印度板块和亚洲大陆在何时何地碰撞

印度板块和亚洲大陆的初始碰撞时间是所有相关的喜马拉雅-西藏造山体系演化模式的主控条件,并严重影响到对众多与青藏高原隆升和东亚大陆挤出相关的地质过程速率的解释,以及对新生代全球气候变化的理解。尽管印度板块和亚洲大陆汇聚的速率在55Ma突然减缓被广泛地认为是初始碰撞的标志,但这次碰撞所造成的主要构造效应直到20多个百万年以后才显现出来。对印度板块和亚洲大陆相对位置的重新估算,表明它们在55Ma时并没有达到可以彼此发生碰撞的距离。基于来自西藏新的野外证据和对已有数据的重新评估,认为初始碰撞发生在始新世—渐新世之交（约34Ma）,并对55Ma时发生的地质事件提出了另一种解释     

Prediction of Rock Abrasivity Index (RAI) and Uniaxial Compressive Strength (UCS) of Granite Building Stones Using Nondestructive Tests

Geotechnical and Geological Engineering - Rock abrasivity index (RAI) and uniaxial compressive strength (UCS) are two key parameters for assessing abrasivity and durability of building stones,...     

A 2-year study of soil tillage and cattle manure application effects on soil fauna populations under Zea Mays cultivation, in western Iran (Sanandaj)

The absence of environmentally sensitive soil management systems can be considered as one of the major risks to sustainability of agricultural soils in Iran. Tillage is the most critical operation in soil management designed to achieve high crop yield, but it can adversely affect the soil fauna in several ways. In the present study, assessment of soil fauna was carried out in Western Iran in 2008 and 2009 in soil subjected to conventional (CT), minimum (MT) and no (NT)-tillage systems and amended with three levels of cattle manure (CM). Earthworm, mite, springtail and nematode populations were measured as indicators of macro, meso and micro fauna groups, respectively. Soil moisture and bulk density were also determined. Generally, low populations of soil fauna were observed consistent with expectations under similar conditions for this region. Earthworm populations were low and had a patchy distribution. Tillage and CM were found to have no effects on soil mites in both years. Soil springtails were reduced by soil tillage, indicating their sensivity to soil disturbance induced by tillage. In 2008, the nematode population was greater with application of 40 ton ha^?1 CM applications (113 N.100 g soil^?1). Soil tillage-induced disturbance reduced nematode population in 2009 (214 N.100 g soil^?1 at CT). Minimum seedbed preparation besides less soil disturbance makes MT a proper tillage system for Zea mays cultivation. Cattle manure application increased Z. mays’ biomass, but according to our results its annual application is not recommended. There were no changes in BD in both years. We conclude that in short-term studies, soil nematode populations are suitable biological indices (under similar soil and climatic conditions) for the ecological comparison of agricultural management systems in Iran.     

Development of a Darcy-Brinkman model to simulate water flow and tracer transport in a heterogeneous karstic aquifer (Val d’Orléans, France)

Darcy’s law is the equation of reference widely used to model aquifer flows. However, its use to model karstic aquifers functioning with large pores is problematic. The physics occurring within the karstic conduits requires the use of a more representative macroscopic equation. A hydrodynamic model is presented which is adapted to the karstic aquifer of the Val d’Orléans (France) using two flow equations: (1) Darcy’s law, used to describe water flow within the massive limestone, and (2) the Brinkman equation, used to model water flow within the conduits. The flow equations coupled with the transport equation allow the prediction of the karst transfer properties. The model was tested by using six dye tracer tests and compared to a model that uses Darcy’s law to describe the flow in karstic conduits. The simulations show that the conduit permeability ranges from 5?×?10^?6 to 5.5?×?10^?5?m² and the limestone permeability ranges from 8?×?10^?11 to 6?×?10^?10?m². The dispersivity coefficient ranges from 23 to 53 m in the conduits and from 1 to 5 m in the limestone. The results of the simulations carried out using Darcy’s law in the conduits show that the dispersion towards the fractures is underestimated.     

Synsedimentary deformations in member 2 of the Mila Formation in the Central Alborz Mountains,Northern Iran

In Alborz Mountains, the thickness of sediments in Member 2 of the Mila Formation (Middle Cambrian) underwent dramatic and abrupt deformations, which were accompanied by normal and reverse faults and asymmetrical folds. These deformed sediments are covered by parallel beds both in the upper and lower sides. The existence of such extension and compression structures adjacent to each other indicates the influence of non-tectonic factors in their evolution. These deformations induced by downslope gliding of sediment packages are fully compatible with the dislocation model of Farrell (J Struct Geol 6:727–736, 1984) and Farrell and Eaton (1987). Moreover, the occurrence of synsedimentary deformations in a vast area in Alborz Mountains reinforces the probability of the impact of seismic shocks in their formation. In fact, incessant seismic events in the Middle Cambrian led to numerous submarine slumpings in the sediments of Member 2 of the Mila Formation.     

Interfacial instability of sand patterns induced by turbulent shear flow

When a turbulent shear flow above a plane sand surface entrains sand grains,it generates a variety of sand patterns.Fluvial sand forms two major interfacial patterns:meso-scale dunes and antidunes,and large-scale bars.Measurements have evidenced that under erosive conditions,meso-scale patterns either change to or coexist with large-scale patterns.However,it remains elusive what exactly drives the switching of interfacial patterns and how the switching occurs.Here,we showdcombing a flow model with a grain transport model,allowing for both the surface and suspended sand fluxes dthat the switching of patterns emerges from the shear-driven complex feedback between grain transport and topographic perturbations.The switching predominantly depends on the magnitudes of the Rouse number and the grain size to undisturbed flow depth ratio.The model offers quantitative predictions of the maximum amplification of sand patterns and unveils a new attraction erepulsion phenomenon.     

