The bituminous mixtures of Tall-e Abu Chizan: A Vth millennium BC settlement in southwestern Iran

Various bituminous artifacts were excavated from the Tall-e Abu Chizan, a late prehistoric (Middle Susiana to Middle Uruk) settlement on the middle of the Curvy plain, between the Karun River and the Ram Hormoz Plain. All samples dated from the Vth millennium BC and cover three periods: 5000–4700 BC (Late Middle Susiana), 4700–4200 BC (Late Susiana 1) and 4200–3900 BC (Late Susiana 2). The bitumens were studied using the techniques of petroleum geochemistry and were compared both to the unaltered crude oils produced from the main oil fields in the area and to the famous Mamatain oil seeps. All samples are very rich in bitumen (average 46 wt%) which has been biodegraded and oxidized. Despite these alteration phenomena, δ¹³C of asphaltenes occur within a narrow range of less than 1‰ PDB. Biodegradation affected the steranes, terpanes, dibenzothiophenes and mono- and triaromatic steroids. Molecular characteristics of terpanes, especially the occurrence of 18α (H)-oleanane, suggest that the bitumen from Tall-e Abu Chizan is a mixture generated from Cretaceous Kazdhumi and Eocene Pabdeh petroleum source rocks. In that respect, bitumens from Tall-e Abu Chizan belong to the same oil family as oil from the Naft Safid field, which is in the vicinity of the archaeological site. In fact, the bitumen at Tall-e Abu Chizan likely originated from oil seepages at Naft Safid. These oil seeps have not yet been sampled or analysed.     

Tectono-sedimentary framework of the Gachsaran Formation in the Zagros foreland basin

Continental collision between Iranian and Arabian plates resulted in the formation of the Zagros fold–thrust belt and its associated foreland basin. During convergence, pre-existing faults in the basement were reactivated and the sedimentary cover was shortened above two different types of basal decollement (viscous/frictional). This led to heterogeneous deformation which segmented not only the Zagros fold–thrust belt but also its foreland basin into different compartments resulting in variation in facies, thickness and age of the sediment infill.Based on this concept, a new tectono-sedimentary model is proposed for one of the most important syn-tectonic sedimentary unit, the Gachsaran salt in the Zagros foreland basin. In this proposed model, it is argued that differential propagation of the deformation front above decollements with different mechanical properties (viscous versus frictional) results in along-strike irregularity of the Zagros deformation front whereas movement along pre-existing basement faults leads to development of barriers across the Zagros basin. The irregularity of the deformation front and the cross-basin barriers divided the Zagros foreland basin into six almost alternating sub-basins where Gachsaran salt and its non-salt equivalents are deposited. In the salt sub-basins, two different processes were responsible for the deposition of Gachsaran salt: (1) evaporation, and (2) dissolution of extruding Hormuz salt and its re-precipitation as Gachsaran salt. Re-precipitation was probably the most significant process responsible for the huge deposit of Gachsaran salt in the extreme south-east part of the Zagros foreland basin.     

Geohazard assessment of sand dunes between Jeddah and Al-Lith, western Saudi Arabia

Serious hazards have taken place in urban areas and road construction in Saudi Arabia because of the presence of accumulations of drifting sand dunes. Several researches, which carried out investigative work to solve this problem, were reviewed. Three locations of dune fields along the area between Jeddah and Al-Lith were investigated. The dune forms was identified. Detailed field investigations showed that barchan dunes are dominant in the area. The sands from the studied locations were found to be similar in grain size and shape parameters. Mineralogically, the sand reflects the composition of the surrounding igneous and metamorphic rocks. Regression analyses were performed and empirical relationships between dune height, width, windward length, slip-face length, and rate of movements were developed. Relatively strong relations exist between these parameters. The most important geometric parameter controlling dune movement with wind speed and direction is determined to be the dune height. A reasonable similarity occurs between the barchan dunes in the study area and those existing in Al Nufud, Al Jafurah sand seas, and Khulays area. The studied dune fields pose some natural hazards on the roads, and the surrounding buildings and constructions in the villages along the area between Jeddah and Al-Lith, especially during wind storms.     

浙江花岗岩中斜长石钾交代产生的条纹长石

对研究区内花岗岩类的60个薄片进行了岩相学研究.研究的目的是确定区内岩石中普遍存在的矿物组成及结构类型.     

