The thermal maturity of sedimentary basins as revealed by magnetic mineralogy     

Mansour M. Abdelmalak  Stéphane Polteau 《Basin Research》2020,32(6):1510-1531

The thermal evolution of sedimentary basins is usually constrained by maturity data, which is interpreted from Rock-Eval pyrolysis and vitrinite reflectance analytical results on field or boreholes samples. However, some thermal evolution models may be inaccurate due to the use of elevated maturities measured in samples collected within an undetected metamorphic contact aureole surrounding a magmatic intrusion. In this context, we investigate the maturity and magnetic mineralogy of 16 claystone samples from Disko-Svartenhuk Basin, part of the SE Baffin Bay volcanic margin. Samples were collected within thermal contact metamorphic aureoles near magma intrusions, as well as equivalent reference samples not affected by intrusions. Rock-Eval pyrolysis (T_max), and vitrinite reflectance (Ro) analysis were performed to assess the thermal maturity, which lies in the oil window when 435°C ≤ T_max ≤ 470°C and 0.6%–0.7% ≤ Ro ≤ 1.3%. In addition, we performed low- (<300K) and high-temperature (>300K) investigations of isothermal remanent magnetization to assess the magnetic mineralogy of the selected samples. The maturity results (0.37% ≤ Ro ≤ 2%, 22°C ≤ T_max ≤ 604°C) show a predominance of immature to early mature Type III organic matter, but do not reliably identify the contact aureole when compared to the reference samples. The magnetic assemblage of the immature samples consists of iron sulphide (greigite), goethite and oxidized or non-stoichiometric magnetite. The magnetic assemblage of the early mature to mature samples consists of stoichiometric magnetite and fine-grained pyrrhotite (<1 μm). These results document the disappearance of the iron sulphide (greigite) and increase in content of magnetite during normal burial. On the other hand, magnetite is interpreted to be the dominant magnetic mineral inside the contact aureole surrounding dyke/sill intrusions where palaeotemperatures indicate mature to over-mature state. Interestingly, the iron sulphide (greigite) is still detected in the contact aureole where palaeotemperatures exceeded 130°C. Therefore, the magnetic mineralogy is a sensitive method that can characterize normal burial history, as well as identify hidden metamorphic contact aureoles where the iron sulphide greigite is present at temperatures beyond its stability field.  相似文献   

Impact of model complexity and multi-scale data integration on the estimation of hydrogeological parameters in a dual-porosity aquifer     

Elena Tamayo-Mas  Marco Bianchi  Majdi Mansour 《Hydrogeology Journal》2018,26(6):1917-1933

This study investigates the impact of model complexity and multi-scale prior hydrogeological data on the interpretation of pumping test data in a dual-porosity aquifer (the Chalk aquifer in England, UK). In order to characterize the hydrogeological properties, different approaches ranging from a traditional analytical solution (Theis approach) to more sophisticated numerical models with automatically calibrated input parameters are applied. Comparisons of results from the different approaches show that neither traditional analytical solutions nor a numerical model assuming a homogenous and isotropic aquifer can adequately explain the observed drawdowns. A better reproduction of the observed drawdowns in all seven monitoring locations is instead achieved when medium and local-scale prior information about the vertical hydraulic conductivity (K) distribution is used to constrain the model calibration process. In particular, the integration of medium-scale vertical K variations based on flowmeter measurements lead to an improvement in the goodness-of-fit of the simulated drawdowns of about 30%. Further improvements (up to 70%) were observed when a simple upscaling approach was used to integrate small-scale K data to constrain the automatic calibration process of the numerical model. Although the analysis focuses on a specific case study, these results provide insights about the representativeness of the estimates of hydrogeological properties based on different interpretations of pumping test data, and promote the integration of multi-scale data for the characterization of heterogeneous aquifers in complex hydrogeological settings.  相似文献   

Structural Setting and Kinematic Analysis of the Halaban Region,Eastern Arabian Shield,Saudi Arabia     

Osama M. KASSEM  Yousef A. ALAMRI  Faisal K. ZAIDI  Abdel Aziz M. AL BASSAM  Mansour H. AL-HASHIM 《《地质学报》英文版》2021,95(3):750-760