Optimization of a Photo‐assisted Fenton Oxidation Process: A Statistical Model for MDF Effluent Treatment

In the present study, the effects of initial COD (chemical oxygen demand), initial pH, Fe²⁺/H₂O₂ molar ratio and UV contact time on COD removal from medium density fiberboard (MDF) wastewater using photo‐assisted Fenton oxidation treatment were investigated. In order to optimize the removal efficiency, batch operations were carried out. The influence of the aforementioned parameters on COD removal efficiency was studied using response surface methodology (RSM). The optimal conditions for maximum COD removal efficiency from MDF wastewater under experimental conditions were obtained at initial COD of 4000 mg/L, Fe²⁺/H₂O₂ molar ratio of 0.11, initial solution pH of 6.5 and UV contact time of 70 min. The obtained results for maximum COD removal efficiency of 96% revealed that photo‐assisted Fenton oxidation is very effective for treating MDF wastewater.     

Exploring Real‐Time Geoprocessing in Cloud Computing: Navigation Services Case Study

Today, many real‐time geospatial applications (e.g. navigation and location‐based services) involve data‐ and/or compute‐intensive geoprocessing tasks where performance is of great importance. Cloud computing, a promising platform with a large pool of storage and computing resources, could be a practical solution for hosting vast amounts of data and for real‐time processing. In this article, we explored the feasibility of using Google App Engine (GAE), the cloud computing technology by Google, for a module in navigation services, called Integrated GNSS (iGNSS) QoS prediction. The objective of this module is to predict quality of iGNSS positioning solutions for prospective routes in advance. iGNSS QoS prediction involves the real‐time computation of large Triangulated Irregular Networks (TINs) generated from LiDAR data. We experimented with the Google App Engine (GAE) and stored a large TIN for two geoprocessing operations (proximity and bounding box) required for iGNSS QoS prediction. The experimental results revealed that while cloud computing can potentially be used for development and deployment of data‐ and/or compute‐intensive geospatial applications, current cloud platforms require improvements and special tools for handling real‐time geoprocessing, such as iGNSS QoS prediction, efficiently. The article also provides a set of general guidelines for future development of real‐time geoprocessing in clouds.     

The depositional environment of Mauddud limestone,Greater Burgan oil field,Kuwait

Six microfacies are defined on quantitative petrographic data in a carbonate/clastic sequence from the subsurface, oil producing Mauddud Formation of early Middle Cretaceous age. These are, in descending order of importance and abundance: (1) biomicritic wackestone-packstone, (2) argillaceous mudstone, (3) micritic mudstone, (4) glauconitic sandstone, (5)Orhitolina pelsparitic grainstone, and (6) argillaceous dolomite.Sedimentation took place during a marine transgression onto a very shallow, intertidal, restricted marine shelf lagoons. Facies variations appear to be related to depth and energy changes and proximity to areas of clastic deposition. These changes may have been controlled by slight tectonic events in the hinterland and changes in the rate of basin subsidence.

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Zusammenfassung Auf der Grundlage quantitativer petrographischer Daten werden sechs Mikrofazies in einer karbonat/klastischen Folge aus der unter der ErdoberflÄche liegenden, ölliefernden Mauddud-Formation der frühen Mittelkreide definiert. In absteigender Reihenfolge der Bedeutung und HÄufigkeit sind dieses: (1) biomikritischer wackestone-packstone, (2) toniger Schlickstein, (3) unkritischer Schlickstein, (4) glaukonitischer Sandstein, (5) Orbitolina-führender pelsparitischer Grainstone und (6) toniger Dolomit.Die Sedimentation erfolgte wÄhrend einer marinen Transgression auf sehr flache, intertidale Lagunen eines begrenzten marinen Schelfs. Die Fazies-Variationen scheinen mit den Wechseln in Wassertiefe und Energie sowie der mit NÄhe von Gebieten mit klastischer Sedimentation zusammenzuhÄngen.Diese Wechsel könnten durch kleinere tektonische Ereignisse im Hinterland und durch VerÄnderungen der Absenkungsrate des Beckens ausgelöst worden sein.

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Résumé Des données pétrographiques quantitatives permettent de définir six microfacies dans une série clasto-carbonatée d'âge crétacé inférieur du sous-sol de la région pé trolifère de Mauddud. Ce sont par ordre décroissant d'importance et d'abondance: (1) des wacstones-pacstone biomicritiques; (2) des argilites; (3) des argilites micritiques; (4) des grès glauconitiques; (5) des grainstone pelsparitiques à orbitolines; (6) des dolomies argileuses.La sédimentation se produisit au cours d'une transgression marine dans des lagunes très plates, intercotidales, d'une plate-forme continentale de faible étendue. Les variations de facies semblent Être dues à des changements de profondeur et d'énergie, ainsi qu'à la proximité de régions à sédimentation clastique.Ces changements pourraient résulter de légers mouvements tectoniques dans l'arrière-pays et de variations dans le degré de subsidence du bassin de sédimentation.

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