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121.
A football stadium with a capacity of a hundred thousand spectators is under construction over a karst terrain, 10 km west of the old town of Istanbul, Turkey. A large cavity of approximately 30 m3 was detected beneath the sports field through a number of boreholes so that a geophysical survey was required to further investigate a portion of the sports field. We utilized seismic refraction tomography and dc-electrical method with rotated Wenner array to delineate zones with solution voids and cavities. Total core recovery (TCR) was 5–15% from boreholes where zones with low velocities were identified through tomographic inversion, whereas TCR values were above 60% in zones with higher velocities. Both low velocity zones in the tomographic images and increasing resistivity anisotropy with depth appear to indicate that the cavity extends toward the west and south at a depth of approximately 8 m, although the southward and westward extension changes in character. 相似文献
122.
Paleostress analysis of the Cretaceous rocks in the eastern margin of the Dead Sea transform, Jordan
Abdullah A. Diabat Mohammad Atallah Mustafa R. Salih 《Journal of African Earth Sciences》2004,38(5):155
This paper presents the first paleostress results from fault-slip data on Cretaceous limestone at the eastern rim of the Dead Sea transform (DST) in Jordan. Stress inversion of fault-slip data is performed using an improved right dieder method, followed by rotational optimization (Delvaux, TENSOR Program). The orientation of the principal stress axes (σ1, σ2 and σ3) and the ratio of the principal stress differences (
) show two main paleostress fields marking two main stress regimes, strike-slip and extensional. The first is characterized by NNW–SSE compression and ENE–WSW extension and related to Middle Miocene-Recent sinistral movement along the Dead Sea transform and the opening of the Red Sea. The second paleostress field is a WNW–ESE compression and NNE–SSW extension restricted to the northern part of the investigated area. This stress field could be associated with the development of the Syrian Arc fold belt which started during the Turonian, or it may be due to an anticlockwise rotation of the first stress field. 相似文献
123.
Muha Abdullah Al Pavel Sharif A. Mukul Mohammad Belal Uddin Kazuhiro Harada Mohammed A. S. Arfin Khan 《山地科学学报》2016,13(6):1085-1095
We investigated the effect of tree cover, forest patch and disturbances on tree species richness in a highly diverse conservation area of northeast Bangladesh. A systematic sampling protocol was adopted and 80 sub-plots from twenty five 1 ha plots were used for the vegetation survey. Linear regression analysis was performed to understand the effect of patch area, disturbances and tree cover on tree species richness. Ordination using Redundancy analysis (RDA) and Non-metric Multi Dimensional Scaling (NMDS) were also performed to explore the tree species compositional similarities along the stand characteristics gradient and locations of the sample plots. Our study revealed that, forest patch size has greater influence on species richness. Areas with medium level of disturbances have shown greater species richness. In constrained ordination the selected explanatory variables regulated the richness of common species. Our findings can be useful for better forest management and restoration of landscapes of conservation needs using ecologically important species. 相似文献
124.
Petrochemistry and petrology of I-type granitoids in an arc setting: the composite Torul pluton, Eastern Pontides, NE Turkey 总被引:3,自引:0,他引:3
Abdullah Kaygusuz Wolfgang Siebel Cüneyt Şen Muharrem Satir 《International Journal of Earth Sciences》2008,97(4):739-764
The Upper Cretaceous Torul pluton, located in the Eastern Pontides, is of sub-alkaline affinity and displays features typical of volcanic arc granitoids. It is a composite pluton consisting of granodiorite, biotite hornblende monzogranite, quartz monzodiorite, quartz monzonite and hornblende biotite monzogranite. The oldest syenogranite (77.9 ± 0.3 Ma) and the youngest quartz diorite form small stocks within the pluton. Samples from the granodiorites, biotite hornblende monzogranites, quartz monzodiorites, quartz monzonites and hornblende biotite monzogranites have SiO2 between 57 and 68 wt% and display high-K calc-alkaline, metaluminous to peraluminous characteristics. Chondrite-normalized REE patterns are fractionated (Lacn/Lucn = 6.0?14.2) with pronounced negative Eu anomalies (Eu/Eu* = 0.59–0.84). Initial ?Nd(i) values vary between ?3.1 and ?4.1, initial 87Sr/86Sr values between 0.7058 and 0.7072, and δ18O values