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1.
Dorra Tanfous Amri Mourad Bédir Mohamed Soussi Hajer Azaiez Lahoussine Zitouni M. Hédi Inoubli Kamel Ben Boubaker 《Comptes Rendus Geoscience》2005,337(7):703-711
Seismic and sequence stratigraphy analyses, petroleum-well control and surface data studies of the Majoura–El Hfay region in the Central Atlas of Tunisia had led to identify and calibrate Jurassic seismic horizons. Seismic stratigraphic sections, seismic tectonics analyses, isochron and isopach mapping of Jurassic sequences show a differentiated structuring of platform and depocentre blocks limited by deep-seated NE–SW, north–south east–west and NW–SE faults intruded by Upper Triassic salt. The early salt migration seems to have started by the platform fracturing during the Lower Liassic rifting event. These movements are fossilized by thickness variations of Jurassic horizons, aggrading and retrograding onlap and toplap structures between subsiding rim-syncline gutters and high platform flanks intruded by salt pillows and domes. The salt migration is also attested by Middle and Upper Jurassic space depocentre migrations. Around the Majoura–El Hfay study blocks bounded by master faults, Triassic salt have pierced the Cretaceous and Tertiary sedimentary cover in a salt diapir extrusion and salt wall structures. To cite this article: D. Tanfous Amri et al., C. R. Geoscience 337 (2005). 相似文献
2.
Khouloud Gader Ahlem Gara Marnik Vanclooster Slaheddine Khlifi Mohamed Slimani 《水文科学杂志》2020,65(8):1300-1315
ABSTRACT Predicting the impacts of climate change on water resources remains a challenging task and requires a good understanding of the dynamics of the forcing terms in the past. In this study, the variability of precipitation and drought patterns is studied over the Mediterranean catchment of the Medjerda in Tunisia based on an observed rainfall dataset collected at 41 raingauges during the period 1973–2012. The standardized precipitation index and the aridity index were used to characterize drought variability. Multivariate and geostatistical techniques were further employed to identify the spatial variability of annual rainfall. The results show that the Medjerda is marked by a significant spatio-temporal variability of drought, with varying extreme wet and dry events. Four regions with distinct rainfall regimes are identified by utilizing the K-means cluster analysis. A principal component analysis identifies the variables that are responsible for the relationships between precipitation and drought variability. 相似文献
3.
Harold Clénet Georges Ceuleneer Patrick Pinet Bénédicte Abily Yves Daydou Esther Harris Isma Amri Céline Dantas 《Lithos》2010,114(3-4):265-281
Using the HyMap instrument, we have acquired visible and near infrared hyperspectral data over the Maqsad area of the Oman ophiolite (~ 15 × 60 km). This survey allowed us to identify and map the distribution of clinopyroxene-rich cumulates (inter-layered clinopyroxenites and wehrlites) whose occurrence was previously undocumented in this area. The cumulates reach several hundred meters in thickness and crop out at distances exceeding 15 km on both sides of the Maqsad former spreading centre. They occur either in mantle harzburgites, as km-sized layered intrusions surrounded by fields of pegmatitic dykes consisting of orthopyroxene-rich pyroxenite and gabbronorites, or at the base of the crustal section where they are conformably overlain by cumulate gabbros. These ultramafic cumulates crystallized from silica- and Mg-rich melts derived from a refractory mantle source (e.g. high Cr#, low [Al2O3], low [TiO2]). These melts are close to high-Ca boninites, although, strictly speaking, not perfect equivalents of present-day, supra-subduction zone, boninites. Chemical stratigraphy reveals cycles of replenishment, mixing and fractional crystallization from primitive (high Mg#) melts, typical of open magma chambers and migration of inter-cumulus melts. The TiO2 content of clinopyroxene is always low (≤ 0.2 wt.%) but quite variable compared to the associated pegmatites that are all derived from a source ultra-depleted in high field strength elements (HFSE). This variability is not caused by fractional crystallization alone, and is best explained by hybridization between the ultra-depleted melts (parent melts of the pegmatites) and the less depleted mid-ocean ridge basalts (MORB) parent of the dunitic–troctolitic–gabbroic cumulates making up the crustal section above the Maqsad diapir.We propose that, following a period of magma-starved spreading, the Maqsad mantle diapir, impregnated with tholeiitic melts of MORB affinity, reached shallow depths beneath the ocean ridge. This diapir induced melting of the formerly accreted and hydrothermally altered lithosphere. At this stage, these boninitic-like lithospheric melts crystallized as pegmatitic dykes. As the diapir continued to rise, the amount of MORB reaching shallow depths increased, together with the surrounding temperature, leading to the formation of magma chambers where the crystallization of layered cumulates became possible. These cumulates remained rich in pyroxene and devoid of plagioclase as long as the contribution of MORB-derived melts was moderate relative to the lithospheric-derived melts. As the contribution of MORB to the refilling of the magma chamber increased, gabbroic cumulates started to crystallize. 相似文献
4.
