Search results for "Tectonic"
showing 10 items of 470 documents
A complex thrust sequence in western Himalaya: the active Medlicott Wadia Thrust.
2017
15 pages; International audience; The recent activity of the Medlicott-Wadia Thrust (MWT) is investigated by geomorphic and tectonic studies in the Riasi zone, south of the Pir Panjal range (India, Jammu-Kasmir state of western Himalaya). In the Riasi area, the MWT forms a splay of five faults that dip northward. The recent activity of the splay is quantified using a set of deformed Quaternary alluvial units. The central branch of the thrust splay moved Precambrian limestones above Quaternary sediments and is sealed by 36 ± 3 ka (youngest OSL age) deposits. The other branches offset the top of a 15 ± 1 ka (youngest OSL age) alluvial fan by 180 to 120 m; the two southernmost branches form 17…
Permian-Triassic Rifting Stage
2019
International audience; The Permian-Triassic rifting represents the first of the two Mesozoic rifting stages recorded in the Iberian Peninsula. Its first phases of development started during the Early Permian, and were linked to the beginning of the break-up of Pangea, the large, unique and rheologically unstable supercontinent that mainly resulted from the collision of Gondwana and Laurussia. This chapter analyzes this first rifting stage in Iberia in two separate phases, an initial or tectonic phase, and a later mature phase. This analysis focuses on the main Permian-Triassic basins of the Iberian Peninsula: the Pyrenean, Iberian, Catalan, Ebro and Betic basins, as well as the basins loca…
Calculating the long-term displacement rates of a normal fault from the high-resolution stratigraphic record (early Tethyan rifting, French Alps)
2003
Displacement rates of normal faults deduced from stratigraphic data are often unreliable. Here we calculate the velocity of motion on a normal fault from the variations in accommodation potential on both sides of the fault within a highresolution time-frame established by biostratigraphy and physical stratigraphy. Our example is the Ornon normal fault bounding the Early Jurassic Bourg-d’Oisans Basin formed during Tethyan rifting. We show that motion on the fault was discontinuous when examined at high resolution and over a long time interval. During a first interval (Hettangian to Sinemurian Arietites bucklandi zone) a low rate of displacement (= 202–423 m Myr -1 ) coeval with diffused exte…
Synthèse préliminaire des travaux menés sur le bassin de Benguela (Sud Angola) : implications sédimentologiques, paléontologiques et structurales.
2006
12 pages; International audience; Les travaux menés dans le bassin de Benguela ont apporté une moisson de nouvelles données de terrain quant à la période apto-albienne de ce secteur ouest africain. Outre les résultats majeurs obtenus en ce qui concerne les faunes d'ammonites jusqu'alors peu étudiées dans ce bassin, et qui ont permis des corrélations indispensables pour la compréhension du fonctionnement de la sédimentation, cette étude a permis de mettre en évidence une compartimentation remarquable de la sédimentation et des structures de tectonique salifère. Des tels résultats ont une portée à la fois fondamentale et appliquée. En effet, il paraît que le bassin de Benguela soit un des rar…
The role of slabs and oceanic plate geometry in the net rotation of the lithosphere, trench motions, and slab return flow
2012
International audience; [1] Absolute plate motion models with respect to a deep mantle reference frame (e.g., hot spots) typically contain some net rotation (NR) of the lithosphere. Global mantle flow models for the present-day plate setting reproduce similarly oriented NRs but with amplitudes significantly smaller than those found in some high NR Pacific hot spot reference frames. It is therefore important to understand the mechanisms of NR excitation, which we attempt here with two-dimensional cylindrical models of an idealized Pacific domain. We study the influence of slab properties, oceanic ridge position, continental keels, and a weak asthenospheric layer on NR and trench migration. F…
Tectonics and seismicity of the Tindari Fault System, southern Italy: Crustal deformations at the transition between ongoing contractional and extens…
2006
The Tindari Fault System (southern Tyrrhenian Sea, Italy) is a regional zone of brittle deformation located at the transition between ongoing contractional and extensional crustal compartments and lying above the western edge of a narrow subducting slab. Onshore structural data, an offshore seismic reflection profile, and earthquake data are analyzed to constrain the present geometry of the Tindari Fault System and its tectonic evolution since Neogene, including the present seismicity. Results show that this zone of deformation consists of a broad NNW trending system of faults including sets of right-lateral, left-lateral, and extensional faults as well as early strike-slip faults reworked …
L'anfiteatro di Sabratha: vecchie indagini e nuove ricerche
2012
L’Anfiteatro di Sabratha, ignorato dai viaggiatori del XVIII e XIX secolo, venne segnalato nel 1912 da Henri Méhier de Mathuisieulx ed indagato da Renato Bartoccini a partire dal 1924. Gli scavi e le ricerche portate avanti in quegli anni permisero di rimettere in luce gran parte del monumento, che rimase tuttavia non pubblicato. Recenti scavi e ricerche hanno adesso permesso di redigere un nuovo rilievo ed un nuovo studio del monumento. Il grande edificio, realizzato in conci di calcarenite locale, venne costruito sfruttando una cava di pietra alla periferia orientale della città antica probabilmente alla metà circa del II secolo d.C. e, contrariamente a quanto finora ritenuto, venne effet…
A Low Cost Customizable Micro-ROV for Environmental Research - Applications, Advances and Challenges
2016
Summary Several shallow submarines areas are characterized by considerable releases of hydrocarbon gases, which, during earthquakes or volcanic activity, may suddenly and violently occur. In some instances, changes in chemical and physical properties of gas emissions, which are generated by geothermal systems connected to the volcanoes’ plumbing system, are important precursors of volcanic activity and useful indices for the study of the geothermal field. Furthermore, some superficial structures such faults, landslide slopes or archaeological relics should be studied with such a high detail that geophysical and bathymetric surveys are unable to provide. In response to the needs increasingly…
Coseismic extension recorded within the damage zone of the Vado di Ferruccio Thrust Fault, Central Apennines, Italy
2018
Recent high resolution hypocentral localisation along active fault systems in the Central Apennines illuminates the activation of seismogenic volumes dipping at low angle (<30°) in extensional settings overprinting contractional deformations affecting the continental crust of the Adria microplate. Individuation of the geological structures and of the fault processes associated with these seismic patterns will contribute to the interpretation of seismic sequence evolution, and seismic hazard studies.Here we report field and microstructural evidence of seismogenic extensional faults localized within pre-existing thrust fault zones. The Vado di Ferruccio Thrust Fault (VFTF) is a narrow …
Late Quaternary high uplift rates in northeastern Sicily: evidence from calcareous nannofossils and benthic and planktonic foraminifera
2011
The northeastern part of Sicily is characterized by intense seismic activity. Several systems of faults have been recognized in Pliocene and Pleistocene sediments in the area and, in fact, estimates of uplift rates are among the highest recorded in Sicily and south Italy. We examined calcareous nannofossil and benthic and planktonic foraminifera assemblages from pelitic sediments of the Contrada Zura section (Barcellona Pozzo di Gotto Basin, Furnari village, Messina). The occurrence of Emiliania huxleyi, a coccolithophore species which appeared in the oceanic record about 270,000 years ago, is witness to the uniqueness of this outcrop, while the planktonic/benthic foraminifera ratio indicat…