Analysis of rainfall causal relationships in the Sudan

Monthly rainfalls of the main rainy period (April – October) in Sudan are quantitatively related to atmospheric factors which include vertical atmospheric motion and the depth of maritime SW winds. Other atmospheric properties which are studied in relation to rainfall include the thermal and moisture factors. From these specified factors a logical consideration of cause and effect is made with respect to rainfall over the Sudan as a whole. Multiple regression analysis has been used as a valuable tool in such analysis of causal relationships. It is also a useful technique by which to obtain reasonable estimates of rainfall for areas without rain gauges, and to assess the relative importance of causative factors of the rainfall amounts and spatial variations. Other statistical techniques used for examining the causal analysis are those of simple, partial and multiple correlation coefficients.     

The construction of a third order secular

In this part we find out the 24 equations of secular perturbation equations for the subsystem J-S-U-N. The solution of these equations by the Lagrange-Laplace procedure and the Eigen value Eigen vector is analysed. Also we refer to Hurwitz theorem to test stability.     

On the elimination of the critical term in a general first-order Uranus-Neptune theory

A solution of the Uranus-Neptune planetary canonical equations of motion through the Von Zeipel technique is presented. A unique determinging function which depends upon mixed canonical variables, reduces the 12 critical terms of the Hamiltonian to the set of its secular terms. The Poincaré canonical variables are used. We refer to a common fixed plane, and apply the Jacobi-Radau set of origins. In our expansion we neglected terms of power higher than the fourth with respect to the eccentricities and sines of the inclinations.     

Calcareous nannofossil biostratigraphy and paleoecology of the Cenomanian – Turonian transition in the Tarfaya Basin, southern Morocco

An abundant and diverse nannoflora occurs across the Cenomanian/Turonian (C/T) boundary at Tazra in the Tarfaya Basin of southern Morocco. The nannoflora of this sequence permits recognition of three biozones (CC10-CC12), three subzones (CC10a, CC10b and CC10c), and thirteen important nannolith bioevents previously reported from this interval elsewhere. The floral record shows erratic species abundance fluctuations that clearly vary with lithology and reflect at least in part preservational bias and diagenetic processes. In general, four dissolution resistant taxa are dominant: Watznaueria barnesae, Eiffellithus turriseiffelii, Eprolithus floralis, and Zeugrhabdotus spp. The late Cenomanian Zone CC10 marks a rapid excursion in ∂¹³C and is characterized by the successive extinction of four taxa, which are widely recognized as reliable biomarkers: Corollithion kennedyi, Axopodorhabdus albianus, Lithraphidites acutus, and Helenea chiastia. This interval is also marked by high species richness and high abundance of the tropical species Watznaueria barnesae, suggesting warm tropical waters. The subsequent ∂¹³C plateau and organic carbon-rich black shale deposition of the oceanic anoxic event (OAE2) is characterized by low species richness, but high nannofossil abundance, and peak abundance of the cool water and high productivity indicator Zeugrhabdotus spp., followed by the first peak abundance of cool water Eprolithus floralis. This interval correlates with the planktic foraminiferal diversity minimum and the Heterohelix shift, which marks the expansion of the oxygen minimum zone (OMZ). The C/T boundary is identified based on the FO of Quadrum gartneri, which is <1 m below the FO of the planktic foraminifer C/T marker Helvetoglobotruncana helvetica. In the early and middle Turonian, the two dominant species, tropical W. barnesae and cool water E. floralis, alternate in abundance and suggest fluctuating climatic conditions.     

Assessment of organic pollutants in coastal sediments, UAE

Twenty-five stations were selected along the UAE coastal region to delineate the distribution and to determine the source of total petroleum hydrocarbon (TPH), total organic carbon (TOC), total Kjeldhal nitrogen (TKN), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The concentrations of TPH ranged between 46 and 223 mg/kg and the level of TOC was in the range from 0.044 to 17.8 wt%, while TPAHs occupied the range of 5–102.2 μg/kg. On the other hand, TPCBs showed values between 60 and 205 μg/kg and TKN ranged from 104 to 1,073 mg/kg. The present study shows that the distribution of organic compounds in UAE sediments were within safe limits comparing with previous studies. The present study revealed that TOC can be used as an indicator of oil pollution in heavily oiled sediments. The highest values of TOC, TPH, TPAHs and TPCBs related to the stations covered in fine sand due to adsorption properties and the large surface areas of the grains. The evaporation of low-boiling point compounds from surface layers leads to the enrichment of sediments with a thick residual. Al Sharjah-1 exhibited the highest values of TPH and TOC at Ras Al-Khaima-5, Umm Al-Quwen-1 and Dubai-1, while the highest values of TPAHs were at KhorFakkan-9, the highest value of TPCBs was at Ajman-2, and the highest values of TKN were at KhorFakkan-1, KhorFakkan-6 and Dubai-1.     