The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret the relationship between the different lithologies and the tectonic setting,in order to elucidate the nature of kinematic analysis in the Halaban region.The kinematic analyses were applied to feldspar porphyroclasts,quartz and hornblende for twentysix samples.The kinematic vorticity number (W_m) for deformed rocks in the study area ranged from～0.6 to 0.9.The direction of the long axes for finite strain data (X axes) revealed a WNW trend with shallow dipping.The direction of the short axes for finite strain data (Z axes) were represented by vertical with associated horizontal foliation.The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region.Furthermore,our finite strain data shows no significant volume change during deformation.The subhorizontal foliation was synchronized with thrusting and deformation.Furthermore,throughout the overlying nappes,the same attitudes of tectonic contacts are observable,the nappes in the orogens being formed from simple shear deformation.  相似文献   

Magnetic and DC resistivity investigation for groundwater in a complex subsurface terrain     

Mansour A. Al-Garni 《Arabian Journal of Geosciences》2011,4(3-4):385-400

Subsurface structures associated with hard rocks are very important for groundwater. Wadi Fatima runs through the volcanic and metamorphic rocks of the Arabian Shield which are characterized by higher magnetization than the overlaying alluvium sediments. Magnetic and direct current (DC) resistivity methods have been used for groundwater exploration in the northern part of Wadi Fatima. The magnetic survey was used mainly to map the subsurface structures, using analytic signal algorithm, of the study area. The DC resistivity method was applied to describe the lithologic domain as a function of depth, depending on their electrical property contrasts where it provided a good indication for water bearing formations. The magnetic and DC resistivity interpretations were confirmed by drilling which have provided a clear idea about the hydrogeological regime of the study area. The selected drilled well is successfully productive and it produces 30 m³/h.  相似文献   

On the rise of strongly tilted mantle plume tails     

C.A. Mériaux  J.A. Mansour  L.N. Moresi  R.C. Kerr  D.A. May 《Physics of the Earth and Planetary Interiors》2011,184(1-2):63-79

The rise of an initially horizontal, buoyant cylinder of fluid through a denser fluid at low Reynolds number is used to look at the ascent of strongly tilted mantle plumes through the mantle. Such ascents are characterized by (1) the growth of instabilities and (2) the development of a thermal wake downstream. Three-dimensional numerical experiments were carried out to examine these features. An hybrid particle-in-cell finite element method was used to look at the rise of non-diffusing cylinders and, a standard finite element method was used to look at the diffusing case. First the experiments show that the timescale of the fastest growing instability vary with the Rayleigh number and the viscosity ratio. In particular the growth rate decreases as the Rayleigh number decreases, in agreement with our analysis of the laboratory experiments of Kerr et al. (2008). Second the experiments show that the length of the thermal wake increases with the Rayleigh number but the change in viscosity has almost no influence on the wake length. Applied to strongly tilted mantle plumes we conclude that such plumes cannot be unstable given the plume timescales. We also discuss the application of this conclusion to weakly tilted plumes. Besides, this study allows to predict that mantle plumes are unlikely to have developed a significant thermal wake by the time they reach the surface. Finally, the resolution that is required to allow for the growth of mantle plume tails by combined diffusion and thermal entrainment is shown to represent a challenge for the large scale mantle convection simulations.  相似文献   

Urbanization effects on the air temperature rise in Saudi Arabia     

Mansour Almazroui  M. Nazrul Islam  P. D. Jones 《Climatic change》2013,120(1-2):109-122

We study the possible effects of urbanization on the rise of air temperature in Saudi Arabia for the period 1981–2010. The effects of variations in elevation and marine temperature on the air temperature trend are also investigated. Surface air temperature data are analyzed for 24 sites which are mostly located at the airports across the country. The population data for the current (2010) and earlier (2004 and 1992) censuses are used for the nearest cities where the observation sites are located. A national average is calculated using two different approaches (simple averaging and weighted according to area for 1985–2010 when all stations are available) which gives trends of 0.60 and 0.51 °C/decade respectively, both significant at the 99 % level. We find no link between the temperature increase and population increase nor with elevation at the 24 sites which are mostly located in the urban effected area but not at the city centers. This suggests that the rise in air temperature is not likely due to urbanization changes resulting from the population increases.  相似文献   

Attapulgite as Potential Adsorbent for Dissolved Organic Carbon From Oily Water          下载免费PDF全文

