Search results for "Facies"
showing 10 items of 232 documents
Facies, architecture and genetic controls of carbonate ramp aprons development
Cool-water Carbonate Ramp Aprons (CRA) are depositional systems in which skeletal sand and gravel are redistributed basinwards on a ramp, off a shallow carbonate platform by tractive currents as a result of flow funnelling in between topographic highs. These deposits are different and should not be confused with the carbonate apron models proposed by of Mullins and Cook (1986) who describe either carbonate deep water turbiditic systems accumulated at the base of the slope or talus cones formed at the margins of carbonate build ups. A key example of CRA facies assemblages is represented by the Early Pleistocene, Favignana Calcarenite where bimodal depositional processes, occurring in a water…
The Residual Shear Strength of the Shaly and Sandy Facies of the Opalinus Clay
2018
The paper presents a comprehensive laboratory campaign carried out with the aim to asses the residual strength of the Opalinus Clay. Ring shear tests with vertical effective stress up to 1 MPa were performed on remoulded samples of two different facies of the Opalinus Clay. Test results show that the «Shaly» facies is characterized by a low range of variation of residual strength while the strength of the «Sandy» facies is very sensitive to the variation of grain size distribution. Microstructural analyses (SEM) suggest that the difference in the observed mechanical behavior of the two facies can be related to different particles arrangements along the shear surfaces.
Contrasting metamorphic evolution of metasedimentary rocks from the Çine and Selimiye nappes in the Anatolide belt, western Turkey
2003
P-T conditions, mineral isograds, the relation of the latter to foliation planes and kinematic indicators are used to elucidate the tectonic nature and evolution of a shear zone in an orogen exhumed from mid- crustal depths in western Turkey. Furthermore, we discuss whether simple monometamorphic fabrics of rock units from different nappes result from one single orogeny or are related to different orogenies. Metasedimentary rocks from the Cine and Selimiye nappes at the southern rim of the Anatolide belt of western Turkey record different metamorphic evolutions. The Eocene Selimiye shear zone separates both nappes. Metasedimentary rocks from the Cine nappe underneath the Selimiye shear zone…
1999
Two retrograde, amphibolite facies shear zones were studied to explore the relationship between retrograde mineral reactions, volume strain, fluid flow, mylonitization, and coaxial versus noncoaxial deformation. The two shear zones are the contractional Mafwewu Hills shear zone and the transcurrently displacing Mkamasa River shear zone of northern Malawi. In general, shear-zone formation is characterized by the breakdown of feldspar and biotite and the formation of sillimanite, quartz, and water. Silica, alkali, and alkali earth elements were mobile. Mass-balance calculations, based on major- and trace-element geochemistry, indicate as much as 50%–60% volume loss in mylonite. Fluid to rock …
Sequence stratigraphy of a mesozoic carbonate platform-to-basin system in Western sicily
2009
Abstract Sequence stratigraphic studies of the Triassic through Paleogene carbonate successions of platform, slope and basin in western Sicily (Palermo and Termini Imerese Mountains) have identified a sedimentary cyclicity mostly caused by relative oscillations of sea level. The stratigraphic successions of the Imerese and Panormide palaeogeographic domains of the southern Tethyan continental margin were studied with physical-stratigraphy and facies analysis to reconstruct the sedimentary evolution of this platform-to-basin system. The Imerese Basin is characterized by a carbonate and siliceous-calcareous succession, 1200–1400m thick, Late Triassic to Eocene in age. The strata display a typ…
Triasina hantkeni limestones from western Sicily
2010
Systems tracts and depositional sequences in a carbonate setting: a study of continuous outcrops from platform to basin at the scale of seismic lines
1991
Abstract The application of sequence stratigraphy concepts to carbonates is feasible and this paper presents an example of its successful application. The continuity and lateral extent of outcropping sedimentary sections observed at the scale of a seismic line from platform to basin in the Southern Vercors Plateau (western Alps, France) confirm the validity of sequence stratigraphy concepts when applied to carbonate depositional systems. From the stratal patterns displayed in outcrop, we determined that carbonate lowstand systems tracts are major components in the basin, even in the deep pelagic realm. Transgressive and highstand systems tracts are very thin, a response to starvation. In co…
Anisotropic volumetric behaviour of Opalinus clay shale upon suction variation
2016
Opalinus clay shale is under consideration to serve as the host geomaterial for the underground storage of nuclear waste in Switzerland. Water retention behaviour and anisotropic behaviour represent two main features of this geomaterial; however, a comprehensive understanding of the interaction between these two features is still lacking. This paper aims to provide a detailed experimental analysis of the coupling between the water retention capacity and the anisotropic behaviour of two facies (shaly and sandy) of the Opalinus clay shale. The response of the tested geomaterials is characterised by an unequal swelling and shrinkage response in directions parallel and perpendicular to the bed…
The Role of Anisotropy on the Volumetric Behaviour of Opalinus Clay upon Suction Change
2017
An experimental investigation to analyse the anisotropic volumetric response of shaly and sandy facies of Opalinus Clay upon suction variations is presented. Obtained results demonstrate the different behaviour of the tested facies to a wetting-drying cycle. The shaly facies exhibits higher water retention capacity and stronger volumetric response than the sandy facies. Anisotropic response is experienced by both facies with the strain perpendicular to bedding higher than in the parallel direction. The sandy facies exhibits a more pronounced anisotropic behaviour in particular during the drying phase. A detailed analysis of the response in the two directions with respect to the bedding orie…