3-D seismic structure of Kii Peninsula in southwest Japan: evidence for slab dehydration in the forearc   总被引：1，自引：0，他引：1  

Mohamed K. Salah  Dapeng Zhao 《Tectonophysics》2003,364(3-4):191-213

Kii Peninsula is located in the forearc region of southwest Japan and has distinct structural and tectonic features characterized by high seismicity in the crust and the subducting Philippine Sea slab, high surface heat flow, high ³He/⁴He isotopic ratio, and a local change in the geometry of the subducting slab. We have tried to determine detailed 3-D P and S wave velocity structures of this region using a large number of high-quality arrival time data recorded by dense seismic networks on the Japan Islands. From the obtained seismic velocities, we further estimated 3-D distributions of Poisson ratio, crack density, saturation rate and porosity parameter in the study area. Our results show significant heterogeneities in the crust and upper mantle wedge characterized by low seismic velocities, high Poisson ratio, high values of crack density, saturation rate and porosity. These results suggest the existence of fluids in the crust and mantle wedge resulting from the dehydration of the subducting Philippine Sea slab, which can explain the observed geophysical and geochemical features in Kii Peninsula.  相似文献   

Imaging of V_p, V_s, and Poisson’s ratio anomalies beneath Kyushu, southwest Japan: Implications for volcanism and forearc mantle wedge serpentinization     

Mohamed K. Salah  Tetsuzo Seno 《Journal of Asian Earth Sciences》2008,31(4-6):404-428

We determine detailed 3-D V_p and V_s structures of the crust and uppermost mantle beneath the Kyushu Island, southwest Japan, using a large number of arrival times from local earthquakes. From the obtained V_p and V_s models, we further calculate Poisson’s ratio images beneath the study area. By using this large data set, we successfully image the 3-D seismic velocity and Poisson’s ratio structures beneath Kyushu down to a depth of 150 km with a more reliable spatial resolution than previous studies. Our results show very clear low V_p and low V_s anomalies in the crust and uppermost mantle beneath the northern volcanoes, such as Abu, Kujyu and Unzen. Low-velocity anomalies are seen in the mantle beneath most other volcanoes. In contrast, there are no significant low-velocity anomalies in the crust or in the upper mantle between Aso and Kirishima. The subducting Philippine Sea slab is imaged generally as a high-velocity anomaly down to a depth of 150 km with some patches of normal to low seismic wave velocities. The Poisson’s ratio is almost normal beneath most volcanoes. The crustal seismicity is distributed in both the high- and low-velocity zones, but most distinctly in the low Poisson’s ratio zone. A high Poisson’s ratio region is found in the forearc crustal wedge above the slab in the junction area with Shikoku and Honshu; this high Poisson’s ratio could be caused by fluid-filled cracks induced by dehydration from the Philippine Sea slab. The Poisson’s ratio is normal to low in the forearc mantle in middle-south Kyushu. This is consistent with the absence of low-frequency tremors, and may indicate that dehydration from the subducting crust is not vigorous in this region.  相似文献   

陶瓷工业中对产白花岗岩的长石原料的提纯方法研究     

Mohamed El-Omla Salah Shata 《地质与资源》2008,17(3)

花岗岩是陶瓷工业中所需长石原料的重要来源之一．由于花岗岩中云母和氧化铁的存在,其最终产品的质量受到影响（强度、硬度、密度降低）．本研究对浙江花岗岩采用两阶段分离方法,以提高花岗岩中长石的质量．第一阶段为重力分离,去除重矿物杂质;第二阶段为磁性分离,进一步减少铁含量．用机械方法对不同加工阶段的3种样品进行了成分测试：1）原料花岗岩;2）第一阶段处理的花岗岩;3）第二阶段处理的花岗岩．结果显示,最终处理后的样品较之原始花岗岩在显微硬度、强度、密度及裂隙坚韧性方面都有明显提高．  相似文献   

Geologic problems related to dam sites in Jordan and their solutions   总被引：1，自引：0，他引：1  

Azm S. Al-Homoud  Salah A. Taqieddin  Fadhil H. Ahmad 《Engineering Geology》1995,39(3-4):233-263

The geologic structures associated with several selected dam sites in Jordan and the tectonic effects on dam foundations and reservoir margins are reviewed. Rock defects, especially discontinuities represented by faults and closely spaced, open joints are investigated. Related problems, such as loss of water from the reservoir by seepage and leakage within the dam foundation are evaluated. The regional seismicity is analyzed and a design earthquake is established for each dam site.

Two major embankment dams are investigated, together with two large proposed dams and several small dams.

This paper discusses in some detail the regional setting and site-specific geology, and the occurrence, size and inclination of faults and joints at each dam site. Moreover, the effects of the faults on the operational performance of each dam are described and specific techniques are used or proposed for remediation are outlined.

The study shows that the combination of faults and joint features cause leakage problems at the operational dams in Jordan. Although, preventive measures such as grouting have been implemented, further leakage and/or seepage problems are anticipated and a monitoring system is needed to control and foresee such problems.

