Search results for "TECTONICS"
showing 10 items of 385 documents
Fan Deltas and Floodplains in Valencian Coastal Plains
2018
The Valencian coastal plains are formed at the end of two important mountain systems: the Iberian Mountain Range to the north and the Baetic Mountains to the south. As a result of tectonic and neotectonic activity, several graben have been formed at the foot of these reliefs, which have been filled with Plio-Quaternary deposits. In all the coastal plains a depositional sequence is repeated in which the river deposits -fan deltas and alluvial plains- alternate with lagoons/marshes. Basin dimensions, sediment input, tectonics and neotectonics in the study area all determine the size, style and characteristics of fluvial forms, which in turn, influence the characteristics of the coast. Ephemer…
Continental extension: From core complexes to rigid block faulting
2005
Extension of overthickened continental crust is commonly characterized by an early core complex stage of extension followed by a later stage of crustal-scale rigid block faulting. These two stages are clearly recognized during the extensional destruction of the Alpine orogen in northeast Corsica, where rigid block faulting overprinting core complex formation eventually led to crustal separation and the formation of a new oceanic backarc basin (the Ligurian Sea). Here we investigate the geodynamic evolution of continental extension by using a novel, fully coupled thermomechanical numerical model of the continental crust. We consider that the dynamic evolution is governed by fault weakening, …
Metamorphic and structural evolution of the Maures-Tanneron massif (SE Variscan chain): evidence of doming along a transpressional margin
2009
AbstractThe Variscan metamorphic and structural evolution of the Maures-Tanneron massif is divided in two main post-collisional phases: (1) a MP-MT regional gradient is developed during nappe-piling process between 350 and 320 Ma, followed by (2) LP-HT regional gradient coeval with doming between 320 and 300 Ma. During this late phase, the tectonic context was dominated by E-W shortening, which produced crustal-scale upright folds and major strike-slip displacement along trans-crustal faults. Symmetric extensional fabrics are observed on the limbs of crustal-scale anticlines, and are ascribed to local accommodation of lower crust exhumation. Heat and magma transfer are allowed by these larg…
A fault-related coalification anomaly in the Blanzy-Montceau Coal Basin (Massif Central, France)
1997
Abstract The Stephanian intramontane Blanzy-Montceau Coal Basin is situated along a Variscan fault complex bordering the Upper Paleozoic Blanzy-Le Creusot-Bert graben. The deposition of coal-bearing strata was controlled by a complex of early faults known as the “Faille de Bordure” (FB, Border Fault). Another complex of Permian faults known as the “Faille de l'Est” (FE, Eastern Fault) is situated along the more central part of the coal basin. Coalification in the basin follows three main trends: (1) Increasing rank from upper to lower coal seams in accordance with a general vertical trend (Hilt, 1873). The gradient of volatile matter is higher than normal, ranging from 3% to I I% Vdaf per 1…
Students' field research extends knowledge of origin of a UNESCO World Heritage site in Germany
2003
In 1992, as part of field-based course work with the Earth science department of the Universitat Minz, students began to investigate the structures of oil shale basins located in the Sprendlinger Horst, a horst-type block forming the northeastern shoulder of the Tertiary Upper Rhine Graben in southwestern Germany (figure 1). The Sprendlinger Horst is mainly built up by Hercynian or pre-Hercynian basement, Permian sediments, and volcanic rocks, as well as by several Tertiary alkali basalts and rare Cretaceous trachytes. In 1992, it was unknown whether the oil shale basins were of tectonic, volcanic, or even of impact origin.
Tectonic beheading of fluvial valleys in the Maestrat grabens (eastern Spain): Insights into slip rates of Pleistocene extensional faults
2013
Abstract Interaction between faulting and landscape evolution in regions of active tectonics allows us to use subtle geomorphological markers for estimating fault slip rates. Geomorphic features of two valleys connected with the bottom of the Alcala de Xivert graben, at the Maestrat graben system (eastern Spain), suggest that they correspond to the lowest segments of ancient valleys whose original heads were located at the axis of the neighbouring Irta range. They were beheaded owing to displacement of the Torreblanca and Irta faults during a period of active extensional faulting in Middle Pleistocene times. These faults produced a negative inversion of the relief, sinking a narrow graben (…
Vertical movements in NE Sicily and its offshore: Outcome of tectonic uplift during the last 125 ky
2013
New data in the coastal area between Acquedolci and Patti (northeastern Sicily, Italy) have been collected to calculate vertical tectonic rates in a key sector between the Kabilian-Calabrian and the Sicilian-Maghrebian chain. The comparison among marine geology data (multibeam and seismic reflection profiles) on the continental shelf-slope system and the radiocarbon ages on geomorphological markers collected during a coastal survey, provided new stratigraphic, geomorphological and biological data, contributing to the knowledge of the geological evolution of this sector for the last 125 ky.This coastal area is framed between two main structural features active during the Pleistocene in north…
Middle-Late Pleistocene marine terraces and fault activity in the Sant’Agata di Militello coastal area (north-eastern Sicily)
2012
Abstract The coastal sector of Sant’Agata di Militello (north-eastern Sicily) is characterized by a flight of raised Middle-Upper Pleistocene marine terraces occurring at different heights with respect to present sea level. In particular, the geomorphological survey and the analysis of stereo-pairs of aerial photographs allowed to recognize at least five main orders of well preserved Quaternary surfaces and relative deposits mostly located at the hanging wall and at the footwall of the Pleistocene northwest-dipping Capo d’Orlando normal fault, which controlled the geomorphological evolution of the coastal area. The marine terraces show an overall good morphological continuity and are formed…
Tectonic and lithological constraints on the evolution of the Karoo graben of northern Malawi (East Africa)
1995
The results of a lithostratigraphic, tectonic and kinematic study of the Karoo deposits of northern Malawi are reported. The objective of the lithostratigraphic study is to correlate the deposits of the Karoo basins of northern Malawi with the well-known deposits of southern Tanzania, thus establishing a stratigraphic framework through which the timing of faulting can be constrained. The kinematic analysis of faulting constrains the opening direction for the Karoo graben in this area and provides basic data to discuss the Karoo graben development within the regional tectonic framework of south-eastern Africa. The studied adults are defined by moderately to steeply dipping cataclastic zones …
Fault-controlled Soil CO2 Degassing and Shallow Magma Bodies: Summit and Lower East Rift of Kilauea Volcano (Hawaii), 1997
2006
Soil CO2 flux measurements were carried out along traverses across mapped faults and eruptive fissures on the summit and the lower East Rift Zone of Kilauea volcano. Anomalous levels of soil degassing were found for 44 of the tectonic structures and 47 of the eruptive fissures intercepted by the surveyed profiles. This result contrasts with what was recently observed on Mt. Etna, where most of the surveyed faults were associated with anomalous soil degassing. The difference is probably related to the differences in the state of activity at the time when soil gas measurements were made: Kilauea was erupting, whereas Mt. Etna was quiescent although in a pre-eruptive stage. Unlike Mt. Etna, fl…