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The variability of ruthenium in chromite from chassignite and olivine‐phyric shergottite meteorites: New insights into the behavior of PGE and sulfur in Martian magmatic systems 
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下载免费PDF全文 Raphael J. Baumgartner Marco L. Fiorentini David Baratoux Ludovic Ferrière Marek Locmelis Andrew Tomkins Kerim A. Sener 《Meteoritics & planetary science》2017,52(2):333-350
The Martian meteorites comprise mantle‐derived mafic to ultramafic rocks that formed in shallow intrusions and/or lava flows. This study reports the first in situ platinum‐group element data on chromite and ulvöspinel from a series of dunitic chassignites and olivine‐phyric shergottites, determined using laser‐ablation ICP‐MS. As recent studies have shown that Ru has strongly contrasting affinities for coexisting sulfide and spinel phases, the precise in situ analysis of this element in spinel can provide important insights into the sulfide saturation history of Martian mantle‐derived melts. The new data reveal distinctive differences between the two meteorite groups. Chromite from the chassignites Northwest Africa 2737 (NWA 2737) and Chassigny contained detectable concentrations of Ru (up to ~160 ppb Ru) in solid solution, whereas chromite and ulvöspinel from the olivine‐phyric shergottites Yamato‐980459 (Y‐980459), Tissint, and Dhofar 019 displayed Ru concentrations consistently below detection limit (<42 ppb). The relatively elevated Ru signatures of chromite from the chassignites suggest a Ru‐rich (~1–4 ppb) parental melt for this meteorite group, which presumably did not experience segregation of immiscible sulfide liquids over the interval of mantle melting, melt ascent, and chromite crystallization. The relatively Ru‐depleted signature of chromite and ulvöspinel from the olivine‐phyric shergottites may be the consequence of relatively lower Ru contents (<1 ppb) in the parental melts, and/or the presence of sulfides during the crystallization of the spinel phases. The results of this study illustrate the significance of platinum‐group element in situ analysis on spinel phases to decipher the sulfide saturation history of magmatic systems. 相似文献
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Bulent Tutmez Uzay Kaymak A. Erhan Tercan 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(7):1013-1023
Spatial data analysis focuses on both attribute and locational information. Local analyses deal with differences across space whereas global analyses deal with similarities across space. This paper addresses an experimental comparative study to analyse the spatial data by some weighted local regression models. Five local regression models have been developed and their estimation capacities have been evaluated. The experimental studies showed that integration of objective function based fuzzy clustering to geostatistics provides some accurate and general models structures. In particular, the estimation performance of the model established by combining the extended fuzzy clustering algorithm and standard regional dependence function is higher than that of the other regression models. Finally, it could be suggested that the hybrid regression models developed by combining soft computing and geostatistics could be used in spatial data analysis. 相似文献
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AbstractThe NE-SW-trending Burdur–Fethiye fault zone is one of the major active fault zones of southwestern Turkey and the ancient city of Cibyra is located on this zone. Segments of the Burdur–Fethiye fault zone have ruptured in the historical period and during the 20th century. A detailed investigation in the ancient city of Cibyra showed the presence of faults sinistrally offset sitting rows of the stadium up to 50 cm. In addition, there are broken corners of blocks, collapsed walls, broken columns, and tilted and toppled blocks in existing major buildings in the city centre. Field observations showed that fractures and associated damage at Cibyra Produced by a post-Roman earthquake, possibly during the 417-A.D.-earthquake which had an intensity of 9 on the MSK scale. © 2001 Éditions scientifiques et médicales Elsevier SAS. 相似文献
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This article addresses a new reserve estimation method which uses fuzzy modeling algorithms and estimates the reserve parameters
based on spatial variability. The proposed fuzzy modeling approach has three stages: (1) Structure identification and preliminary
clustering, (2) Variogram analysis, and (3) Clustering based rule system. A new clustering index approach and a new spatial
measure function (point semimadogram) are proposed in the paper. The developed methodology uses spatial variability in each
step and takes the fuzzy rules from input-output data. The model has been tested using both simulated and real data sets.
