Search results for "Tectonic"
showing 10 items of 470 documents
Effect of the relative optical air mass and the clearness index on solar erythemal UV irradiance
2014
This paper analyses the effects of the clearness index (Kt) and the relative optical air mass (mr) on erythemal UV irradiance (UVER). The UVER measurements were made in Valencia (Spain) from 6:00 am to 6:00 pm between June 2003 and December 2012 and (140,000 data points). Firstly, two models were used to calculate values for the erythemal ultraviolet irradiance clearness index (KtUVER) as a function of the global irradiance clearness index (Kt). Secondly, a potential regression model to measure the KtUVER as a function of the relative optical air mass was studied. The coefficients of this regression were evaluated for clear and cloudy days, as well as for days with high and low ozone levels…
Seguimiento del trabajo no presencial: retroalimentación y optimización
2015
[EN] Within the context of UPV’s project for improving the learning process through innovation, the TASCA group has developed and applied different strategies to assess student’s out-of-class work. This work has allowed us to collect feedback from proposed out-of-class activities, like whether the deadlines for assignments have been under or overestimated, or students’ opinion, to improve thos activities. We have test the usefulness of these strategies in nine different degrees. In general, there is a great variability in the time students devote to a given task and, in some cases, no positive correlation is observed between that time and the obtained results. Hence, by performing this kind…
A tectonic inversion by steps during the Cenozoic : the Dover Strait
2004
Abstract The Boulonnais is a dome incised by a former marine gulf inset into a zone of tectonic inversion from the Middle Eocene, which was already partly excavated at least at the Upper Eocene. New sedimentological and paleopedological data obtained within the Boulonnais, completed with old seismic profiles, allow a better understanding of the inversion process which developed step by step. The initial breaching probably took place in the late Eocene. The Dover Strait was probably opened during the Lutetian, a part of the Oligocene and the late Neogene. Oligocene and Pliocene faunal assemblages are identical on both sides of the Strait. It was closed again for tectonic and eustatic reasons…
Large deep-seated slump structure off Ischia volcanic island, Eastern Tyrrhenian sea (Italy)
2012
Ischia island is located over the Campania sector of Eastern Tyrrhenian margin and represents the sub-aerial section of a larger, E-W trending volcanic ridge including others submerged or buried volcanic edifices. The island itself result from the coalescence of a multitude of small to medium scale eruptions leading to the emplacement of domes, lava flow and pyroclastic deposits and ignimbrites (VEZZOLI et al., 1988) ranging from alkali basalts to trachytes. The oldest basement dates back to 150 ky and crops out along the perimeter of the island especially to the south. Latest eruption occurred in 1302 A.D. and together with strong hydrothermal activity, ground uplift and seismic shaking in…
Extremely fast Holocene coastal landscape evolution in the Kachchh Upland (NW India): Clues from a multidisciplinary review
2023
The coastal landscape of the Kachchh Upland (KU) region (NW-India) changed over the last few thousand years from a shallow marine gulf to a salty desert (1-4 meters asl). In this area, bordered to the south by the Northern Hill Range (NHR), the tectonic-climatic interaction triggered the sea level fall from +2/4 m circa (6000-2000 BP) to zero. An ancient river pattern deposited a tidally regulated delta area during the sea level fall that stopped 2000-3000 years ago due to tectonic activity and a dry climate. Deltaic-alluvial fans (DAF) in front of the NHR suggest that the KU's tectonic activity led to fast landscape evolution. We explored such drastic changes by integrating scientific info…
A genetic link between synsedimentary tectonics-expelled fluids, microbial sulfate reduction and cone-in-cone structures
2018
14 pages; International audience; The late Jurassic (Tithonian) marlstones of the Boulonnais area (English Channel, France) contains diagenetic carbonate beds and nodules. Some nodules exhibit cone-in-cone structures on their lower face. We studied such nodules using various techniques of imaging and chemical (major and trace-elements) and isotopic analyses (Ccarb, Corg, O and S stable isotopes). We interpret the cone-in-cone to be the end product of carbonate-nodule formation during early diagenesis. The diagenetic carbonate precipitation was induced by microbial activity (bacteria and(?) archeae) fueled by upward-migrating fluids. Fluid expulsion was itself triggered by synsedimentary fau…
Short-term occupations at high elevation during the Middle Paleolithic at Kalavan 2 (Republic of Armenia).
2021
The Armenian highlands encompasses rugged and environmentally diverse landscapes and is characterized by a mosaic of distinct ecological niches and large temperature gradients. Strong seasonal fluctuations in resource availability along topographic gradients likely prompted Pleistocene hominin groups to adapt by adjusting their mobility strategies. However, the role that elevated landscapes played in hunter-gatherer settlement systems during the Late Pleistocene (Middle Palaeolithic [MP]) remains poorly understood. At 1640 m above sea level, the MP site of Kalavan 2 (Armenia) is ideally positioned for testing hypotheses involving elevation-dependent seasonal mobility and subsistence strateg…
Modelo de cabalgamiento profundo para el Alto Atlas (Marruecos). Implicaciones sísmicas en la zona de colisión entre Eurasia y Africa
2007
Previous crustal models of the High Atlas suppose the existence of a mid-crustal detachment where all the surface thrusts merged and below which the lower crust was continuous. However, both seismic refraction data and gravity modeling detected a jump in crustal thickness between the High Atlas and the northern plains. Here we show that this rapid and vertical jump in the depth of Moho discontinuity suggests that a thrust fault may penetrate the lower crust and offset the Moho (deep-rooted “thick skinned” model). The distribution of Neogene and Quaternary volcanisms along and at the northern part of the High Atlas lineament can be related to the beginning of a partial continental subduction…
Geochemical characteristics of Cretaceous carbonatites from Angola
1999
Abstract The Early Cretaceous (138–130 Ma) carbonatites and associated alkaline rocks of Angola belong to the Parana-Angola-Etendeka Province and occur as ring complexes and other central-type intrusions along northeast trending tectonic lineaments, parallel to the trend of coeval Namibian alkaline complexes. Most of the Angolan carbonatite-alkaline bodies are located along the apical part of the Mocamedes Arch, a structure representing the African counterpart of the Ponta Grossa Arch in southern Brazil, where several alkaline-carbonatite complexes were also emplaced in the Early Cretaceous. Geochemical and isotopic (C, 0, Sr and Nd) characteristics determined for five carbonatitic occurren…
The Mulgandinnah Shear Zone; an Archean crustal scale strike-slip zone, eastern Pilbara, Western Australia
1998
Abstract A large part of the deformation in the Archean Pilbara granitoid-greenstone terrain is localized in relatively narrow shear zones. The Mulgandinnah shear zone (MSZ) is a major one of these, with a width up to 8 km, that can be followed for over 70 km along strike in the Shaw Batholith in the eastern Pilbara. It forms part of the Mulgandinnah Lineament, that can be traced to the Lalla Rookh Basin and the Carlindi Batholith in the north, giving it a total length of over 150 km. The MSZ contains both mylonites and ultramylonites, both of which have foliations that are subvertical to steeply dipping, with the ultramylonitic foliation overprinting the mylonitic foliation to form more lo…