Search results for "Tectonic"
showing 10 items of 470 documents
Evidence from zircon dating for existence of approximately 2.1 Ga old crystalline basement in southern Bohemia, Czech Republic
1993
Zircon ages are reported for three Moldanubian amphibolite grade orthogneisses from the southern Bohemian Massif obtained by conventional U/Pb analyses. For two of these orthogneisses, conventional U/Pb data are supported by ion microprobe single zircon ages or single grain evaporation data. The amphibolite grade orthogneisses, occurring in three small tectonic lenses within the Varied Group close to the South Bohemian Main Thrust, are of tonalitic, granodioritic or quartz dioritic composition.
3D Numerical Modelling of Salt Tectonics
2017
Summary Many factors have been suggested to affect the development of salt structures, including sedimentation, brittle sediment deformation, multiple tectonic events and basement topography. To unravel the relative importance of these processes, we performed high resolution 2D and 3D thermo-mechanical simulations that take these factors into account, while incorporating nonlinear salt creep laws and visco-elasto-plastic rock properties. Simulations show that the sedimentation rate affects both the speed with which structures form, and the spacing between the salt structures, which is larger for higher rates. Consistent with earlier sandbox experiments, we find that there is a feedback betw…
Geophysical investigation of Pleistocene volcanism and tectonics offshore Capo Vaticano (Calabria, southeastern Tyrrhenian Sea)
2015
Abstract Magma upwelling forming volcanic plumbing systems in back arc settings is typically controlled by extensional tectonic structures of the upper crust. Here we investigate this process in the area between the volcanic arc of the Aeolian Islands and the Calabrian arc (SE Tyrrhenian Sea) by integrating morpho-bathymetry and reflection seismic data with the outcomes of “Inverse 3D magnetic modeling” of previously gathered aeromagnetic data. Morpho-bathymetric data highlight the presence of a seamount ∼10 km offshore Capo Vaticano Promontory (eastern Calabria). This feature, named Capo Vaticano seamount is composed of a series of NE-trending ridges, the greatest of which (R1) is ∼12 km l…
Soil CO2 degassing along tectonic structures of Mount Etna (Sicily): the Pernicana fault
1997
Abstract Carbon dioxide emissions from the soil have been investigated along lines of equally spaced sampling points perpendicular to the Pernicana fault on Mt Etna. Anomalous values of soil CO2 have been found not only along the fault plane, but also along directions parallel to it, both to the N and to the S of the main fault. The acquired data seem to reveal a shallow step-like geometry of the Pernicana fault system with parallel faults being generally not deeper than the interface between Etna's volcanic cover and its sedimentary basement (a few hundred meters). The distribution of the anomalous CO2 emissions has also revealed that the Pernicana fault continues at least as far as the Io…
Fluid-pressure controlled soft-bed deformation sequence beneath the surging Breiðamerkurjökull (Iceland, Little Ice Age).
2009
16 pages; International audience; The general subject of this paper is subglacial deformation beneath Breiðamerkurjökull, a surging Icelandic glacier. More specifically it discusses the evolution and the role of fluid pressure on the behaviour of subglacial sediments during deformation. During Little Ice Age maximum, the two outcrops studied, North Jökulsarlon (N-Jk) and Brennhola-Alda (BA), were located at 2550 m and 550 m respectively from the front of the Breiðamerkurjökull. Sedimentological analysis at the forefield of the glacier shows thick, coarse glaciofluvial deposits interbedded with thin, fine-grained shallow lacustrine/swamp deposits, overlain by a deformed till unit at N-Jk. BA…
Thermal anomalies in fumaroles at Vulcano island (Italy) and their relationship with seismic activity
2013
Abstract Fumarole thermal monitoring is a useful tool in the evaluation of volcanic activity, since temperatures strongly relate to the upward flux of magmatic volatiles. Once depurated from meteorological noise, their variations can reflect permeability changes due to crustal stress dynamics eventually associated to seismic activity. In this work, we discuss a fumarole temperature record acquired in the period September 2009–May 2012 at Vulcano island (Italy), during which changes of volcanic state, local seismic activity and teleseisms occurred. Apart from positive thermal anomalies driven by increments in volcanic activity, we observed 3 episodes at least of concurrence between tectonic …
Geological Map of the Rocca Busambra-Corleone region (western Sicily, Italy): explanatory notes
2011
The geology of the Rocca Busambra-Corleone region, in centralwestern Sicily, is relevant to the understanding of the central sector of the Maghrebian-Sicilian fold-and-thrust belt. In the investigated area Mesozoic shallow- and deep-water carbo - nate deposits pertaining respectively to the Trapanese and the Sica - nian successions, and a thick Oligo-Miocene numidian flysch body, crop out. Minor outcrops of Cretaceous-Palaeogene Sicilide complex and syn-orogenic deposits of the Late Serravallian-Early Messinian Castellana Sicula and Terravecchia formations are also present. A structural analysis reveals complex tectonic relationships between the Trapanese carbonate platform tectonic unit (t…
Deep controls on foreland basin system evolution along the Sicilian fold and thrust belt
2015
Abstract Neogene-Quaternary wedge-top-basins arose during the Sicilian fold and thrust belt (FTB) build-up. The infilling sedimentary successions are: i) middle-upper Miocene silicoclastics succession, accommodated on top of the accreted Sicilide and Numidian flysch nappes; ii) upper Miocene-lower Pliocene deepening-upwards sediments unconformably overlying the inner Meso-Cenozoic deep-water, Imerese and Sicanian thrust units; iii) Upper Pliocene-Quaternary coastal-open shelf deposits unconformably covering (in the outer sector of the FTB) a tectonic stack (Gela thrust system). These successions are characterized by a basal unconformity on the deformed substrate believed to be the depositio…
Devonian to Permian plate tectonic cycle of the Paleo-Tethys Orogen in southwest China (I): Geochemistry of ophiolites, arc/back-arc assemblages and …
2009
Abstract The Paleo-Tethys Orogen in southwest China is an amalgamation of continental terranes (Sibumasu, Simao and Yangtze), which are bounded by ophiolite belts (Ailaoshan, Jinshajiang and Changning–Menglian) that represent former ocean basins. This study concentrates on ophiolites, arc/back-arc assemblages, and within-plate igneous rocks that occur in this complex orogen. Mainly based on geochemical fingerprinting of basalts, the Paleo-Tethys ophiolites are here classified as MORB and SSZ types. The Ailaoshan ophiolite (NMORB-type; ca. 387–374 Ma) is associated with a non-volcanic segment of the rifted western Yangtze margin. The Jinshajiang ophiolite (EMORB-type; 346–341 Ma), which has …
Age and Origin of Paleogene Granitoids from Western Yunnan Province, China: Geochemistry, SHRIMP Zircon Ages, and Hf-in-Zircon Isotopic Compositions
2015
We report geochemical data, SHRIMP zircon ages and Hf-in-zircon isotopic compositions for Cenozoic granitoids from major fault systems in the Tethyan belt in western Yunnan Province, southwestern China. Four magmatic pulses occurred in the Paleogene, namely at ca. 57 Ma, ca. 50 Ma, 45–40 Ma, and 38–34 Ma. Early magmatism of this episode (57–50 Ma) produced S-type granites whose zircons yielded eHf(t) values of −5.0 to −0.3. In contrast, late magmatism of this episode reflects heterogeneous sources. Zircons from a granite porphyry along the Ailaoshan-Red River fault system have slightly positive eHf(t) values suggesting derivation from relatively young crust and/or a juvenile source. However…