Search results for "TECTONICS"
showing 10 items of 385 documents
The importance of fracture-healing on the deformation of fluid-filled layered systems
2014
International audience; Understanding the fracturingehealingerefracturing cycle is a fundamental part of studying the deformation dynamics and the permeability evolution of rock systems. Previous studies, however, have not examined the influence of healing i.e. fracture-closure through vein formation and the mechanical properties of the " healed " fractures (veins) on the rock deformation. We present results from a two-dimensional coupled hydro-mechanical model which simulates large time and spatial scale dynamic fracturing and healing of a porous medium under the influence of gravity, tectonic stretching and elevated fluid pressures. Our results show that healing decreases the local porosi…
New lithostratigraphy for the Cantabrian Mountains: A common tectono-stratigraphic evolution for the onset of the Alpine cycle in the W Pyrenean real…
2019
The Pyrenean-Cantabrian Orogen arose through the collision of the Iberian and Eurasian plates, mostly in Cenozoic times. This orogen comprises two main mountain ranges, the Pyrenees to the east, and the Cantabrian Mountains to the west. To date, the early Alpine tectono-sedimentary phases preserved in the Cantabrian Mountains, of Permian and Triassic age, have been considered independently from the same phases in neighbouring basins of SW Europe, and even from the eastern part of the same orogeny (the Pyrenean orogeny). In consequence, the beginning of the Alpine cycle in the Cantabrian Mountains has been interpreted within a specific geodynamic context, far from the general evolutionary ph…
Geochemical investigations of submarine volcanic exhalations to the east of Panarea, Aeolian Islands, Italy
1991
Abstract Results are presented on scubadiving investigations carried out on thermal manifestations in the area of Panarea (Aeolian Islands). The area investigated falls inside a caldera which extends from the main island to the group of islets located to the northeast. The distribution of the gaseous manifestations is regulated by the NE-SW, NW-SE and N-S regional tectonic directrices, through which the more recent basic magma intruded, giving rise to dikes and pillow lavas. f O 2 -temperature relation of the gases sampled in the investigated area was calculated to be: log f O 2 = 11−24,593/ T which indicates that a buffering mechanism acted on the gases as they cooled down during their asc…
The Santa Ninfa Cave (Belice Valley): hydrogeochemical features and relationships with neotectonics
2020
The Santa Ninfa Cave (SNC) develops in an outcrop of Messinian gypsum, located in the heart of the zone struck by the 1968 seismic sequence of the Belice valley. It is composed of different levels of sub-horizontal galleries, the lowest of which is characterized by perennial flowing water, running along the water table. From the hydrogeological point of view, it configures as an open circuit, both inflowing and outflowing from/to neighboring aquifers. The geochemical facies of groundwater collected in the SNC is compatible with a meteoric recharge chemically interacting with evaporitic deposits. The most relevant geochemical feature is the mixing between a small tributary of sulfur water wi…
The Leiza palaeo-fault: Role and importance in the Upper Cretaceous sedimentation and palaeogeography of the Basque Pyrenees (Spain)
1999
Abstract New analysis of the Upper Cretaceous deposits of the Central Depression, a syncline within the Basque Pyrenees, shows that this structure was a deep marine basin analogous to the regional flysch troughs. It was bounded by active faults, including the Leiza palaeo-fault, which sustained erosion of the partly subaerially exposed margins. The Leiza palaeo-fault and its western counterpart, the Kalamua palaeo-fault, are thought to constitute the former plate boundary between Iberia and Europe, and a westward continuation of the North Pyrenean Palaeo-Fault.
The Foundation Seamount Chain: A first survey and sampling
1997
The Foundation Seamounts form a 1400 km-long chain on the Pacific plate from 32 °S, 127 °W to the Pacific-Antarctic spreading axis at 38 °S, 111 °W. Previously only known from sparse single-beam echosoundings and satellite altimetry, we present here the first multibeam bathymetric survey and geological sampling results. We confirm that the submarine topography correlates with the altimetry, and that the chain is volcanic rather than tectonic or microcontinental in origin. The chain can be divided up morphologically and geochemically into three section: (1) west of 125 °W large flat-topped volcanoes composed of incompatible-element depleted lavas ( ≈ 1) of a near-ridge origin with little or …
Palaeomagnetism of the central Cuban Cretaceous Arc sequences and geodynamic implications
2009
Abstract A detailed palaeomagnetic study of Cretaceous age volcanic and sedimentary arc rocks from central Cuba has been carried out. Samples from 32 sites (12 localities) were subjected to detailed demagnetisation experiments. Nineteen sites from the Los Paso, Matagua, Provincial and Cabaiguan Formations yielded high unblocking temperature, dual polarity directions of magnetisation which pass the fold tests with confidence levels of 95% or more and are considered to be primary in origin. The palaeomagnetic inclinations are equivalent to palaeolatitudes of 9°N for the Aptian, 18°N for the Albian. A synfolding remanence identified in 5 sites from the younger Hilario Formation indicates a lat…
The Palaeomagnetism of the Permian Rocks of the Black Forest, Germany
1972
Summary Palaeomagnetic measurements made upon Permian samples from the Black Forest, Odenwald and Pfalzerwald (excluding those measurements on samples from the Schopfheim basin) are consistent with those from north-western Europe. The virtual pole based upon 18 sites is 174.9°E. 48.4N. The measurements made on the fine-grained shales and mudstones from the Schopfheim basin are significantly different from the preceding. Since incorrect age assignment, sampling, components of secondary magnetic and tectonic effects can be excluded, the difference is attributed to incomplete removal of the effects of secular variation. The Scharfenstein massif previously regarded as Permian, was found to have…
Subduction of the Nazca Ridge and the Inca Plateau: Insights into the formation of ore deposits in Peru
2005
A large number of ore deposits that formed in the Peruvian Andes during the Miocene (15-5 Ma) are related to the subduction of the Nazea plate beneath the South American plate. Here we show that the spatial and temporal distribution of these deposits correspond with the arrival of relatively buoyant topographic anomalies, namely the Nazca Ridge in central Peru and the now-consumed Inca Plateau in northern Peru, at the subduction zone. Plate reconstruction shows a rapid metallogenic response to the arrival of the topographic anomalies at the subduction trench. This is indicated by clusters of ore deposits situated within the proximity of the laterally migrating zones of ridge subduction. It …
Pattern and rate of post-20 ka vertical tectonic motion around the Capo Vaticano Promontory (W Calabria, Italy) based on offshore geomorphological in…
2014
The magnitude and rate of Late Pleistocene-Holocene vertical tectonic movements offshore of the Capo Vaticano Promontory (western Calabria, southern Italy) have been measured on the basis of the present-day depth variations of the edges of submerged depositional terraces (and associated abrasion platforms) that formed below the storm-wave base, during the sea level stillstand of the Last Glacial Maximum (LGM). These depositional features, represented by submerged prograding wedges and an associated terrace-shaped upper boundary, have been identified in high-resolution seismic reflection profiles acquired along the continental shelf and the upper slope of the promontory, and are referred to …