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1.
In the western Ahaggar shield, the transition between the Precambrian and the Ordovician units is characterised by thick volcano-sedimentary series (‘Série pourprée’ of the Ahnet). This series, in part of Cambrian age, results from the demolition of the Panafrican belt. Similar series were known in grabens located between the West African craton and the Ahaggar, from the ‘Adrar des Iforas’, in the south, to the Ougarta belt, in the north. We describe in this study a new formation identical to the ‘Série pourprée’ of the Ahnet, but cropping out in the far Southeast of the Ahaggar (In Guezzam). This new datum improves the Panafrican belt configuration. To cite this article: H. Djellit et al., C. R. Geoscience 334 (2002) 789–794. 相似文献
2.
New data about the ‘Sables fauves’ clearly show two different kinds of organisations: stratigraphic superposition of Langhian and Serravallian units to the south and embankment of Serravallian sediments in Langhian deposits to the north. The result consists in two different palaeogeographic schemes. The Langhian Sea is widely extended, forming the ‘Lectoure Gulf’, whereas the Serravallian Sea is much more reduced, with valleys fillings to the north and a little gulf to the south. This involves a tectonic activity along a structure which orientation is N120°E (‘flexure de la Douze’) and a relative rising of the northern part, of about 30 m. To cite this article: P. Gardère et al., C. R. Geoscience 334 (2002) 987–994. 相似文献
3.
Alessandro Ellero Leonardo Leoni Michele Marroni Ionel Nicolae Luca Pandolfi Franco Sartori 《Comptes Rendus Geoscience》2002,334(5):347-354
The Fenes Nappe belongs to the stack of tectonic units cropping out in the southern Apuseni Mts (Romania). It is characterised by a structural history consisting of two folding phases that developed during the time spanning from Early Aptian to Late Maastrichtian. The D1 phase produced west-northwest-verging, isoclinal to very tight folds, associated to a slaty cleavage. The main metamorphic imprint of the Fenes Nappe is linked to this deformation phase; illite and chlorite ‘crystallinity’ values indicate metamorphic conditions of the late diagenesis, close to the diagenetic zone/anchizone boundary. The subsequent D2 phase produced north-northwest-verging, parallel folds, not associated with synkinematic recrystallisation. These phases are interpreted as developed during a structural path, which includes burial at a depth of 8–10 km, followed by exhumation at shallower structural levels. To cite this article: A. Ellero et al., C. R. Geoscience 334 (2002) 347–354. 相似文献
4.
The ‘Calcaires à Productus’ of the Montagne Noire are microbial build-ups. Two formations are defined and dated respectively as Uppermost Visean (Upper Warnantian–Brigantian) and Serpukhovian on the basis on corals. That makes these limestones out to be younger than previously stated (Lower and base of Upper Warnantian–Asbian and base of Brigantian) and indicates that the development of the olistoliths and thrusts including them, due to the Variscan orogeny, was at least as young as the Upper Serpukhovian. The Serpukhovian limestones of the Montagne Noire are correlated with the Lanet Limestone (Mouthoumet Massif, Corbières) and Ardengost Limestone (central Pyrenees). To cite this article: É. Poty et al., C. R. Geoscience 334 (2002) 843–848. 相似文献
5.
Maurice Aubert 《Comptes Rendus Geoscience》2004,336(10):869-875
Preliminary soil-temperature measurements over 16 months indicate an important geothermal flux of at least 0.4 W m?2 on the summit of a scoria cone in the Cha??ne des Puys (France). This anomaly can be explained by a residual hydrothermal flux that has begun when the maar and the overlying cone were formed around 30 000 years ago. To cite this article: M. Aubert, C. R. Geoscience 336 (2004). 相似文献
6.
