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1.
A basalt outcrop was discovered on Alderdice Bank on the outer Louisiana continental shelf. The basalt shows an age of 76.8 ± 3.3 × 106 years. Textural, mineralogical, and chemical characteristics indicate that it is an alkali basalt of shallow intrusive origin. It was probably brought to the seafloor by salt tectonics and exposed due to salt dissolution.An accurate account of the Mesozoic geologic history of the Gulf of Mexico must consider the apparent consanguinity of all magmatic rocks of the region, including the Alderdice Bank basalt, and the apparent basinward decrease in age of magmatic activities. 相似文献
2.
The Hassi R’Mel field, which is the largest gas field in Algeria, produces principally gas condensate. The produced gas and oil comes from four reservoirs of Triassic age (reservoir A, reservoir B, reservoir C, and the Lower Series). All the previous studies in this field focused only on the upper reservoirs (A, B, and C), which have shown an excellent petrophysical properties. However, due to the presence of shale facies as well as volcanic intrusions, the Lower Series reservoir has been less explored. Thus, our study is mainly focused on this Lower Series in order to find the best sandy levels. The aim of this paper was to determine the facies types in the area, their distribution in the southern area of the Hassi R’Mel gas field, and their depositional environment. The Triassic rocks in this field are divided into four formations. From the youngest to oldest, these are S4, Lower Shale, Horizon A, and the Lower Series. The Lower Series formation can be further divided into three members (shaly sandstone, andesite, and lower shale). The shaly sandstone member within the Lower Series is composed of four units that are present all over the study area with an important pinch-out toward the northern part. The depositional environment within the defined units is a braided fluvial system in the southern part that evolves into a meandering fluvial system toward the north. Thus, the study area is considered to be a transitional zone between two depositional systems. 相似文献
3.
Résumé L'objectif de ce travail est de fournir aux hydrologues travaillant sur l'Algérie du Nord un modèle numérique de terrain (MNT) permettant la mise en ?uvre de méthodes d'estimation régionales de paramètres hydrologiques tels que les débits de crue instantanés décennaux ou les apports moyens annuels. Il doit permettre une détermination satisfaisante des contours des bassins versants et l'obtention de paramètres morphométriques comparables entre eux sur l'ensemble de la zone d'étude. Le MNT que nous proposons est un compromis entre des tailles de pixels petites donnant une bonne précision et des pixels plus grands permettant de couvrir uniformément la zone. Nous montrons que le MNT à la maille de 100 m est parfaitement adapté sous réserve de l'avoir préalablement corrigé manuellement dans les zones endoréiques et dans les zones relativement planes. Ce MNT permet de retrouver correctement les principaux paramètres morphométriques utilisés en hydrologie. Nous mettons donc à la disposition des hydrologues ce MNT à 100 m dans une projection Lambert bien adaptée aux besoins de l'hydrologie algérienne. Editeur Z.W. Kundzewicz Citation Rezak, S., Laborde, J.-P., et Errih, M., 2012. Validation d'un modèle numérique de terrain adapté à la modélisation hydrologique régionale sur l'Algérie du Nord. Hydrological Sciences Journal, 57 (5), 928–941. 相似文献
4.
An increasing volume of evidence suggests that normal faulting and graben formation associated with salt diapirism may be
catastrophic. The evidence includes: 1) removal of solid salt from the diapirs by dissolution, 2) the nature of rock outcrops
at the crests of domes, 3) seismic profiles showing recent displacement of the seafloor, and 4) changes in coral growth rates
at the East Flower Garden Bank. The possibility of catastrophic movement of the seabed is an engineering constraint that must
be addressed prior to emplacing structures such as jack-up rigs and production platforms. 相似文献
5.
Bentonitic clay deposit of M’zila locates in the North border of the upstream portion of the Chélif basin “Bas Chélif” down to 35 km NE of Mostaganem. It consists of 14 layers (most recent) 1 to 14 (oldest) forming the North and South flanks of an E–W Syncline. These layers are enclosed in the median blue marls formation of the Upper Miocene of the “Bas Chélif” basin lying unconformably on the ante thrust sheet sandstone formation. This median member contains metric cinerites thick continuous levels and could beings originally bentonitic clay region of M’zila. The cinerites are the product of explosive type in the volcanic eruption, usually deposited in the marine environment. They are formed by a more or less rich feldspar and biotite volcanic glass dust. Bentonitic clay layers have average thicknesses vary between 2 and 6 m. They are distributed by centimeter to decimeter levels of soft sandstone, sandy, and rich black mica. Sandstone is greywacke clay and carbonated cemented, matrix consisting of quartz, feldspars, biotite as major minerals, zircon, and glauconite as accessory minerals. They deposited in a marine, reduced, and confined environment. Mineralogical composition of bentonitic clay region of M’zila is as follows: (1) Clay minerals are represented by the montmorillonite with a small amount of kaolinite. (2) Non-clay minerals are composed mainly of quartz, albite, biotite, calcite, heulandite, chlorite, dolomite, and gypsum. Infrared spectroscopy shows that bentonitic clay has highlighted the presence of the disorderly a high temperature silica tridymite. Geochemistry of the major elements of M’zila bentonitic clay shows high a percentage of SiO2 and Al2O3. Chemical analysis shows that the 10, 12, 14 B 7, 4 A, and 4 clay layers are ferric clay; 11 and 3 layers are magnesian clay. Particle size analysis by sedimentation shows bentonitic clays are accrued mainly clay fractions to silt. Bentonitic clay deposit of M’zila has probably volcanic origin and deposited in a marine, reduced, and confined environment. 相似文献
6.