The performance evaluation indicates that the new methodology can be applied in reserve estimation and similar modeling problems 相似文献
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Delineation of the groundwater potential zones is one of the most essential process for the sustainable management of the groundwater sources. However, groundwater studies are quite hard and complex for many regions besides consuming time and cost. This study focused on the groundwater potential mapping in Bey?ehir Lake Basin. Mainly, fuzzy-analytic hierarchy process (fuzzy-AHP) integrated with GIS was used to determine potential zones for groundwater. Seven parameters, namely lithology, lineament, drainage density, land use, slope, soil type, and rainfall were evaluated and Groundwater Potential Index (GWPI) was calculated using weight and rating coefficients of each parameter. According to obtained results, GWPI varies from 0.07665 to 0.28243 in the basin. The low, moderate, and high groundwater potential classes were determined with quantile classification method. The groundwater potential map demonstrates that the high groundwater potential area is located around the lake shore, in the alluvium and limestone fields because high permeability rates depend on soil type, low slope, karstic structure, and agricultural activities in these regions. In addition, the distribution of the springs confirms with groundwater potential area determined with this study. 相似文献
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In the predicting of geological variables, artificial neural networks (ANNs) have some drawbacks including possibility of getting trapped in local minima, over training, subjectivity in the determining of model parameters and the components of its complex structure. Recently, support vector machines (SVM) has been found to be popular in prediction studies due to its some advantages over ANNs. Because the least squares SVM (LS‐SVM) provides a computational advantage over SVM by converting quadratic optimization problem into a system of linear equations, LS‐SVM method is also tried in study. The main purpose of this study is to examine the capability of these two SVM algorithms for the prediction of tensile strength of rock materials and to compare its performance with ANN and linear regression (MLR) models. Total porosity, sonic velocity, slake durability index and aggregate impact value were used as input in modeling applications. Favorite performance evaluation measures were employed to assess developed models. The results determined in study indicate that the SVM, LS‐SVM and ANN methods are successful tools for prediction of tensile strength variable and can give good prediction performances than MLR model. Although these three methods are powerful artificial intelligence techniques, LS‐SVM makes the running time considerably faster with the higher accuracy. In terms of accuracy, the LS‐SVM model resulted in error reductions relative to that of the other models. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Volkan Karabacak
nder Ynlü Eray Dkü Nafiye Güne K&#x;yak Erhan Altunel ükrü
züdoru Cahit alar Yal&#x;ner Hüsnü Serdar Akyüz 《Geoarchaeology》2013,28(6):531-543
The ancient city of Kibyra in southwest Turkey has the potential to reveal the location and date of historical earthquakes. The most compelling evidence for earthquake faulting is observed in the city's Roman stadium. Damage related to seismic shaking is characterized by systematically collapsed columns, dilated and collapsed walls, and by rotated and displaced blocks in the stadium. Detailed archaeoseismological observations suggest that Kibyra was affected by earthquakes that were also recorded in historical earthquake catalogs. Although there is no historical record of a large earthquake after the 5th century A.D., Optically stimulated luminescence (OSL) dating of deposits under the collapsed blocks suggests a later seismic event. OSL results indicate that another large event occurred in southwest Turkey, probably around the 10–11th century A.D., and caused extensive damage (Io = VIII‐IX) to the Kibyra stadium. 相似文献
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Nazmi Erhan Yasitli 《Arabian Journal of Geosciences》2013,6(7):2699-2708
As a result of urbanization all over the world, complicated transportation system have been constructed to supply the need of the public transport. Metro tunnel is the most important effective solution method for public transportation. However, the surface settlement around the metro line in urban areas should be within the allowable limits and it should not damage nearby structures. The tunnel excavation and the support system have to provide a reliable working condition for the workers and the people living along the metro line. Although New Austrian Tunneling Method (NATM) is a very useful method in tunnel excavation, it may be insufficient in weak rock condition. Umbrella Arch Method (UAM) has been recently a viable alternative in various important areas. In this paper, the results of 3-D numerical modeling of surface settlement at the transition zone in Istanbul Metro excavated by NATM and UAM are presented by using a finite difference code called FLAC3D. The results showed that umbrella arch pipe is very effective to minimize the surface settlement. According to the actual measurement result and numerical modeling result, umbrella arch pipe reduced the surface settlement by 71% and 63%, respectively. In addition, the numerical modeling result represented 79.5% of the actual value obtained from in situ for NATM region and 86.0% of in situ value for UAM region. 相似文献