Search results for "Tectonic"
showing 10 items of 470 documents
Active geodynamics of the central Mediterranean Sea: Tensional tectonic evidences in western Sicily from mantle-derived helium
2005
[1] We report results on the measured high 3He/4He isotope ratio in western Sicily, interpreted together with the heat data. The study of this sector of the Europe-Africa interaction is crucial to a better understanding of the tectonics and the geodynamical evolution of the central Mediterranean area. The estimated mantle-derived helium fluxes in the investigated areas are up to 2–3 orders of magnitude greater than those of a stable continental area. The highest flux, found in the southernmost area near the Sicily Channel, where recent eruptions of the Ferdinandea Island occurred 20 miles out to sea off Sciacca, has been associated with a clear excess of heat flow. Our results indicate that…
Precambrian crustal evolution and continental drift
1981
One of the major questions of Precambrian research is whether present-day plate tectonic models can be applied to the evolution of the ancient continental crust or whether the tectonic style suggests a unidirectional and therefore non-uniformitarian development in response to gradual changes in the global thermal regime through time.
A strike-slip core complex from the Najd fault system, Arabian shield
2014
Metamorphic core complexes are usually thought to be associated with regional crustal extension and crustal thinning, where deep crustal material is exhumed along gently dipping normal shear zones oblique to the regional extension direction. We present a new mechanism whereby metamorphic core complexes can be exhumed along crustal-scale strike-slip fault systems that accommodated crustal shortening. The Qazaz metamorphic dome in Saudi Arabia was exhumed along a gently dipping jog in a crustal-scale vertical strike-slip fault zone that caused more than 25 km of exhumation of lower crustal rocks by 30 km of lateral motion. Subsequently, the complex was transected by a branch of the strike-sli…
Ecological implications of Cousinia Cass. (Asteraceae) persistence through the last two glacial–interglacial cycles in the continental Middle East fo…
2012
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Crust Formation and Plate Motion in the Early Archean
1992
Mounting evidence for voluminous continental crust formation in the early Archean involving intracrustal melting and selective preservation of granitoid rocks suggests that initial crust formation crust formation and growth were predominantly by magmatic underplating in plumegenerated Iceland-type settings. Collision of these early islands to give rise to larger blocks is suggested by extensive horizontal shortening in both supracrustal and granitoid assemblages. Preservation of early Archean high-grade gneisses that were once at depths of 20 to 30 kilometers implies that these blocks developed thick, subcrustal roots despite high mantle heat flow. Rigid continental plates must have existed…
A new concept of continental construction in the Central Asian Orogenic Belt
2011
A new concept of continental construction based on four main terms: (1) crustal growth, (2) crustal formation, (3) continental growth and (4) continental formation is presented here. Each of these terms reflects a certain process responsible for the formation of what we call now "continental crust". This concept is applied to the Central Asian Orogenic Belt (CAOB), which is a global major accretionary orogen formed after the closure of the Paleo-Asian Ocean, and to its actualistic analogues - orogenic belts and accretionary complexes of the Western Pacific. The main focuses of the paper are the state of activities in the study of the CAOB, the theoretical basics of the new concept of contin…
Anomalous soil CO 2 degassing in relation to faults and eruptive fissures on Mount Etna (Sicily, Italy)
1998
The relationships between soil gas emissions and both tectonic and volcano-tectonic structures on Mt. Etna have been studied. The investigation consisted of soil CO2 flux measurements along traverses orthogonal to the main faults and eruptive fissures of the volcano. Anomalous levels of soil degassing were found mainly in coincidence with faults, whereas only 49% of the eruptive fissures were found to produce elevated CO2 soil fluxes. This result suggests that only zones of strain are able to channel deep gases to the surface. According to this hypothesis, several previously unknown structures are suggested. Based on our geochemical data, new structural maps of different areas of Etna are p…
El arquitecto Rafael Guastavino (1842-1908): obra en cuatro actos
2018
[EN] This text presents extensive new information on the figure of architect Rafael Guastavino Moreno (1842-1908), those around him, and his personal and family relationships with architecture. It also examines other artistic fields and trades such as music, carpentry and winemaking, all of which influenced and obtained feedback for Guastavino¿s architecture within the historical, political and economic situation of the three places where he lived in Spain: Valencia, Barcelona and Almudévar (Huesca), before emigrating to the United States of America, where his successful professional career as an architect is widely recognized in the literature
Complex vein systems as a data source in tectonics: An example from the Ugab Valley, NW Namibia
2014
Abstract Neoproterozoic metaturbidites in the Lower Ugab Domain, Namibia, contain a complex network of four sets of quartz-calcite veins, overprinted by km-scale folds associated with four regional foliations. The veins formed by fluid overpressure predating the main deformation. Deformation structures developed at the junction of two mobile belts during the assembly of Gondwana, the NS Kaoko Belt, and the EW trending Damara Belt. Km-scale NS trending folds were initiated during EW constriction in the Kaoko Belt, while their further development and all subsequent events are related to constriction in the EW-Damara Belt, with coeval sinistral strike slip in the Kaoko Belt. Deformation of the…
Sedimentology and sequence stratigraphy of wedge-top clastic successions: Insights and open questions from the upper Tortonian Terravecchia Formation…
2013
Abstract An up to 1250 m-thick clastic succession, the upper Tortonian Terravecchia Formation (TRV), has been analysed in detail in the middle–late Miocene Scillato wedge-top Basin grown above an already deformed tectonic stack in the northern Sicilian fold-and-thrust belt. The study involved field-based sedimentological and stratigraphic analyses aimed to determine to what extent both the depositional and sequence stratigraphic evolution of the Scillato Basin have been ruled by syn-sedimentary compressional to transpressional tectonics. Widespread intraformational angular unconformities associated with sudden change of palaeocurrents pattern and successive source area shifting suggest that…