Sultan Al-Yahyai Abeer Aulad Thani Noura Al-kaabi Khalifa Al-Sudairi Badriya Al-Mawali Issa Al Amri 《Arabian Journal of Geosciences》2017,10(4):76
An accurate tropical cyclone track and intensity forecast is very important for disaster management. Specialized numerical prediction models have been recently used to provide high-resolution temporal and special forecasts. Hurricane Weather Research and Forecast (HWRF) model is one of the emerging numerical models for tropical cyclone forecasting. This study evaluates the performance of HWRF model during the post monsoon tropical cyclone Nilofar on the north Indian Ocean basin. The evaluation uses the best track data provided by the Indian Meteorological Department (IMD) and the Joint Typhoon Warning Centre (JTWC). Cyclone track, central pressure, and wind speed are covered on this evaluation. Generally, HWRF was able to predict the Nilofar track with track error less than 230 km within the first 66 h of forecast time span. HWRF predicted more intense tropical cyclone. It predicted the lowest central pressure to be 922 hPa while it reached 950 hPa according to IMD and 937 hPa according to JTWC. Wind forecast was better as it predicted maximum wind speed of 122 kt while it reached 110 and 115 kt according to IMD and JTWC, respectively. 相似文献
5.
Kamel Amri Ghilles Rabai Imene Meriem Benbakhti Mohamed Nadir Khennouche 《Arabian Journal of Geosciences》2017,10(4):87
Djelfa area in the central Saharan Atlas is characterized by its high lithological diversity with different facies from the Triassic to the Tertiary. The lack of published geological maps of the region (Djelfa) prompted us to test specific processing of satellite images (ratio bands, principal component analysis) in order to establish a lithological discrimination of the region. Several treatments allowed us to map the lineaments highlighting the various tectonic structures of the region. The combination of field and remote sensing data pointed out the double influence of the E-W Eocene and N-S Miocene phases in the structuration of these regions. As a large part of the Djelfa area is inaccessible, the obtained results undeniably contribute to a better understanding of the local geology. 相似文献
6.
Sedimentological and biostratigraphic analysis of Campanian–Maastrichtian reduced series of the J. Serj permitted to characterize two episodes of submarine erosion. The first is pre-Upper Maastrichtian (Rosita contusa zone), the second is pre-Upper Palaeocene (Morozovella velascoensis zone). Thus, two type-1 boundary surfaces are distinguished. These surfaces limit three stratigraphic intervals in apparent continuity. Syn-sedimentary tectonic activity is attested by gravity deposits or processes (conglomerates, slumps). To cite this article: A. Amri et al., C. R. Geoscience 337 (2005). 相似文献
7.
Geotectonics - The purpose of this paper is to characterize the configuration of northern Tunisia’s basin during the Cretaceous on the basis of abundant slump folds and frequent... 相似文献
8.
