Stratigraphy of the Cenomanian–Turonian Oceanic Anoxic Event OAE2 in shallow shelf sequences of NE Egypt     

Ahmed El-Sabbagh  Abdel Aziz Tantawy  Gerta Keller  Hassan Khozyem  Jorge Spangenberg  Thierry Adatte  Brian Gertsch 《Cretaceous Research》2011,32(6):705-722

Two shallow water late Cenomanian to early Turonian sequences of NE Egypt have been investigated to evaluate the response to OAE2. Age control based on calcareous nannoplankton, planktic foraminifera and ammonite biostratigraphies integrated with δ¹³C stratigraphy is relatively good despite low diversity and sporadic occurrences. Planktic and benthic foraminiferal faunas are characterized by dysoxic, brackish and mesotrophic conditions, as indicated by low species diversity, low oxygen and low salinity tolerant planktic and benthic species, along with oyster-rich limestone layers. In these subtidal to inner neritic environments the OAE2 δ¹³C excursion appears comparable and coeval to that of open marine environments. However, in contrast to open marine environments where anoxic conditions begin after the first δ¹³C peak and end at or near the Cenomanian–Turonian boundary, in shallow coastal environments anoxic conditions do not appear until the early Turonian. This delay in anoxia appears to be related to the sea-level transgression that reached its maximum in the early Turonian, as observed in shallow water sections from Egypt to Morocco.  相似文献   

Hydrogeophysical investigation of groundwater potential in the El Bawiti, Northern Bahariya Oasis, Western Desert, Egypt   总被引：1，自引：1，他引：0  

Mohamed El Kashouty  Aiman Abdel Aziz  Mamdouh Soliman  Hany Mesbah 《Arabian Journal of Geosciences》2011,5(5):953-970

The future development of agriculture, industry, and civil activity planned to be in the Western Desert. This strategy need to the groundwater resource. Vertical electrical soundings (VES) and electromagnetic (TEM) measurements conducted in the El Bawiti, northern Bahariya Oasis. The measurements give detailed information about the geometry of the different hydrogeological layers in the aquifer system and depth to them. A total of 22 VES and TEM were carried out within El Bawiti area. Thirty-one sub soil samples were collected from eight sites to determine the chemical characteristics and address the effects of lithogenic source and anthropogenic activity on them. The geoelectrical measurements and borehole information indicate the presence of five geoelectrical units, from top to base; the surface cover, sand and shale, upper aquifer (Nubian sandstone), sand and shale, and lower aquifer (Nubian sandstone). Surface cover was equally distributed in thickness and composed of dry sand, gravel, and clay deposits. The regional resistivity of the upper aquifer increased in the southwestern part and decline in the northern, eastern, southern, and western parts. The decline in the resistivity reflects the high water yields and potentiality, as well as low salinity. The resistivity of the lower aquifer increased due the northwestern part and the southwestern part. The information collected during this research provides valuable data for estimating the fresh- to brackish-water resources and for development of a groundwater management plan. The integrated analyses carried out represent a significant and cost-effective method for delineating the main aquifer in this area. In turn, future well locations can be placed with more confidence than before, in accordance with the evaluation of the potentiality of the groundwater aquifers in the area. The electrical conductivity of the soil ranges from 302 to 8,490 μS/cm, increases in the western and central-northern parts. It is attributed to the location from the salt-affected soils (playa), the relatively lower elevation units (depressions) and the position in landscape in the Oasis. Sodium adsorption ratio ranges from 0.44 to 11 and the exchangeable sodium ratio ranges from 0.11 to 5. The estimated magnesium hazard fluctuated below 50%. The statistical analyses were accomplished in soil chemistry and discussed.  相似文献   

Scenario Reduction Applied to Geostatistical Simulations     

Margaret Armstrong  Aziz Ndiaye  Rija Razanatsimba  Alain Galli 《Mathematical Geosciences》2013,45(2):165-182

Having a large number of geostatistical simulations of a mineral or petroleum deposit provides a better idea of its upside potential and downside risk; however, large numbers of simulated realizations of a deposit may pose computational difficulties in subsequent decision-making phases. Hence, depending on the specific case, there can be a need to select a representative subset of conditionally simulated deposit realizations. This paper examines and extends an approach developed by the stochastic optimization community based on stochastic mathematical programming with recourse and is discussed here in the context of mineral deposits while it is possibly suitable for other earth science applications. The approach is based on measuring the “distance” between simulations and the introduced distance measure between simulated realizations of a mineral deposit is based on the metal above a given set of cutoff grades while a pre-existing mine design is available. The approach is tested on 100 simulations of the Walker Lake data with promising results.  相似文献   

A Parametric Study on Stability of Open Excavations in Alluvial Soils of Lahore District, Pakistan     

Muhammad Irfan  Aziz Akbar  Mubashir Aziz  Ammad Hassan Khan 《Geotechnical and Geological Engineering》2013,31(2):729-738

