Vol. 15 Issue 2
M. Abou Auf and A.M. Gheith
Field examination, sedimentological and paleontological investigations have been carried out on the clastic Shumaysi Formation exposed east of Jeddah region.
Paleoenvironmental interpretation of pre rift basin sediments shows that fluviatile environment in flood plain stage is suggested for the deposition of the lower Shumaysi Formation. While the middle Shumaysi Formation was deposited in fresh water lake environment.
The upper Shumaysi Formation (syn rift sediments) represents an early transgressive marine environment with final freshwater lake in between the eruptive centres as indicated by the enrichment with volcanic tuffs and precipitated silica. Finding of planktonic foraminiferal (Globigernoides) fossils at the bottom and mollusca fauna with plant remains (Oogonia) at the top gives an Oligocene-Early Miocene age for the upper Shumaysi Formation.
The heavy mineral suite is dominated by ultrastable constituents; zircon and rutile. The gross mineralogy of the heavy mineral assemblage remains unchanged throughout the succession. It reflects deeply weathered igneous rocks with dominant flat relief conditions in (he Red Sea area during that time.
Shumaysi Formation appears to preserve a much earlier rifting history where Late Oligocene-Early Miocene sedimentary rocks are the earliest record of Red Sea rifling.
A. R. Kacimov and Yu. V. Obnosov
New analytical solution to the problem of fluid flow in a porous reservoir composed by rectangular blocks is presented. The Muskat linear, five-point, and chess-type patterns of injection extraction wells (lEW) are obtained as special cases of this solution. Streamlines, isochrones, breakthrough curves are evaluated in tenns of Lite model of pure advection. Effective conductivity of these patterns is obtained explicitly and compared with Muskat's values which occurred to be good approximations of the rigorous formulae. Numerical procedure of particle tracking is verified on the Rankine flow pattern for a pair of lEW placed in an uniform groundwater flow and the Polubarinova-Kochina solution for a pumping well in an aquifer with a circular inhomogeneity. Applications to a network of octagonal honey-comb blocks and filled fractures-orifices are discussed.
M.S.Omar
X-ray diffraction method has been used to determine the crystal structure of the ternary compound Cu2GeSe3. A complete powder data is presented; and their analysis by Ito's method gives a Triclinic superlattice for the bended sphalerite unit cell of Cu2GeSe3 compound, with the lattice constants of a = 3.9381 A° , b = 22.3796 A° and c =11.5626 A° and the angles are α=90.039°, β =89.592° and γ= 89.945°.
Shafik I. Abdel.Aal, Ragaa E.A. Sabrah, Rafaat K. Rabie, and Hago M. Abdel Magid
Appraisal of groundwater used for irrigation in El-Gassim region of Central Saudi Arabia was made by chemically analysing 217 representative water samples.
Based on previous water criteria guidelines and a modification by us, the data obtained were intensively processed and transformed. Accordingly, water quality and suitability maps were developed under the conditions of this study with special focus on wheat production.
The water quality parameters investigated revealed the following:
1) water salinity ranged from 210-8200 ppm with an average of 2375 ppm (i.e. between 16.6 and .83 t ha-1 of salt deposited in soil per season for wheat and alfalfa cultivation);
2) extensive water extraction caused a significant increment in SO=4 I Cl- ratio;
3) accumulation of reactive constituents such as H2S, FeS and SO=4 caused corrosion and damaged the pivot pipeline and
4) irrigation water contributed to soluble potassium which amounted to 475 and 2500 kg K2S04 ha-1 season-1 for wheat and alfalfa crops, respectively.
M.I. Soliman and A.A. Khedr
The anatomical characteristics of leaves of seven xerophytic species namely: Artemisia monosperma, Zilla spinosa, Farsetia aegyptia, Launaea spinosa, Zygophyllum coccineum, Panicum turgidum, and Lasiurus hirsutus are described. Artemisia monosperma, Zilla spinosa and Farsetia aegyptia develop multilayered palisade tissue on both sides of their leaves with compact cells and narrow inter-cellular spaces. The leaves of Zygophyllum coccineum show large, highly vacuolated, water-storage cells lacking chloroplasts in addition to the photosynthetic mesophyll. Panicum turgidum, Lasiurus hirsutus, Zilla spinosa and Farsetia aegyptia show slightly sunken stomata, whilst in Launaea spinosa and Artemisia monosperma stomata are deeply sunken.