between +4.4 and +7.3‰. The quartz diorites are characterized by relatively high Mg-number of 36–38, low contents of Na2O (2.3–2.5 wt%) and SiO2 (52–55 wt%) and medium-K calc-alkaline, metaluminous composition. Chondrite-normalized REE patterns are relatively flat [(La/Yb)cn = 2.8–3.3; (Tb/Yb)cn = 1.2] and show small negative Eu anomalies (Eu/Eu* = 0.74–0.76). Compared to the other rock types, radiogenic isotope signatures of the quartz diorites show higher 87Sr/86Sr (0.7075–0.7079) and lower ?Nd(i) (–4.5 to –5.3). The syenogranites have high SiO2 (70–74 wt%) and display high-K calc-alkaline, peraluminous characteristics. Their REE patterns are characterized by higher Lacn/Lucn (12.9) and Eu/Eu* (0.76–0.77) values compared to the quartz diorites. Isotopic signatures of these rocks [?Nd(i) = ?4.0 to ?3.3; 87Sr/86Sr(i) = 0.7034?0.7060; δ18 O = + 4.9 to + 8.2] are largely similar to the other rock types but differ from that of the quartz diorites. Fractionation of plagioclase, hornblende, pyroxene and Fe–Ti oxides played an important role in the evolution of Torul granitoids. The crystallization temperatures of the melts ranged from 800 to 900°C as determined from zircon and apatite saturation thermometry. All these characteristics, combined with low K2O/Na2O, low Al2O3/(FeOT + MgO + TiO2), and low (Na2O + K2O)/(FeOT + MgO + TiO2) ratios suggest an origin through dehydration melting of mafic lower crustal source rocks. 相似文献
125.
John Douglas Sinan Akkar Gabriele Ameri Pierre-Yves Bard Dino Bindi Julian J. Bommer Sanjay Singh Bora Fabrice Cotton Boumédiène Derras Marcel Hermkes Nicolas Martin Kuehn Lucia Luzi Marco Massa Francesca Pacor Carsten Riggelsen M. Abdullah Sandıkkaya Frank Scherbaum Peter J. Stafford Paola Traversa 《Bulletin of Earthquake Engineering》2014,12(1):341-358
This article presents comparisons among the five ground-motion models described in other articles within this special issue, in terms of data selection criteria, characteristics of the models and predicted peak ground and response spectral accelerations. Comparisons are also made with predictions from the Next Generation Attenuation (NGA) models to which the models presented here have similarities (e.g. a common master database has been used) but also differences (e.g. some models in this issue are nonparametric). As a result of the differing data selection criteria and derivation techniques the predicted median ground motions show considerable differences (up to a factor of two for certain scenarios), particularly for magnitudes and distances close to or beyond the range of the available observations. The predicted influence of style-of-faulting shows much variation among models whereas site amplification factors are more similar, with peak amplification at around 1s. These differences are greater than those among predictions from the NGA models. The models for aleatory variability (sigma), however, are similar and suggest that ground-motion variability from this region is slightly higher than that predicted by the NGA models, based primarily on data from California and Taiwan. 相似文献
126.
Coal and gas outburst hazard in Zonguldak Coal Basin of Turkey,and association with geological parameters 总被引:1,自引:0,他引:1
Coal and gas outbursts have been a major geological hazard to underground coal mining for over 150 years and continue to cause serious problems in all over the world. In order to have a better understanding of the phenomenon, it is worthwhile making a historical review of the occurrences and a combat of the events. Many investigations and researches have been done to characterize and prevent the outburst occurrences in the worldwide, but there has been no detailed investigation about coal and gas outburst occurrences in Turkey. This paper presents the outburst data of coal mines in Turkey since 1969. Based on the observation of outburst occurrence in Turkey in the period from 1969 to 2012 as well as mining and geological conditions, detailed analysis of the possible causes of outburst accidents is conducted. The influences of some geological parameters such as the depth of occurrence, thickness and inclination of coal seams, the amount of ejected material (coal and gas), and tectonic disturbances on coal and gas outburst occurrences have been statistically investigated. The outburst occurrences throughout the world were reviewed and compared with the Turkish outburst experiences. Suggestions are put forward on future studies that could be of interest to government agencies regarding strategic policies, proper technical management practice, identification of outburst-prone coal seams, as well as prevention and control measures. 相似文献
127.
