Petrographic and geochemical study of Precambrian and Paleozoic rocks in the western Anti-Atlas belt, Morocco: Facies, weathering, provenance and economic exploitation.

Detrital and volcanic-detrital rocks from the Ifni Buttonhole and Lakhssas Plateau were analyzed to determine their provenance, compositional maturity, and alteration source. Geochemically, the sediments were classified as arkoses, lithic arenites, grauwackes, sandstones, lithic arenites, and Fe-rich sands, indicating low compositional and mineralogical maturity. A high average SiO2 concentration and low Al2O3 were consistent with a low abundance of shale and clay components. The geochemical signatures of the detrital and volcano-detrital (RDVD) rocks indicate that they have undergone a moderate to low degree of chemical alteration. The CIA study also suggests that the granitic, granodioritic rocks represent the source provenance which, during weathering and transport, supplied the detritus to the supra-crustal units. The major trace element data suggest that these rocks are largely derived from felsic igneous rocks, namely granitoids, with a minor contribution from intermediate sources. The carbonate rocks do not represent a wide variety of facies: dolomitic limestone, calcareous limestone, and calcaro-dolomitic chert. Calcitic and dolomitic samples show a linear increase in SiO2, regardless of their CaO/LOI ratio values, which remain relatively constant. The highest SiO2 contents are observed in the calc-dolomitic chert. Geochemical analysis of RDVD from the Ifni buttonhole determined their origin, maturity, and alteration. Major oxides decreased with higher silica content, indicating quartz control. Samples, formed under semi-arid conditions, show maturity under stable deposition. They suggest a felsic, recycled source, with moderate alteration and zircon enrichment during recycling. In the study area, limestones and dolomites serve as materials applicable in the building sector, suitable for all types of concrete. The Taliwine Formation harbors Lower Cambrian dolomites and limestones, ideal for mosaic aggregates. Described as variable in color, compact, homogeneous, very hard, and resistant to alteration, the plutonic rocks form prominent peaks. They exhibit both subalkaline characteristics in granitoids and an alkaline trend in dolerite dykes. Most samples display minimal alteration, indicating the reliability of their major element compositions for geochemical analyses. These granitoids constitute valuable deposits for ornamental and building rock purposes.

An ecotourism suitability index for a world heritage city using GIS-multi criteria decision analysis techniques.

The concept of ecotourism has experienced a significant surge in popularity over the past two decades, primarily driven by the multitude of adverse impacts associated with mass tourism. The objective of the study was to develop a comprehensive ecotourism suitability index to guide policymakers in implementing tourism development policies. Given the considerable appeal of the study area to both local and international tourists, it is essential to conduct a systematic evaluation to pinpoint suitable areas for ecotourism development. This necessity arises from the study area's placement within a fragile ecosystem and its proximity to a UNESCO World Heritage site. We employed a Geographic Information Systems (GIS) integrated environment coupled with a fuzzy Multi-Criteria Decision Analysis (MCDA) methodology. The GIS-MCDA integrated framework leverages the Analytic Hierarchy Process (AHP) and a weighted linear combination that seeks to amalgamate many features and criteria to assess ecotourism potential by integrating 20 criteria into six separate categories: landscape, topography, accessibility, climate, forest and wildlife, and negative factors. Weights were allocated to each criterion and factor based on the expert's opinions of their impact on the development of ecotourism. The final ecotourism suitability index comprised five unique classes: very high, high, moderate, less, and not suitable. Results reveal that out of the total areas, 45.4 % (259 km2) are within the high and very high suitable classes. The sensitivity analysis suggested that ecotourism potentials are more favorable to forest and accessibility variables. The generated index can be utilized as a road map since validation verified a 64 % accuracy. Given the dearth of earlier research, this study provides vital support for the development of sustainable ecotourism projects in the study area.

Geochemical Evaluation of Paleocene Source Rocks in the Kohat Sub-Basin, Pakistan.