Monier M. Abd El-Ghani
The study deals with the distribution, habitats, and ecological characteristics of natural vegetation along a transect crossing the central part of Hijaz Mountains, Saudi Arabia. Fifty stands were classified on the basis of leading dominant species, using agglomerative cluster analysis, into five distinct and recognizable vegetation groups (vegetation types). A total of 86 plant species were recorded. The present study provides evidence that the vegetation shows discernible zonation. The annuals increase, and the biennials and perennials decrease along the elevation gradient from lower to higher elevations. This appears to be correlated, at least partly, with altitude. Species diversity varies from one vegetation group to the other as well as between stands of the same group. The vegetation type of Ficus salicifolia is the most widespread, diversified and consequently, the most stable vegetation cover in the study area; it, therefore, represents the climatic climax community. Human interference has a prominent role in changing the physical environment and inevitably destroys the precarious balance among the components of the ecosystem. The environment has deteriorated, and retrogressive changes in the vegetation are recorded.
M.M. Dorgham and M.M. Hussein
Seasonal changes in zooplankton assemblages in Doha Harbour, a neritic area in the Arabian Gulf were studied from December 1987 to November 1988 in relation to the seasonal variations of temperature, salinity and nutrients. The zooplankton community in the study area was characterized by low species diversity and a relatively low numerical density relative to other areas in the Gulf. High salinity seems to be a dominant factor affecting growth and the breeding cycles of the abundant zooplankton species. The average population densities ranged from a maximum of 47051m3 in June to a minimum of 993/m3 in November. Copepods were the major component, in the ratio of I: 1.7: 5.5 harpacticoids: calanoids: cyclopoids. This ratio showed a departure from that usually observed in warm waters. Some deep-water species were occasionally recorded indicating the possibility of adaptation of Indo-Pacific species to the area.
Mohammad I. Sway and Ahmad S. Abushamleh
The complexation of 18-crown-6 with Ag⁺, Pb²⁺, Cd²⁺, Cu²⁺, Co²⁺ and Ni²⁺ in methanol-water solvents has been studied using a conductometric technique. Log K, ∆H°, ∆S° values are determined in 0%- 90 w% methanol-water at several temperatures in the range 288-308K. The measured stability constants and thermodynamic parameters were found to be solvent dependent. There is an inverse relationship between the stability constants of the complexes and Gutmann donicity of the solvents. The measured molar conductivities, Λ, Pb²⁺, Ag⁺, and Cd²⁺ complexes of 18-crown-6, were observed to decrease significantly for mole ratios, [L]₀/ [Mⁿ⁺]₀, close to unity while those of Cu²⁺, Co²⁺ and Ni²⁺ complexes were decreased less significantly. The measured molar conductivities have been analysed using a 1:1 stoichiometric model. The stability constant K, and the limiting molar conductivity, Λc, for each 1:1 complex have been determined from the measured molar conductivities by using a non-linear least-squares analysis. In 90% methanol-water solvents used, the binding sequence, based on the value of log K at 298 K, was found to be Pb²⁺ > Ag⁺ > Cd²⁺ > Cu²⁺ > Co²⁺ > Ni²⁺. The significance of the determined values of the present thermodynamic parameters has been discussed in terms of solvent medium and relative sizes of cations and crown ether cavity.
M. Abou Auf and A.M. Gheith
Field examination, sedimentological and paleontological investigations have been carried out on the clastic Shumaysi Formation exposed east of Jeddah region.
Paleoenvironmental interpretation of pre rift basin sediments shows that fluviatile environment in flood plain stage is suggested for the deposition of the lower Shumaysi Formation. While the middle Shumaysi Formation was deposited in fresh water lake environment.
The upper Shumaysi Formation (synrift sediments) represents an early transgressive marine environment with final freshwater lake in between the eruptive centres as indicated by the enrichment with volcanic tuffs and precipitated silica. Finding of planktonic foraminiferal (Globigerinoides) fossils at the bottom and mollusca fauna with plant remains (Oogonia) at the top gives an Oligocene-Early Miocene age for the upper Shumaysi Formation.
The heavy mineral suite is dominated by ultrastable constituents; zircon and rutile. The gross mineralogy of the heavy mineral assemblage and remains unchanged throughout the succession. It reflects deeply weathered igneous rocks with dominant flat relief conditions in the Red Sea area during that time.
Shumaysi Formation appears to preserve a much earlier rifting history where Late Oligocene-Early Miocene sedimentary rocks are the earliest record of Red Sea rifting.
A.R. Kacimov and Yu. V. Obnosov
New analytical solution to the problem of fluid flow in a porous reservoir composed by rectangular blocks is presented. The Muskat linear, five-point, and chess-type patterns of injection-extraction wells (IEW) are obtained as special cases of this solution. Streamlines, isochrones, breakthrough curves are evaluated in terms of the model of pure advection. Effective conductivity of these patterns is obtained explicitly and compared with Muskat's values which occurred to be good approximations of the rigorous formulae. Numerical procedure of particle tracking is verified on the Rankine flow pattern for a pair of IEW placed in an uniform groundwater flow and the Polubarinova-Kochina solution for a pumping well in an aquifer with a circular inhomogeneity. Applications to a network of octagonal honeycomb blocks and filled fractures-orifices are discussed.