Hydraulic conductivities of fractured sandstone bore cores of 0.1 m in diameter are calculated using detailed characterization of the fracture geometry parameters determined using a resin casting technique. The accuracy of the measurements was about 0.25–1.25 μm with the image size used. The values of the effective fracture apertures vary between 10 μm and 50 μm. For modelling purposes the samples are sectioned serially, perpendicular to the flow direction along the cylinder axis. The hydraulic conductivity of individual slices is estimated by summing the contribution of the matrix (assumed uniform) and each fracture (depending on its length and aperture). Finally, the hydraulic conductivity of the bulk sample is estimated by a harmonic average in series along the flow path. Results of this geometrical upscaling compare favourably with actual conductivity measured in hydraulic and pneumatic experiments carried out prior to sectioning. This study shows that the determination of larger-scale conductivity can be achieved, based on the evaluation of fracture geometry parameters (e.g. fracture aperture, fracture width and fracture length), measured using an optical method, at least at the laboratory scale. 相似文献
7.
Salima Chakroun Wafa Mechti Mongi Herchi Mohamed Essghaier Gaied 《Arabian Journal of Geosciences》2018,11(3):60
Three mixtures (M1, M2, and M3) of the Eocene clay deposits were collected from Ain M’Dheker (Enfidha, Tunisia). These mixtures have been treated by hydrochloric acid in order to improve their physico-chemical characteristics. Optimum conditions for activation were conducted by varying several parameters such as the acid concentration, time, and temperature activation. The activation condition effect on surface area is studied. A representative raw (M3) and activated (AM3) mixtures were used in industrial application: Sunflower oil and Black 194 dyes (textile waste). M3 and AM3 were used to leach sunflower oil by varying the clay amount introduced. Results of the bleaching power of used samples were compared to that found by commercial bentonite imported from Germany (Tonsil), having a surface area of 725 m2/g. Indeed, an amount of 1% of AM3 gives a 60% decolorization similar to that found by commercial clay. Also, the ability of raw and activated clay to remove the dye (Acid Black 194) from effluent has been studied firstly at different pH and in second time by varying the adsorbent amount. Then, an amount of 0.025 g is sufficient to give a higher adsorption capacity for M3 than AM3. Consequently, Ain M’Dheker clay deposits can be use in other environmental application even without any treatment. 相似文献
8.
Geotechnical properties of carbonate sediments result from several factors such as the particular constituents comprising
the sediment, the mineralogy, fabric, and effective stress. Investigating the effects of increasing effective stress by mechanical
consolidation using permeability, porosity, and porometry determinations reveals fabric changes that could not be determined
in scanning electron micrographs. Porometry changes, determined using an image analyzer, are a function of matrix composition
and grain support. Samples that were predominantly matrix-supported exhibited an increase in pore numbers per unit area and
a pore size decrease resulting from consolidation. Samples composed predominantly of aragonite needle matrices displayed opposite
behavior. 相似文献
9.
William W. Sager William W. Schroeder J. Scott Laswell Kenneth S. Davis Richard Rezak Stephen R. Gittings 《Geo-Marine Letters》1992,12(1):41-48
A geophysical survey of the outer Missisippi-Alabama continental shelf revealed three types of topographic features: 1) reef-like mounds (RLM), 2) isobath-parallel ridges, and 3) shallow depressions. RLM appear to be bioherms. Their bases cluster in two isobath bands, 105 to 120 m and 74 to 82 m, implying the late Pleistocene-Holocene transgression was nonuniform. The deeper RLM probably formed during a slow sea level rise at the beginning of the deglaciation. An 11 ka BP C14 age was obtained from the summit of one, at a depth of 90 m. Depth relationships suggest the shallower RLM and most ridges formed about the time of the mid-deglacial Younger Dryas cooling episode. 相似文献
10.