Khalid A. Almalki

Incipient seafloor spreading segments: Insights from the Red Sea

Crustal-scale forward models of marine satellite potential field data suggest that the Red Sea comprises a single segment of ocean crust, which extends along ~60% of the Red Sea. The segment “tips” are bounded by continental crust, and there is no evidence for transforms at the segment terminations at the south. These observations indicate that ocean crust formation does not necessarily occur in response to wholesale tearing or “unzipping” of continental lithosphere nor is it necessarily controlled by preexisting transform faults. Ocean crust initiation occurs as a series of isolated segments that coalesce as the basin evolves. The recognition of this process in an orthogonal extension setting is comparable to spreading segmentation in modern ocean systems generated at a highly oblique convergent margin, suggesting that oceanic crust segmentation is not controlled by kinematic boundary conditions. The Red Sea may represent a combination of incipient type I and type II passive margins development.

Introduction to the carbonate microfacies of the Farasan Islands, southern Red Sea

Microfacies analysis of the Farasan Islands sediments was carried out to unravel the depositional environment and evolution of the area. Thin section petrographic studies were carried out to expand on the field identifications, to study the composition and to classify the Farasan Islands rock units. Sedimentological characteristics and depositional settings were also established. Several fossil assemblages have been identified, including Forams, Algae, Corals, Mollusks, Ostrocods, and Ooids. The most common diagenesis processes observed were dissolution and replacement by gypsum and anhydrite. The carbonates of Farasan Islands show normal shallow marine processes. Shale and anhydrite sequences were deposited most likely in subtidal to open marine environments. Progressive shallowing of the depositional environment is illustrated by the evolution of sedimentary facies in the Farasan Islands from low energy subtidal to open marine and finally to high energy at the top of the sequence. Field observation of palaeoshorelines may reflect the control of sea-level changes on reef formations during the Plio-Pleistocene time in the Red Sea.

Mineralogy and spectroscopy of Owen Group sandstones, Australia: implications for the provenance, diagenesis, and origin of coloration

Mineralogical studies were conducted on sandstones of Late Cambrian-Early Ordovician Owen Group, southern West Coast Range, Tasmania, Australia. Several samples were analysed using conventional thin section and point counting techniques, while others were further analysed under a Scanning Electron Microscope with back scattering and Energy Dispersive X-ray Spectroscopy capabilities. The result of petrographic analyses includes provenance, possible sources and controls over coloration in sandstone samples. The sandstones are mainly comprised of quartz, mica, lithic grains (volcanic, metamorphic and sedimentary), clays, zircon, tourmaline, leucoxene, rutile, and chert grains. These were derived from a Proterozoic Tyennan metamorphic and a Middle Cambrian Mount Read Volcanic provenance. Following deposition, sediments underwent severe diagenesis including quartz overgrowth, iron coatings, haematite, chlorite and sericite alterations, linings and cements. Multi-phase haematite-related diagenesis is present and late stage hydrothermal fluid alterations assemblages have severely altered and colored the sediments.

Improving geological mapping of the Farasan Islands using remote sensing and ground-truth data

ABSTRACT We integrated satellite imagery (Landsat-8) with ground-truth data to produce a detailed and complete geological map of the Farasan Islands, off the Red Sea coast of Saudi Arabia at a scale of 1:100,000. This new map improves upon past efforts by expanding the mapped lithologies on the islands into four categories. We used different techniques to enhance this lithological differentiation, including band combination with ratio stretching and supervised classification techniques based on direct field validation. The former was used to distinguish differences in reflectance values across sets of bands to create a classification image from typical reflectance patterns. The geological feature boundaries were constrained by open-source high-resolution satellite imagery (WorldView-2) as well as field observations. The resulting map clearly distinguishes between different geomorphic and geologic features, including lineaments and lithologies. As the Farasan Islands are relatively remote and not easily accessible, with an area of 739 km2, these imagery-analysis techniques were an effective tool for using remote sensing data to produce new and better mapping products of this important area.

Role of climate on sediment deposition: A study of Cambrian-Ordovician, Tasmania, Australia

The quantification of the volume and spatial disposition of pores, fractures or cleats and minerals in coals is a primary and fundamental requirement for CBM reservoir evaluation. Coal as a CBM reservoir is a complex polymeric material with complex porous structures which are important for flow pathway that determine the permeability and producibility of coalbed methane. The CT scan computed tomography is a non-destructive technique that can provide quantitative detection and visualization of interior structure of rocks in 3D within opaque objects. This paper will inform several applications illustrate the possibilities, specific advantages and limitations of CT for non-destructive coal characterization in describing the fracture and cleat characteristics including fracture-size patterns, network geometries in coal which is very useful in quantified and 3D visualization of the spatial disposition of minerals, pores and fractures in coals. As with every technique there are always some restrictions that can happen, however the CT scan technique proved to be an emerging non-destructive analysis which gives promising results in CBM exploration activitiesPollution of groundwater has become a major environmental problem. Anthropogenic impacts on groundwater within different zones of Abeokuta, Southern Nigeria were evaluated. The study area was divided into four zones; Crowded, Market, Residential and Industrial areas. Groundwater samples were randomly collected from hand dug wells and boreholes and analysed for pH, electrical conduitivity (EC) and total dissolved solids (TDS). The samples were also analysed for selected trace metals using ICP-NS and major anions and cations. Results of the Physicochemical parameters were in the range of 67 – 649 ppm for TDS; 6.6 – 8.9 forIntroduction and Methods The drainage structures in Ibadan Metropolis are depocenter for both industrial and domestic wastes/effluents [1] contributing potentially harmful elements (PHE) into stream sediments. This study examine the trace metal content in the sediments and evaluate their origin, pollution status and their bioavailability in the environment. Two hundred and thirty three (233) samples from Agricultural, Industrial; Old city, and new city zones (zone 1,2,3,4) respectively; were analyzed using XRD and inductively coupled plasma-mass spectrometry (ICP-MS) and sequential leaches. Discussion of Results Kaolinite, illite, montmorillonite and quartz were the dominant minerals. The PHEs concentrations for Cu (18.30513.00), Pb (40.30-5140.00), Zn (80.90-2450.00), As (0.207.10), Cd (0.08-24.40), Cu-Pb-Zn-Cd revealed highest concentrations in the old city (densely populated) and industrial areas of the city respectively. Pollution Load Index (PLI) values for zones 1 to 4 include PLI-127, 471, 582, 512, respectively indicating polluted sediments and metal sources link to human and landuse activities. Percentages of Pb, Zn and Cd ranged correspondingly from 26.4-43.5; 25.5-36.9 and 17.0-51.0 in the exchangeable phase indicating their bioavailability in the environment. Cu, Pb, Zn, Cd and Ni concentrations in all the zones exceeded the threshold values in the sediment quality guidelines (SQGs) suggesting that the sediments were polluted [2].