Ahmad H. Alashaikh Hasan M. Bilani Abdullah S. Alsalman 《Arabian Journal of Geosciences》2014,7(4):1559-1565
Some of the famous cylindrical projections are defined by a geometric process that is based on the perspective. This process can be imagined as a semitransparent sphere wrapped by a tube, secant, or tangent, with the same center; then all features of the sphere surface are projected onto the tube surface by light rays from a source in the equatorial plane. Just by changing the light source’s position and tube’s diameter, different maps can result. In every cylindrical perspective projections, distortions are functions of latitude only, thus, the value of distortion is fixed along a parallel (or a small circle). Therefore, distortion isograms are parallels (or small circles), symmetrical in relation of the equator. Consequently, it is suitable for territories having narrow band shape, extended by the equator (or an oblique equator). The proposed projection in this paper introduces another possible adjustment in cylindrical projections, in which axis of cylinder does not pass through the center of the sphere. This may satisfy case, where territories have a closed curve shape. By comparing the distribution of distortions in other famous perspective cylindrical projections (Lambert, stereographic, and central), with that in the proposed modified perspective cylindrical projection, it was found that distribution of area distortion in the proposed projection can be considered better than others. Therefore, in relation to area representation, the modified perspective cylindrical projection can be considered suitable for mapping regions, having shape close to an ellipse. 相似文献
128.
Mohammad S. Khan Mohamed H. Abdullah Gamal B. Ali 《Astrophysics and Space Science》2014,351(1):289-297
We derive analytical expression for the velocity dispersion of galaxy clusters, using the statistical mechanical approach. We compare the observed velocity dispersion profiles for 20 nearby (z≤0.1) galaxy clusters with the analytical ones. It is interesting to find that the analytical results closely match with the observed velocity dispersion profiles only if the presence of the diffuse matter in clusters is taken into consideration. This takes us to introduce a new approach to detect the ratio of diffuse mass, M diff , within a galaxy cluster. For the present sample, the ratio f=M diff /M, where M the cluster’s total mass is found to has an average value of 45±12 %. This leads us to the result that nearly 45 % of the cluster mass is impeded outside the galaxies, while around 55 % of the cluster mass is settled in the galaxies. 相似文献
129.
M. H. Abdullah M. B. Mokhtar S. H. J. Tahir A. B. T. Awaluddin 《Environmental Geology》1997,29(1-2):112-117
Sipadan Island is a small oceanic island with limited storage of fresh groundwater. A study was carried out to determine
the effect of tidal change on the groundwater quality of such an island using temperature, dissolved oxygen content, conductivity,
salinity, and pH values as indicators. Overall, the results indicated that the groundwater quality changes with tides, but
the trends of fluctuation differs between the observed parameters. It was found that the percentages of changes during the
period of study were 0.8% (temperature), 53% (dissolved oxygen), 61% (conductivity), 58% (salinity), and 1.7% (pH) at the
centre of the island; and 0.9% (temperature), 33% (dissolved oxygen), 40% (conductivity), 42% (salinity), and 9% (pH) at a
station 120 m from the coast, based on 2.9-m and 2.8-m tidal ranges at each station.
Received: 5 July 1995 · Accepted: 6 November 1995 相似文献
130.
Mohammed Hail Hakimi Wan Hasiah Abdullah 《International Journal of Earth Sciences》2013,102(1):333-348
Tertiary coals exposed in the north-central part of onshore Sarawak are evaluated, and their depositional environments are interpreted. Total organic carbon contents (TOC) of the coals range from 58.1 to 80.9 wt. % and yield hydrogen index values ranging from 282 to 510 mg HC/g TOC with low oxygen index values, consistent with Type II and mixed Type II–III kerogens. The coal samples have vitrinite reflectance values in the range of 0.47–0.67 Ro %, indicating immature to early mature (initial oil window). T max values range from 428 to 436 °C, which are good in agreement with vitrinite reflectance data. The Tertiary coals are humic and generally dominated by vitrinite, with significant amounts of liptinite and low amounts of inertinite macerals. Good liquid hydrocarbons generation potential can be expected from the coals with rich liptinitic content (>35 %). This is supported by their high hydrogen index of up to 300 mg HC/g TOC and Py-GC (S 2) pyrograms with n-alkane/alkene doublets extending beyond C30. The Tertiary coals are characterised by dominant odd carbon numbered n-alkanes (n-C23 to n-C33), high Pr/Ph ratio (6–8), high T m /T s ratio (8–16), and predominant regular sterane C29. All biomarkers parameters clearly indicate that the organic matter was derived from terrestrial inputs and the deposited under oxic condition. 相似文献