Search results for "Facies"
showing 10 items of 232 documents
Age of Palaeozoic granites and metamorphism in the Tuvino-Mongolian Massif of the Central Asian Mobile Belt: loss of a Precambrian microcontinent
2001
Abstract The Tuvino-Mongolian Massif (TMM) was previously interpreted as a Precambrian block within the Central Asian Mobile Belt. According to this idea, it consists of tectonic slices composed of metamorphic rocks of pre-Mesoproterozoic basement that experienced two episodes of regional metamorphism, and Mesoproterozoic ‘cover rocks’ that were reworked together with the basement during high-grade metamorphism. Zircon U–Pb dating of granitoids from all metamorphic complexes demonstrates that the earliest metamorphic event occurred at 536±6 Ma, significantly later than the deposition of the cover rocks. Regional upper amphibolite-facies metamorphism, which affected all metasedimentary units…
The carbonates of the Permian Lakes of North Massif central, France
1992
During the Permian, large fluvio-lacustrine basins occurred within the West European Hercynian chain. The deposits were mainly detrital (conglomerates, sandstones and pelites). The two studied sites, Couy borehole and Aumance basin contain several dolomitic beds alternating with pelites containing Ostracods. The carbonate layers constitute various dolomitized facies with dolosparite, laminated and bituminous dolomites, oolites, oncolites and stromatolites, and pedological nodules. Microfacies are varied. The dolomite crystals can be either isolated rhombs scattered in pelites or rhombs and xenomorphic crystals cementing sandstones; in dolomicrites, dolomicrosparites and dolosparites, crysta…
Rift-controlled fluvial/tidal transitional series in the Oukai¨meden Sandstones, High Atlas of Marrakesh (Morocco)
1996
Abstract The Carnian formation of the Oukai¨meden Sandstones was deposited in the northwestern corner of the African craton along tectonic troughs grouped as a WSW-ENE rift system on the southwestern margin of the Tethys. Red sandstones represent mainly distal braided-stream deposits where very extensive sand flats with 3D dunes, 2D sand waves and high-regime horizontally laminated sandstones predominate. The similarities in orientation between current patterns and trough border faulting, the sudden large variations in the thickness of deposits and the occurrence of lateral alluvial fans along the marginal faults are all evidence of the tectonic control of sedimentation. The middle part of …
Using high-resolution stratigraphy and structural analysis to constrain a “polyphase” tectonics in wedge-top basins. Inferences from the Late Tortoni…
2012
Abstract The present paper aims to show, both from a stratigraphic and structural points of view, the main features of a wedge-top syntectonic basin which evolved recording polyphase and non-coaxial tectonics. The study area is the Scillato Basin ( SB ), a roughly N–S-oriented structural depression located in the central-northern sector of the Sicililian Maghrebides. There, an approximately 1300 m-thick upper Serravallian to upper Tortonian succession of clastic units outcrops as a portion of the Neogene syntectonic covers of the Sicilian fold and thrust belt. Within the outcropping succession the upper Tortonian Terravecchia Fm represents the main topic of this paper. A multidisciplinary a…
Metamorphism of Precambrian–Palaeozoic schists of the Menderes core series and contact relationships with Proterozoic orthogneisses of the western Çi…
2006
The tectonic setting of the southern Menderes Massif, part of the western Anatolide belt in western Turkey, is characterized by the exhumation of deeper crustal levels onto the upper crust during the Eocene. The lowermost tectonic units of the Menderes Massif are exposed in the Çine Massif, where Proterozoic basement orthogneisses of the Çine nappe are in tectonic contact with Palaeozoic metasedimentary rocks of the Selimiye nappe. In the southern Çine Massif, orthogneiss and metasedimentary rocks are separated by the southerly dipping Selimiye shear zone, preserving top-to-the-S shearing under greenschist facies conditions. In contrast, in the western Çine Massif, the orthogneiss is deform…
Late Archaean foreland basin deposits, Belingwe greenstone belt, Zimbabwe
2001
Abstract The c. 2.65 Ga old sedimentary Cheshire Formation of the Belingwe greenstone belt (BDB), central Zimbabwe, has been studied in detail for the first time to shed some light on the much debated evolution of this classical belt. The Cheshire Formation rests sharply on a mafic volcanic unit (Zeederbergs Formation) and comprises a basal, eastward-sloping carbonate ramp sequence built of shallowing-upward, metre-scale sedimentary cycles. The cycles strongly resemble Proterozoic and Phanerozoic carbonate cycles and might have formed by small-scale eustatic sea level changes. The top of the carbonate ramp is represented by a karst surface. The carbonates are overlain by and grade laterally…
A possible tsunami deposit around the Jurassic–Cretaceous boundary in the Boulonnais area (northern France)
2005
Abstract An unusual succession of facies locally deposited around the Jurassic–Cretaceous boundary in the Boulonnais (northern France) is attributed to a tsunami event by comparison with recent tsunami deposits. This sedimentary succession includes basal erosion with reworked lithified blocks, soft-sediment deformations, an erosional conglomerate overlain by wood fragments and clays containing continental and marine fossils in one setting and conglomerate with mixed fauna in an other setting. The tsunami probably affected the coast of the Boulonnais area of the London–Brabant Massif. The origin of the event is unknown. It was most probably triggered by an earthquake, but other origins such …
Mesozoic tectono-sedimentary evolution of Rocca Busambra in western Sicily
2008
The Rocca Busambra ridge in western Sicily is a shallow to pelagic Meso-Cenozoic carbonate structural unit of the Sicilian fold and thrust belt with a variety of tectono-sedimentary features. Palaeofaults, unconformities (buttress unconformity, onlap, downlap), a network of neptunian dykes with several infilling generations, several large hiatuses, different facies and lateral facies changes, and erosional submarine and subaerial surfaces are observed. Detailed fieldwork and structural analyses have indicated the occurrence of fault planes with different orientations. These data, combined with facies studies and physical-stratigraphy analyses, allow for the distinction of different depositi…
Ground instability in the old town of Agrigento (Italy) depicted by on-site investigations and Persistent Scatterers data
2012
We combine on-site investigations with the interpretation of satellite Persistent Scatterers (PS) to analyse ground instability in the historic town of Agrigento, Italy. Geological and geomorphologic surveys, together with geostructural and kinematic analyses, depict the deformational patterns of the northwestern sector of the town, previously documented by extensive literature available for the neighbouring Valley of the Temples. The geological and geomorphologic maps are reconstructed by combining bibliographic studies, field surveys and aerial stereo-interpretation. ERS-1/2 PS data reveal deformation velocities up to 18–20 mm yr<sup>−1</sup> in 1992–2000 over the Addolorata l…
Sedimentation and tropical vegetation changes in Southern Benin (West Africa), carbon-13 tracing of organic matter dynamics and fluctuations of the s…
2007
12 pages; International audience