Mansour Al. Haddabi  Hari Vuthaluru  Hussein Znad  Mushtaque Ahmed 《洁净——土壤、空气、水》2015,43(11):1522-1530

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Application of a 3D photorealistic model for the geological analysis of the Permian carbonates (Khuff Formation) in Saudi Arabia     

Mansour S. Alhumimidi  Mohammed S. Alfarhan  Jarvis R. Cline  Carlos L. V. Aiken 《Arabian Journal of Geosciences》2017,10(5):112

Three dimensional (3D) photorealistic models of geological outcrops have the potential to enhance the teaching of earth sciences by providing scale models in a virtual reality environment. These models can be run on low-cost desktop computers. Photorealistic models for geological outcrops are a digital illustration of outcrop photographs with either a point cloud representation or Triangular Irregular Network (TIN) mesh of the outcrop surface. The level of detail for these models is dependent on the target resolutions (physical and optical) that were used during data acquisition. In addition, the technique in which the data is rendered as a digital model affects the level of detail that can be observed by the geologists. A colored point cloud representation is suitable for large-scale features, but fine details are lost when the geologist zooms in to view the model close up. In contrast, a photorealistic model that is constructed from photographs draped onto a triangle mesh surface derived from Light Detection and Ranging (LiDAR) point clouds provides a level of detail that is restricted only by the resolution of the photographs.  相似文献   

Direct CPT and CPTu methods for determining bearing capacity of helical piles     

Amir Mansour Askari Fateh  Ahmad Fahimifar 《Marine Georesources & Geotechnology》2017,35(2):193-207

Helical piles are structural deep foundation elements, which can be categorized as torque-driven piles without any limitations to implement in marine situations. Different methods are used to predict the axial capacity of helical piles, such as static analysis, but have some limitation for this type of piles on marine conditions. In situ testing methods as supplement of static analysis have been rarely used for helical piles. In geotechnical engineering practice, the most common in situ tests particularly applicable for coastal or offshore site investigation are cone penetration test (CPT) and piezocone penetration test (CPTu). The CPT is simple, repeatable, and prepares the continuous records of soil layers. In this paper, a data bank has been compiled by collecting the results of static pile load tests on thirty-seven helical piles in ten different sites including CPT or CPTu data. Axial capacities of thirty-seven helical piles in different sites were predicted by direct CPT methods and static analysis. Accuracy estimation of ten direct CPT methods to predict the axial capacity of helical piles was investigated in this study. Comparisons have been made among predicted values and measured capacity from the pile load tests. Results indicated that the recently developed methods such as NGI-05 (2005), ICP-05 (2005), and UWA-05 (2005) predicted axial capacity of helical piles more accurately than the other methods such as Meyerhof (1983), Schmertmann (1978), Dutch (1979), LCPC (1982), or Unicone (1997). However, more investigations are required to establish better correlation between CPT data and axial capacity of helical piles.  相似文献   

PROMETHEE II and fuzzy AHP: an enhanced GIS-based landslide susceptibility mapping   总被引：2，自引：0，他引：2  

Majid Shadman Roodposhti  Saeed Rahimi  Mansour Jafar Beglou 《Natural Hazards》2014,73(1):77-95

This paper describes the application of a well-known multi-criteria decision-making technique, called preference ranking organization method for enrichment evaluation (PROMETHEE II), in combination with fuzzy analytical hierarchy process (FAHP), as a weighting technique to explore landslide susceptibility mapping (LSM). To this end, eight landslide-related geodata layers of the Minoo Dasht located in the Gorgan province of Iran, involving slope, aspect, distance to river, drainage density, distance to fault, mean annual rainfall, distance to road and lithology have been integrated using the PROMETHEE II enhanced by FAHP technique. Afterward, the receiver operating characteristics (ROC) curves for the proposed LSM were drawn using an inventory of landslides containing 83 recent and historic landslide points, and the area under curve = 0.752 value was calculated accordingly. Additionally, to further verify the practicality of such susceptibility map, it was also evaluated against the landslide inventory using simple overlay. The outcome was that about 11 % of the occurred landslide points fall into the very high susceptibility class of the LSM, but approximately 52 % of them indeed fall into the high and very high susceptibility zones together. Also, it resulted that no recorded landslide occurred in the zone of very low susceptibility. According to the results of the ROC curves analysis and simple overlay evaluation, the produced map has exhibited good performance.  相似文献