Jordan is an earthquake-prone region. Consequently, it is recommended that the design of embankment dams in the vicinity of the Dead Sea-Jordan Valley Rift should include such considerations as dynamic loading and associated hazards, including embankment acceleration zoning, foundation liquefaction risk and rockhead rupture. The magnitude of the design earthquake at each dam site can be estimated following the guidelines of ICOLD (1989), which are based on probabilistic seismic hazard analysis.  相似文献   

Dynamic Response of Pile Reinforced Soils and Piled Foundations     

Salah Messioud  Umur Salih Okyay  Badreddine Sbartai  Daniel Dias 《Geotechnical and Geological Engineering》2016,34(3):789-805

The rigid-pile soil-improvement technique aims to increase the bearing capacity of the soil and decrease the settlement of the surface structure. The most remarkable difference of this technique from the deep-foundation system is the soil layer between the pile heads and the structure. This soil layer, called the mattress, is made of compacted granular materials and participates in the load transfer through arching and shear mechanisms. In order to understand the dynamic behavior of rigid-pile reinforced soils, tri-dimensional finite-element analyses of a soil-pile-slab system, a soil-pile-mattress-slab system, and a soil-pile-mattress-embankment system are presented in this paper. Different geometric configurations are studied in terms of dynamic impedances. The soil, piles, mattress, and embankment are represented as continuum solids, and the slab is represented by structural plate-type elements. The horizontal and vertical impedances of pile foundations are presented and the results are compared with studies in the literature. This study shows the influence of the mattress stiffness, the geometrical configuration, and head/tip fixity conditions on the dynamic response of the foundation system. A comparison between rigid piles and pile foundations is then presented.  相似文献   

Mineralogical and geochemical characterization of listwaenite from the Semail Ophiolite, Oman   总被引：2，自引：0，他引：2  

Sobhi Nasir  Abdul Razak Al Sayigh  Abdulrahman Al Harthy  Salah Al-Khirbash  Omar Al-Jaaidi  Abdullah Musllam  Ali Al-Mishwat  Salim Al-Bu'saidi 《Chemie der Erde / Geochemistry》2007,67(3):213-228

The late Cretaceous-lower Tertiary hydrothermal alteration of serpentinized peridotite in the Semail ophiolite has formed two distinct types of listwaenite. Type I is characterized by the presence of calcite (Type IA) or dolomite (Type IB)+fuchsite±spinel. Type II is dominated by silicate minerals (quartz, chlorite, fuchsite)±calcite+dolomite±magnetite±apatite±plagioclase. Most listwaenites occur as veins along thrust fault zones within the ophiolite mélange. High Cr and Ni contents, abundant occurrence of Cr-spinel within a matrix of red-brown ferruginous carbonates within a micro-vein network of goethite, and the relics of mesh texture indicate an ultramafic protolith. Type I and II listwaenites represent different stages of hydrothermal alteration. The mineralogical and chemical distinctions of both types are the response to the extent of the reactions between the protoliths and the solutions leading to different stages of metasomatic replacement. The hydrothermal fluids involved in the formation of Type I listwaenite were enriched in Ca, Mg, and CO₂, whereas Type II listwaenite bodies were formed from a hydrothermal fluid enriched in SiO₂. REE and trace elements in both listwaenite types were extracted in part from adjoining peridotite. No Au anomaly in the study areas has been detected.  相似文献   

Quantification and Genotyping of Rotavirus A within Two Wastewater Treatment Processes          下载免费PDF全文

Chourouk Ibrahim  Nadia Cherif  Salah Hammami  Pierre Pothier  Abdennaceur Hassen 《洁净——土壤、空气、水》2016,44(4):393-401

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Reliability-based design of spread footings on clays reinforced with aggregate piers     

Ahmad Kahiel  Shadi Najjar  Salah Sadek 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2017,11(1):75-89

ABSTRACT

The economical and safe design of footings supported on aggregate-pier-reinforced clay could benefit from the implementation of a reliability-based approach that incorporates the different sources of uncertainty. Monte Carlo simulations are conducted to quantify the probability distribution of the ultimate bearing capacity for practical design scenarios. A reliability analysis is then conducted to propose design charts that yield the required factor of safety as a function of the major input parameters. The novelty in the proposed methodology is the incorporation of a lower bound shear strength that is based on the remoulded undrained shear strength in the reliability analysis.  相似文献   

Palynological,palynofacies, paleoenvironmental and organic geochemical studies on the Upper Cretaceous succession of the GPTSW-7 well,North Western Desert,Egypt     

Salah Y. El Beialy  Haytham S. El Atfy  Michael S. Zavada  Essam M. El Khoriby  Ramadan H. Abu-Zied 《Marine and Petroleum Geology》2010

The present study of the Abu Roash and Bahariya formations in well GPTSW-7 refines our understanding of the subsurface Cretaceous of the north Western Desert of Egypt. Our investigations are based on the palynological analyses of 71 cuttings samples, of which 24 have also been analyzed for geochemistry, in addition to 3 sidewall cores analyzed for vitrinite reflectance (R_o).  相似文献   

Upper crustal Poisson’s ratio and coda-wave attenuation beneath Eastern Anatolia     

Aydın  Ufuk  Şahin  Şakir  Salah  Mohamed K. 《地震工程与工程振动(英文版)》2020,19(2):335-347

The attenuation of seismic waves reflects the elastic nature of the media within which the waves propagate. In this study, we calculate the Coda-Q(Q_c), frequency dependence(η), Vp/Vs and Poisson's(υ) ratios by using 2621 vertical component seismograms generated by 987 earthquakes recorded by 13 seismic stations in Eastern Anatolia, and creat a 2-D seismic tomographic Q_c model for the region. The obtained model provides significant information for exploring the boundaries of adjacent tectonic units within the upper crust and interpreting their dynamic characteristics. The 2-D Q_c model and the other parameters are consistent with the seismotectonic features of Eastern Anatolia. Highly heterogeneous Q_c values are observed in the study area dividing it into north-south directed bands of low and high attenuation. The highest η values were obtained beneath the northwestern and eastern parts of the study region. Clear, high and low υ values are obtained in the western and eastern parts of the study area, respectively. The spatial variations in the measured parameters are consistent with many geophysical observations including low Pn velocities, efficient Sn blockage, high heat flow, and widespread volcanism. Different upper crustal thicknesses and inhomogeneous stress distribution along the East and North Anatolian Fault Zones may also contribute to the observed heterogeneities.  相似文献