Jillian Lean Sim Ooi Gary A. Kendrick Kimberly P. Van Niel Yang Amri Affendi 《Estuarine, Coastal and Shelf Science》2011
Seagrasses are habitats with significant ecological and economic functions but we have limited knowledge of seagrasses in Southeast Asia, the hypothesized centre-of-origin for tropical seagrasses. There have been only 62 ISI-cited publications on the seagrasses of Southeast Asia in the last three decades and most work has been in few sites such as Northwest Luzon in the Philippines and South Sulawesi in Indonesia. Our understanding of the processes driving spatial and temporal distributions of seagrass species here has focussed primarily on backreef and estuarine seagrass meadows, with little work on forereef systems. We used Pulau Tinggi, an island off the southeast coast of Peninsular Malaysia, as an example of a subtidal forereef system. It is characterized by a community of small and fast growing species such as Halophila ovalis (mean shoot density 1454.6 ± 145.1 m−2) and Halodule uninervis (mean shoot density 861.7 ± 372.0 m−2) growing in relatively low light conditions (mean PAR 162.1 ± 35.0 μmol m−2 s−1 at 10 m depth to 405.8 ± 99.0 μmol m−2 s−1 at 3 m water depth) on sediment with low carbonate (mean 9.24 ± 1.74 percentage dry weight), organic matter (mean 2.56 ± 0.35 percentage dry weight) and silt-clay content (mean 2.28 ± 2.43 percentage dry weight). The literature reveals that there is a range of drivers operating in Southeast Asian seagrass systems and we suggest that this is because there are various types of seagrass habitats in this region, i.e. backreef, forereef and estuary, each of which has site characteristics and ecological drivers unique to it. Based on our case study of Pulau Tinggi, we suggest that seagrasses in forereef systems are more widespread in Southeast Asia than is reflected in the literature and that they are likely to be driven by recurring disturbance events such as monsoons, sediment burial and herbivory. 相似文献
9.
Dorra Tanfous Amri Ferid Dhahri Mohamed Soussi Hakim Gabtni Mourad Bédir 《Journal of Earth System Science》2017,126(7):104
The Gafsa and Chotts intracratonic basins in south-central Tunisia are transitional zones between the Atlasic domain to the north and the Saharan platform to the south. The principal aim of this paper is to unravel the geodynamic evolution of these basins following an integrated approach including seismic, well log and gravity data. These data are used to highlight the tectonic control on the deposition of Jurassic and Lower Cretaceous series and to discuss the role of the main faults that controlled the basin architecture and Cretaceous–Tertiary inversion. The horizontal gravity gradient map of the study area highlights the pattern of discontinuities within the two basins and reveals the presence of deep E–W basement faults. Primary attention is given to the role played by the E–W faults system and that of the NW–SE Gafsa fault which was previously considered active since the Jurassic. Facies and thickness analyses based on new seismic interpretation and well data suggest that the E–W-oriented faults controlled the subsidence distribution especially during the Jurassic. The NW–SE faults seem to be key structures that controlled the basins paleogeography during Late Cretaceous–Cenozoic time. The upper Triassic evaporite bodies, which locally outline the main NW–SE Gafsa fault, are regarded as intrusive salt bodies rather than early diapiric extrusions as previously interpreted since they are rare and occurred only along main strike-slip faults. In addition, seismic lines show that Triassic rocks are deep and do not exhibit true diapiric features. 相似文献
10.
Wadi Afara Héouine area (Tahifet, Central Hoggar) is marked by the existence of very diversified lithologies affected by big submeridian accidents, of which Wadi Afara Héouine, who represents a "linear discontinuity" on near 80 km forming a morphological limit which separates, a strongly gneissic domain (Oua Hellèdjène) of a domain with metasedimentary dominant (Aghefsa). Lithologies not described in the former works were defined by the application of specific treatments (color composite, band ratios, and selective PCA). They also allow us to suggest some modifications to the geologic map of Tahifet. Directional filters associated to the previous treatments helped us in the elaboration of lineament map which accentuates the various accidents affecting the region. It seems clearly that treatments applied to the images ETM contribute in an undeniable way to the geologic study of this region especially since a big part of this region is inaccessible 相似文献