Rapid urbanization and expansion of metropolitans in the developing world is pressing the need of tall structures with multiple basements. In several such projects, open land is available around excavation site and unsupported deep excavations by maintaining appropriate side slopes offer economical solution. In this research, subsoil stratigraphy of Lahore district was established to be comprising of a top clay stratum 1.5–8 m thick, followed by a sand layer. Considering subsoil data from several geotechnical investigation reports, the effect of four key parameters viz., cohesion of clay layer, friction angle of sand layer, thickness of clay layer at the top and slope inclination of underlying sand layer on safety factor of open excavations was studied. Six hundred twenty-five slope stability analyses were conducted by considering different geometries and soil properties. Based on the results of these analyses, a regression model was suggested to estimate safety factor of open excavations in similar stratigraphy which would be useful in feasibility studies and preliminary design of deep excavations. It was established that the clay layer cohesion was the most dominant contributor to safety factor.  相似文献   

利用NOAA-AVHRR数据分析1982-2001年间中国植被的动态变化(英文)   总被引：1，自引：0，他引：1  

HABIB Aziz Salim  陈晓玲  龚健雅  王海燕  张俐 《地球空间信息科学学报》2009,12(2):146-153

The authors derived the normalized difference vegetation index (NDVI) from the NOAA/AVHRR Land dataset, at a spatial resolution of 8km and 15-day intervals, to investigate the vegetation variations in China during the period from 1982 to 2001. Then, GIS is used to examine the relationship between precipitation and the Normalized Difference Vegetation Index (NDVI) in China, and the value of NDVI is taken as a tool for drought monitoring. The results showed that in the study period, China’s vegetation cover h...  相似文献   

中国夏季气候对植被覆盖的影响:1982～2001(英文)     

HABIB Aziz Salim  陈晓玲  龚健雅  张力 《地球空间信息科学学报》2009,(1)

In this paper, we apply lagged correlation analysis to study the effects of vegetation cover on the summer climate in different zones of China, using NOAA/AVHRR normalized difference vegetation index (NDVI) data during the time period from 1982 to 2001 and climate data of 365 meteorological stations across China (precipitation from 1982 to 2001 and temperature from 1982 to 1998). The results show that there are positive correlations between spring NDVI and summer climate (temperature and precipitation) in m...  相似文献   

The construction of a third-order secular analytical J-S-U-N theory by the Hori-Lie technique     

Abdel Aziz Bakry  Osman M. Kamel  Salwa M. Waziry 《Earth, Moon, and Planets》1993,63(1):29-66

We expand both parts, the principal and indirect, of the Hamiltonian function up to the third order in the masses for the four major planets Jupiter-Saturn-Uranus-Neptune. Accordingly we write down the secular terms ofF ₁,F ₂,F ₃ and the critical terms ofF ₁,F ₂ in terms of the canonical variables of H. Poincaré neglecting powers higher than the second inH, K, P, Q.  相似文献   

Kernel Principal Component Analysis for Efficient,Differentiable Parameterization of Multipoint Geostatistics   总被引：6，自引：5，他引：1  

Pallav Sarma  Louis J. Durlofsky  Khalid Aziz 《Mathematical Geosciences》2008,40(1):3-32

This paper describes a novel approach for creating an efficient, general, and differentiable parameterization of large-scale non-Gaussian, non-stationary random fields (represented by multipoint geostatistics) that is capable of reproducing complex geological structures such as channels. Such parameterizations are appropriate for use with gradient-based algorithms applied to, for example, history-matching or uncertainty propagation. It is known that the standard Karhunen–Loeve (K–L) expansion, also called linear principal component analysis or PCA, can be used as a differentiable parameterization of input random fields defining the geological model. The standard K–L model is, however, limited in two respects. It requires an eigen-decomposition of the covariance matrix of the random field, which is prohibitively expensive for large models. In addition, it preserves only the two-point statistics of a random field, which is insufficient for reproducing complex structures. In this work, kernel PCA is applied to address the limitations associated with the standard K–L expansion. Although widely used in machine learning applications, it does not appear to have found any application for geological model parameterization. With kernel PCA, an eigen-decomposition of a small matrix called the kernel matrix is performed instead of the full covariance matrix. The method is much more efficient than the standard K–L procedure. Through use of higher order polynomial kernels, which implicitly define a high-dimensionality feature space, kernel PCA further enables the preservation of high-order statistics of the random field, instead of just two-point statistics as in the K–L method. The kernel PCA eigen-decomposition proceeds using a set of realizations created by geostatistical simulation (honoring two-point or multipoint statistics) rather than the analytical covariance function. We demonstrate that kernel PCA is capable of generating differentiable parameterizations that reproduce the essential features of complex geological structures represented by multipoint geostatistics. The kernel PCA representation is then applied to history match a water flooding problem. This example demonstrates that kernel PCA can be used with gradient-based history matching to provide models that match production history while maintaining multipoint geostatistics consistent with the underlying training image.  相似文献   

Integration of ASTER and airborne geophysical data for mineral exploration and environmental mapping: a case study,Gabal Dara,North Eastern Desert,Egypt     

Kh. Gemail  N. M. Abd-El Rahman  B. M. Ghiath  R. N. Aziz 《Environmental Earth Sciences》2016,75(7):592

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Assessment of multi-scenario rockfall hazard based on mechanical parameters using high-resolution airborne laser scanning data and GIS in a tropical area     

Ali Mutar Fanos  Biswajeet Pradhan  Azlan Abdul Aziz  Mustafa Neamah Jebur  Hyuck-Jin Park 《Environmental Earth Sciences》2016,75(15):1129

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