsandstein, Muschelkalk and Keuper facies. The Buntsandstein facies rarely occur in outcrops, whereas the Keuper stratigraphic successions are truncated. The Muschelkalk facies frequently displays complete successions that are very useful for interpreting the Ladinian stage palaeogeography. The Musc…
Characterization and correlation of Upper Jurassic (Oxfordian) bentonite deposits in the Paris Basin and the Subalpine Basin, France
2003
Explosive volcanic activity is recorded in the Upper Jurassic of the Paris Basin and the Subalpine Basin of France by the identification of five bentonite horizons. These layers occur in Lower Oxfordian (cordatum ammonite zone) to Middle Oxfordian (plicatilis zone) clays and silty clays deposited in outer platform environments. In the Paris Basin, a thick bentonite (10–15 cm), identified in boreholes and in outcrop, is dominated by dioctahedral smectite (95%) with trace amounts of kaolinite, illite and chlorite. In contrast, five bentonites identified in the Subalpine Basin, where burial diagenesis and fluid circulation were more important, are composed of a mixture of kaolinite and regular…
Two-dimensional apparent microfabric of the basal Late Weichselian till and associated shear zone: case study from western Latvia
2008
The examination of glacial sediments in thin sections has become a common procedure in recent years. Apparent sand grain orientation (microfabric) in thin sections is one of the key elements marking certain microstructures. In an attempt to make till micromorphology studies less subjective and investigate the orientation of sand-sized particles in tills, we have developed an image analysis procedure to measure and analyse the spatial distribution of the till microfabric. We studied 13 thin sections of the Weichselian subglacial till and basal shear zone outcropping in the Baltic Sea bluffs at the Ziemupe site in western Latvia. The results were visualized as a two-dimensional grid of rose d…
Stratigraphic and structural relationships between Meso-Cenozoic Lagonegro basin and coeval carbonate platforms in southern Apennines, Italy
1999
Abstract Stratigraphic studies and facies analysis integrated with a new geological and structural survey of the Meso-Cenozoic units outcropping in the Campania–Lucania Apennines, southern Italy, allowed us to restore the palaeogeographic pattern and the tectonic evolution of the chain during Oligo-Miocene times. The southern Apennines are a N150°-striking and NE-verging fold-and-thrust belt mainly derived from the deformation of the African–Apulian passive margin. Four wide belts with different features have been recognized in the chain area. From east to west the following units outcrop: (a) successions characterized by basinal to marginal facies, ranging in age from Cretaceous to Miocene…
Tectono-sedimentary constraints to the Oligocene-to-Miocene evolution of the Peloritani thrust belt (NE Sicily)
1999
Abstract The Peloritani thrust belt belongs to the southern sector of the Calabrian Arc and is formed by a set of south-verging tectonic units, including crystalline basement and sedimentary cover (from the top: Aspromonte U.; Mela U.; Mandanici U.; Fondachelli U.; Longi-Taormina U.), piled up starting from Late Oligocene. At least two main terrigenous clastic formations lie with complicated relationships on top of the previous units: the Frazzano Fm (Oligocene) and the Stilo-Capo d'Orlando Fm (Late Oligocene?–Early Miocene), as syn-to-post-tectonic deposits. These clastic deposits have different characteristics, in space and time, representing or flysch-like sequences involved in several t…
Sedimentary dynamics and structural geology of pre-rift deposits of the interior basin of Gabon
2002
Abstract Recent studies combining field data (facies and paleocurrent analyses, structural surveys), sub-surface data (core analyses, well logs, seismic sections) and palynological data provide insight into the sedimentary dynamics of pre-rift deposits of the interior basin of Gabon and their structural and paleoclimatic setting. These sedimentary deposits belong to the Noya, Agoula and M’vone series of Late Precambrian to Jurassic age. Although these deposits are potential sources of petroleum, they are partly known because of poor outcrop in a wet equatorial climate, low density and uneven distribution of exploration wells and poor seismic survey coverage. The pre-rift deposits reflect fl…
Sicilian Lithostratigraphic Units
2018
This chapter includes the description of the Sicilian lithostratigraphic units (Fig. 2.1). They are grouped in a generally chronological order and the complete list of the worksheets is shown in the Table of contents. In each chronologic group the worksheets of the described formations are organized in alphabetic order. The Permo-Triassic units are the oldest deposits outcropping in Sicily that originated during the early stages of the Southern Tethyan continental rifting. The Meso-Cenozoic carbonate units represent the sedimentary sequences of the various stratigraphic successions differentiated in the field along the Sicilian outcrops. The deposits of the Sicilide Complex (Tethyan units) …