The Kohat sub-basin is one of the main hydrocarbon-producing sedimentary basins located in the northwest extension of the Indus Basin in Pakistan. It contains numerous proven and potential petroleum from the Cambrian to the Miocene. Conventional petroleum resources have been depleting rapidly over the last couple of years. Therefore, unconventional resources should be explored using a variety of geochemical and geophysical techniques to address the energy demands. Geochemical techniques, including total organic carbon (TOC) assessment, Rock-Eval pyrolysis, organic petrography, and biomarker studies, are essential for evaluating the potential of shale gas reservoirs to delineate future prospects in a basin. The source rock potential of the Paleocene rocks, including the Patala, Lockhart, and Hangu formations of the sub-basin, is evaluated using geochemical analyses on well cuttings from the Tolanj-01 well. The analyses include estimation of total organic carbon (TOC), Rock-Eval pyrolysis, and organic petrography (vitrinite reflectance) to evaluate the organic richness, thermal maturity, kerogen type, hydrocarbon type, and environment of deposition. Other techniques for extractable organic matter (EOM) include solid-liquid chromatographic separation of fractions, gas chromatography (GC-FID)/whole oil chromatography, and gas chromatography-mass spectrometry (GC-MS). The organic matter (TOC, wt %) analysis reveals that 18 (18) samples of the Hangu formation (0.08-1.8 wt %) show poor values, 12 (12) samples of the Lockhart formation (0.05-0.5 wt %) have poor to fair content, and 26 (26) samples of the Patala formation have poor to fair (0.08-0.19 wt %) TOC content. Rock-Eval pyrolysis studies including hydrogen index, oxygen index, Tmax, quantities of free hydrocarbons (S1, mg/g), and hydrocarbons produced from pyrolysis (S2, mg/g) are determined for the well-cut samples (56) of the Paleocene rocks. The hydrogen index values for the Hangu formation are lower than 200, and those for the Lockhart and Patala formations range between 100 and 250. A maceral analysis is also conducted on these samples, which reveal that the majority of the samples of the Paleocene units present in the basin belong to kerogen types II/III. The thermal maturity of the Hangu and Lockhart formations falls in the late-stage oil window, while that of the Patala formation falls in the peak to late oil window. The genetic potential (GP) for these rock units is also determined based on S1 and S2 values, which reveals that it is generally poor except for a few samples of the Hangu and Lockhart formations, which show fair GP values. For the organic petrography (vitrinite reflectance, R0), one sample from each unit is selected, which shows that the Hangu, Lockhart, and Patala formations fall in the category of the mature oil window with their R0 (%) values being 0.95, 0.89, and 0.82, respectively. The extracts (EOM) from these rock units are also analyzed to assess the depositional settings, biological source input, biodegradation, thermal maturity, etc. The greater values of pristine to phytane (Pr/Ph > 1) ratios for Hangu (1.33), Lockhart (1.23), and Patala (1.8) indicate an intermediate condition (suboxic), while a cross-plot of Pr/n-C17-Ph/n-C18 shows that the organic matter is deposited in a transitional setting. The ratios between C19TCT/C19 TCT + C23 TCT and C24 TeCT/C24TeCT + C23TCT biological source inputs are mainly of marine origin. Similarly, the ternary diagram of regular steranes (C27-C28-C29) shows a greater marine input. Lower values of the carbon preference index (CPI1) for Hangu (0.95), Lockhart (0.91), and Patala (1.04) indicate higher thermal maturity of the Paleocene rocks. Similarly, the methylphenanthrene index (MPI-1) values, Moretane index, and Pr/n-C17 vs Ph/n-C18 plots also show higher thermal maturity for these rock extracts.

Unconventional Reservoir Characterization of Patala Formation, Upper Indus Basin, Pakistan.