Sequence stratigraphic evolution of The post-rift MEGASEQUENCE in The northern part of The Nile Delta basin,Egypt

The stratigraphic succession of the subsurface Pliocene-Quaternary post-rift megasequence in the north-central part of the Nile Delta includes the rock units; Kafr El-Sheikh Formation (Early-Middle Pliocene), El- Wastani Formation (Late Pliocene), Mit-Ghamr and Bilqas formations (Quaternary). These rock units were analyzed according to the sequence stratigraphic principles to construct their stratigraphic architecture and discuss the depositional events influencing their evolution. Accordingly, seven 3rd order depositional sequences were encountered, of which six 3rd order seismic depositional sequences (sequences 1–6) are found in the Early–Middle Pliocene Kafr El-Sheikh Formation, whereas sequence-7 includes the Quaternary rock units. Sequences 1 and 7 were further subdivided, on the basis of high-resolution sequence stratigraphy into 8 and 11 4th order subsequences respectively. The results of the sequence stratigraphic analyses suggested that the depositional evolution of the examined Pliocene-Quaternary megasequence represents a complete prograding depositional phase during the Nile Delta history. The lower part of Kafr El-Sheikh Formation (sequences 1, 2, 3 and 4) was deposited as a thick outer marine shelf succession over which the younger rock units were deposited. However, the depositional sequences 5 & 6 of Kafr El-Sheikh Formation and the lower parts of El-Wastani Formations may indicate a deposition within active prograding prodelta sub-aqueous deltaic-subenvironments. The upper parts of El-Wastani Formation were deposited as a constructive delta-front pushing its way northward. The Pleistocene Mit-Ghamr Formation was evolved as a direct result of a huge fluvial input, organized as coalescing laterally extensive sand-rich bars. These were laid-down by active fluvial distributary streams that dominated the delta plain as the final phases of the present deltaic subaqueous environments.     

Geochemical and stable isotopic studies of Gulf of Suez’s hot springs, Egypt

The Gulf of Suez region is one of the most interesting geothermal areas in Egypt because of the high temperatures of its springs.The eastern and western shores of the Gulf of Suez are characterized by superficial thermal manifestations including a cluster of hot springs with varied temperatures.Variations of deuterium and oxygen-18 concentrations in thermal waters have been used to aid in describing the source of recharge in the Gulf of Suez hot springs.Isotope and geochemical data for the Gulf of Suez thermal waters suggest that recharge to the hot springs may not be entirely from the Gulf of Suez water,but possibly from the meteoric water that comes from areas of higher altitude surrounding the hot springs.     

Investigation of groundwater potentiality in the eastern part of Qena,central Eastern Desert,Egypt, using 2D homogeneous function method

The present study represents an application of the 2D homogeneous function method to investigate the near-surface groundwater potentiality to the east of Qena town, Egypt. The homogeneous function automatically inverts first arrival refractions to derive a 2D velocity distribution, which involves seismic boundaries. A complex set of observed refracted traveltimes along four seismic profiles (12 spreads) is used to construct refraction velocity field section and structural section. Such sections allow viewing the complex layered structure and delineating its boundaries and faults. The interpreted geoseismic layers were traced, according to their own gradients and velocity ranges. The resultant models were successful in fulfilling the proposed objective, as they provide: (1) the required details on the delineation of the subsurface layers, where three geoseismic layers with different ranges of velocities were detected; (2) determination of the thickness and the inversion boundary of water-bearing layer; and (3) detection of normal and reverse faults with displacement of about 10–40 m and variable dipping directions. The obtained result was found to be completely compatible with the information gained from identified boundaries of the nearby borehole.     

Hornblende gabbros of Wadi Az Zarib area,Central Eastern Desert,Egypt: opaque mineralogy,geochemistry, tectonic setting,and petrogenesis

A small intrusive fresh gabbroic mass intrudes the Neoproterozoic metasediments and Dokhan volcanics of Wadi Az Zarib area, Central Eastern Desert. It is composed of hornblende gabbros and leuco-hornblende gabbros. Their petrography, opaque mineralogy, and geochemistry are addressed to elucidate their tectonic setting and petrogenesis. They represent a subduction-related calc–alkaline magma that evolved in an island arc setting. In terms of maturity, the supposed arc represents an intermediate stage between continental arc and active continental margin. Thermobarometry and physical–chemical data of the parent magma as deduced from compositions of amphiboles, biotite, and plagioclase indicate crystallization temperatures of 931–825 °C at pressures of 6.16–4.01 kbar and H₂O_melt of 6.4–5.2 wt%. Data, as presented, argue in favor of fractional crystallization mechanism to be accounted to the present suite to interpret the observed variations. The evolution of the suite from hornblende gabbros to leuco-hornblende gabbros was accompanied by decreasing of MgO, CaO, Cr, and Ni with simultaneous increasing of Al₂O₃, TiO₂, Na₂O, K₂O, Ba, Rb, Sr, La, and Ce. Residuals calculated during mass balance fractional crystallization modeling suggest that brown and green hornblendes are the main fractionated phases which derived the melt composition towards the leuco-hornblende gabbros.     

Upgrading of the inverse slope method for quantitative interpretation of earth resistivity measurements

The present study is an attempt to upgrade the previously used semi-analytical inverse slope method. The upgrade method was applied to the interpretation of VES’s measured with different electrode arrays in two and three layers laboratory tank model. Then the method was applied on VES’s measured at different sites of different geologic conditions. The study showed that the inverse slope method is a quick method for obtaining depths to interfaces. The method can be implemented on a hand-held calculator or more efficiently on a small microcomputer where the data can be processed at a faster rate than that of conventional data acquisition systems. This allows the method to be potent tools for infield data analysis and more cost effective to assess the success of a sounding on-the-spot and modify the experimental set-up as appropriate. The comparison between the results obtained from this method and the traditional digital computerized methods indicated that the geoelectrical models derived from inverse slope method have a good correlation with the actual model. Also, when applying the method on VES’s measured by using Schlumberger and Wenner arrays at areas of different geologic setting, gave results in comfortable with the actual lithology obtained from the lithologic data of the neighboring wells. The results obtained from the lab experiment and field survey indicated that the inverse slope method has the potential to be applied on VES data collected with any electrode array, the advantage that is not available with all the traditional interpretation methods available nowadays.