Effect of environmental factors on the flora of alluvial fans in southern Sinai

The purpose of this study was to elucidate the floristic and structural characteristics of simple alluvial fan vegetation of southern Sinai and to relate them to environmental variation. The main question addressed was: how does the floristic composition of fan habitats, species richness and life-form vary in relation to environmental change? Thirty-seven alluvial fans, randomly selected in two mainwadis(WadiFeiran andWadiDahab) were analysed quantitively. Two-way Indicator Species Analysis (TWINSPAN) classification and Canonical Correspondence Analysis (CCA) were applied in successive stages of the data analysis to describe vegetational variation in relation to physical gradients. Seven main clusters of fans were defined on the basis of environmental variation. These clusters are divided into three main groups of species richness. Species richness varied along a moisture gradient. The richest fans were the driest habitats, indicating that maximum species richness did not occur at high moisture availability. The moisture gradient is a complex gradient correlated with elevation, slope, climatic aridity, soil texture and the nature of the soil surface. Fine sand, silt plus clay and calcium carbonate showed significant differences between the internal groups and subgroups of the first and second level of the TWINSPAN classification.     

Transient seepage analysis in zoned anisotropic soils based on the scaled boundary finite‐element method

The scaled boundary finite‐element method, a semi‐analytical computational scheme primarily developed for dynamic stiffness of unbounded domains, is applied to the analysis of unsteady seepage flow problems. This method is based on the finite‐element technology and gains the advantages of the boundary element method as well. Only boundary of the domain is discretized, no fundamental solution is required and singularity problems can be modeled rigorously. Anisotropic and non‐homogeneous materials satisfying similarity are modeled with no additional efforts. In this study, firstly, formulation of the method for the transient seepage flow problems is derived followed by its solution procedures. The accuracy, simplicity and applicability of the method are demonstrated via four numerical examples of transient seepage flow – three of them are available in the literature. Homogenous, non‐homogenous, isotropic and anisotropic material properties are considered to show the versatility of the technique. Excellent agreement with the finite‐element method is observed. The method out‐performs the finite‐element method in modeling singularity points. Copyright © 2014 John Wiley & Sons, Ltd.     

An analytical solution for deforming twin‐parallel tunnels in an elastic half plane

The interaction between twin‐parallel tunnels affects the tunnelling‐induced ground deformation, which may endanger the nearby structures. In this paper, an analytical solution is presented for problems in determining displacements and stresses around deforming twin‐parallel tunnels in an elastic half plane, on the basis of complex variable theory. As an example, a uniform radial displacement was assumed as the boundary condition for each of the two tunnels. Special attention was paid to the effects of tunnel depth and spacing between the two tunnels on the surface movement to gain deep insight into the effect of the interaction between twin‐parallel tunnels using the proposed analytical approach. It is revealed that the influence of twin tunnel interaction on surface movements diminishes with both the increase of the tunnel depth and the spacing between the two tunnels. The presented analytical solution manifests that, similar to most of the existing numerical results, the principle of superposition can be applied to determine ground deformation of twin‐parallel tunnels with a certain large depth and spacing; otherwise, the interaction effect between the two tunnels should be taken into account for predicting reliable ground movement. Copyright © 2014 John Wiley & Sons, Ltd.     

Geochemical Prospectivity Mapping Through a Feature Extraction–Selection Classification Scheme

Natural Resources Research - Machine learning (ML) schemes can enhance success in geochemical prospectivity mapping. This study has examined the effectiveness of several feature extraction or...     

An Agent‐Based Simulation of Residential Location Choice of Tenants in Tehran,Iran

Residential location choice modeling is one of the substantial components of land use and transportation models. While numerous aggregated mathematical and statistical approaches have been developed to model the residence choice behavior of households, disaggregated approaches such as the agent‐based modeling have shown interesting capabilities. In this article, a novel agent‐based approach is developed to simulate the residential location choice of tenants in Tehran, the capital of Iran. Tenants are considered as agents who select their desired residential alternatives according to their characteristics and preferences for various criteria such as the rent, accessibility to different services and facilities, environmental pollution, and distance from their workplace and former residence. The choice set of agents is limited to their desired residential alternatives by applying a constrained NSGA‐II algorithm. Then, agents compete with each other to select their final residence among their alternatives. Results of the proposed approach are validated by comparing simulated and actual residences of a sample of tenants. Results show that the proposed approach is able to accurately simulate the residence of 59.3% of tenants at the traffic analysis zone level.