Unconventional hydrocarbon exploration is needed in the current oil and gas crisis scenario. Therefore, the development of conditions for unconventional hydrocarbon exploration is needed. In the Upper Indus Basin (UIB), Pakistan, the Patala Formation is one of the potential candidates for this unconventional exploration. It is a proven source rock at the regional level in the Kohat-Potwar sub-basin of UIB. This study aims to evaluate the shale gas potential of the rock in the Minwal-Joyamair area of the sub-basin. Developing a shale rock physics model is important for exploring and developing shale reservoirs due to the difference between unconventional shale and conventional sand reservoirs. These differences include mineral types, mineral characteristics, matrix pores, and fluid properties. To achieve the study's objectives, an integrated strategy provides for evaluating rock physics parameters, petrophysics, and geochemical analyses. This integrated approach indicates that the Patala Formation is a good potential reservoir for shale gas exploration. The Formation has a significant thickness (around 40-50 m), higher total organic carbon content (02-10%), higher brittleness index (0.44-0.56), and relatively shallow depth (2136-3223 m). These research findings suggested that the presence of organic and quartz-rich lithofacies can be considered as highly favorable "sweet spots" for shale-gas exploration in the UIB, Pakistan. Through proper understanding of the spatial and temporal distribution of these "sweet spots", shale-gas exploration can be developed as an effective strategy to exploit shale gas.

Reliable Tilt-depth estimates based on the stable computation of the tilt angle using robust vertical derivatives.

The Tilt-depth is a popular approach for determining depths of magnetic sources. As this method is based on the distance between contour levels of the tilt angle, it can lead to inaccurate depth estimates when the contour lines are distorted by the presence of noise. In this paper, we stabilize the Tilt-depth method based on the computation of stable vertical derivative obtained by the ß-VDR method. The presented method is demonstrated on synthetic magnetic anomalies and real magnetic data from the Arabian Shield. The results obtained from the synthetic examples coincide well with the actual depths. These results proved the utility of the presented method in cases where the field is corrupted by noise. The real example shows that the presented method can provide valuable information on subsurface structures of the area where the Tilt-depth estimates are consistent with the result of the horizontal tilt angle. The findings show that the presented method is less sensitive to noise and can provide source edges and depths more clearly and with higher accuracy.

Predicting sediment yield on different landuse surfaces in Calabar River Catchment, Nigeria.

This study predicts sediment yield on various landuse surfaces within the Calabar River Catchment, Nigeria. Five experimental plots of 31 by 23 cm (representing urban, farm, grass, bare, and forest surfaces) were established on a convex slope series with a 20% gradient, oriented along the slope strike. Rainfall, morphological, and hydraulic stations were derived for each plot. Multiple regressions and Factor analysis were employed to analyse the collected data. The research identifies critical factors influencing sediment yield, such as rainfall amount, rainfall intensity, slope gradient, slope length, sand, silt, clay, vegetation cover, and infiltration capacity. The results (p < 0.05) indicate that slope length, sand, silt, clay, infiltration capacity, and vegetation cover significantly influence sediment yield for urban, farmland, grassland, and bare surfaces, respectively. Factor analysis revealed strong correlations between sediment yield, silt, rainfall amount, rainfall intensity, and slope gradient. Case-wise diagnostics predictions indicate sediment yields for urban, bare, farm, grass, and vegetation-covered surfaces as 14.95 kg, 33.91 kg, 28.78 kg, 33.50 kg, and 5.66 kg, respectively. The regression model, with case-wise diagnostic residual statistics and standard prediction coefficients, provides valuable insights. For example, the forest surface exhibited a minimum sediment yield of -1.413 kg/m2 with each unit decrease in forest area, emphasising the significance of vegetation cover in sediment retention. Conversely, bare surfaces showed a maximum sediment yield of 0.843 kg/m2 with each unit increase in bare surface area, highlighting their heightened vulnerability to sediment erosion. Considering the implications of these findings, the development of urban master plans that incorporate well-designed landscaping and drainage systems is crucial, particularly in high rainfall catchments like the study area. Such measures can effectively mitigate sediment yield and address the adverse effects of land use changes on different surfaces.