Muriel Rocher Marc Cushing Francis Lemeille Stéphane Baize 《Comptes Rendus Geoscience》2004,336(13):1209-1218
The ‘Île Crémieu’, a plateau of Jurassic limestones located in the southern border of the Bresse and at the Jura front, is generally considered as non-deformed. Quaternary ice sheets and drainage have underlined and cleaned out some fracture planes trending NNE and NW–SE that border and crosscut the ‘Île Crémieu’. The analysis of seismic profiles reveals NNE-trending normal faults and NW–SE-trending strike-slip faults, crosscutting the basement to Late Miocene layers. Microtectonic fieldwork shows that these faults exist and were activated during the main Cainozoic tectonic events. To cite this article: M. Rocher et al., C. R. Geoscience 336 (2004). 相似文献
7.
Annie Souriau Matthieu Sylvander Valérie Maupin Jean-François Fels Alexis Rigo 《Comptes Rendus Geoscience》2002,334(3):155-161
This study presents a detailed analysis of the seismic records of a strong explosion that occurred on 21 September 2001 at a chemical complex located south of Toulouse, France, and provoked important damages. The explosion, which is equivalent to a 3.4 magnitude earthquake, has been recorded at most of the stations of the National Seismological Network, as well as at a station under test at the ‘Observatoire Midi-Pyrénées’, 4.2 km away from the epicentre. The main seismic phases are interpreted using the known crustal structures, and a modelling with synthetic seismograms is performed. To cite this article: A. Souriau et al., C. R. Geoscience 334 (2002) 155–161. 相似文献
8.
Jean-Philippe Bellot 《Comptes Rendus Geoscience》2004,336(1):67-74
A new geological map of the Palaeozoic units from the Porquerolles Island provides evidence for two main units joined along a north–south-trending shear zone: a western unit of schist, sandstone and microconglomerates, an eastern unit of schist including calcareous rocks, metabasite and various types of mineralisations. The shear zone has experienced a main strike-slip, sinistral movement in a ductile regime, and a late westward normal movement from ductile to brittle regimes. It crosscuts an early thrust fault, marked by penetrative syn-metamorphic deformation and the abundance of quartz rods. According to geometrical relationships, the regional conic fold is interpreted as a large-scale dragging of foliation related to strike-slip faulting. Combined folding and wrenching point out a main transpressional tectonics related to the continental collision dated Middle Visean in the central and eastern parts of the Variscan Maures massif. To cite this article: J.-P. Bellot, C. R. Geoscience 336 (2004). 相似文献
9.
Guillaume Martelet Nicole Debéglia Catherine Truffert 《Comptes Rendus Geoscience》2002,334(7):449-454
For regional and national study purposes, there is a high need for updating the terrain corrections (TC) in the French gravity database. We have recomputed the TC for all the French gravity stations from 50 m out to a distance of 167 km. We compute the TC with a flat-top-prism algorithm and three DEM with grid spacing of 50, 250 and 1000 m, used in the zones 53 m/3 km, 3 km/10 km et 10 km/167 km, respectively. Analysing the DEM/station Δz and comparing our results to the ones previously obtained in the Alps area, we estimate the accuracy of our TC to be better than 1 mGal. To cite this article: G. Martelet et al., C. R. Geoscience 334 (2002) 449–454. 相似文献
10.
Anne Socquet Bruno Goffé Manuel Pubellier Claude Rangin 《Comptes Rendus Geoscience》2002,334(8):573-580
Metamorphic study on Triassic schists in the internal zone of the Indo-Burma range, essentially based on chlorite–mica equilibrium in metapelites, allows a P–T path to be quantified. During the prograde metamorphism, the geothermic gradient evolves from that of a ‘normal’ crust (30 °C km?1) to that of a thickened crust (18 °C km?1). The peak conditions are around 8 kbar and 450 °C. This thickening (25–30 km) is probably made in a wedge set up between the Late Cretaceous and the Eocene, in front of the obduction. The obtained cold retrograde path requires a mechanism allowing thermal re-equilibration, implying slow exhumation. It occurred along a shear zone that put into contact the micaschists of the core with the Triassic schists of the roof. To cite this article: A. Socquet et al., C. R. Geoscience 334 (2002) 573–580. 相似文献