排序方式： 共有79条查询结果，搜索用时 250 毫秒
1.
A detailed fabric and microstructural analysis of the granitic mylonites was carried out on the southern side of Bes,parmak Mountain north of Selimiye (Milas). The mylonitic augen gneisses have?a blastomylonitic texture characterized by large retort-shape porphyroclasts or augen of feldspars, around which a more ductile, medium to fine-grained matrix of muscovite, biotite, quartz and feldspar is deflected. Feldspars behave in both plastic and brittle fashion, because size reduction occurs through grain boundary migration and/or subgrain rotation, and also through fracturing. Typical “core-and-mantle” structure, characterized by a large feldspar core surrounded by a mantle of fine recrystallized grains, is very characteristic. The majority of plagioclase twins obey the albite-twin law; however, the association with pericline-law twinning suggests that many of the twins are mechanical. Evidence of strain, such as deformation twins, bent or curved twins, undulatory extinction, deformation bands and kink bands occur characteristically in plagioclase. Myrmekite is ubiquitous at K-feldspar grain boundaries, most notably on the long sides of inequant grains parallel to the S-foliation direction, which invariably face the maximum finite shortening direction. Deformation of quartz in mylonitic augen gneisses commonly results in the development of core-and-mantle structure and “type-4” quartz ribbons of elongated, preferably oriented, newly recrystallized quartz aggregates suggesting a primary dynamic recrystallization. Undulatory extinction, deformation bands and lamellae are the strain-related features associated with quartz porphyroclasts. Micas, especially biotite, undergo internal deformation by bend gliding and kinking. Most of the micas are completely attenuated and aligned such that their (001) planes are subparallel or parallel to the margins of quartz ribbons and define the foliation in the rock. These microstructures of feldspars, quartz and mica in the mylonitic augen gneisses in this part of the southern Menderes Massif are broadly consistent with fabric development under upper-greenschist- to lower-amphibolite-facies conditions, rather than almandine–amphibolite facies, as was previously believed. This supports the previous contention of the authors that the protoliths of augen gneisses are younger granitoids and do not represent an exposed Precambrian Pan-African basement in the Menderes Massif. 相似文献
2.
3.
4.
Analysis of dry and wet climate characteristics at Uttarakhand (India) using effective drought index
Malik Anurag Kumar Anil Kisi Ozgur Khan Najeebullah Salih Sinan Q. Yaseen Zaher Mundher 《Natural Hazards》2021,105(2):1643-1662
Natural Hazards - Drought is a complex natural disaster that adversely affects human life and the ecosystem. A variety of drought indexes are available for monitoring meteorological drought events.... 相似文献
5.
Erdin Bozkurt 《International Journal of Earth Sciences》2001,89(4):728-744
The central Menderes Massif (western Turkey) is characterized by an overall dome-shaped Alpine foliation pattern and a N-NNE-trending stretching lineation. A section through the southern flank of the central submassif along the northern margin of Büyük Menderes graben has been studied. There, asymmetric non-coaxial fabrics indicate that the submassif has experienced two distinct phases of Alpine deformation: a top-to-the N-NNE contractional phase and a top-to-the S-SSW extensional event. The former fabrics are coeval with a regional prograde Barrovian-type metamorphism at greenschist to upper-amphibolite facies conditions. This event, known as the main Menderes metamorphism, is thought to be the result of internal imbrication of the Menderes Massif rocks along south-verging thrust sheets during the collision of the Sakarya continent in the north and the Anatolide-Tauride platform in the south across the Gzmir-Ankara suture during the (?)Palaeocene-Eocene. Top-to-the S-SSW fabrics, represented by a well-developed ductile shear band foliation associated with inclined and/or curved foliation, asymmetric boudins, and cataclasites, were clearly superimposed on earlier contractional fabrics. These fabrics are interpreted to be related to a low-grade (greenschist?) retrogressive metamorphism and a continuum of deformation from ductile to brittle in the footwall rocks of a south-dipping, presently low-angle normal fault that accompanied Early Miocene orogenic collapse and continental extension in western Turkey. A similar tectono-metamorphic history has been documented for the northern flank of the dome along the southern margin of the Gediz graben with top-to-the N-NNE extensional fabrics. The exhumation of the central Menderes Massif can therefore be attributed to a model of symmetric gravity collapse of the previously thickened crust in the submassif area. The central submassif is thus interpreted as a piece of ductile lower-middle crust that was exhumed along two normal-sense shear zones with opposing vergence and may be regarded as a typical symmetrical metamorphic core complex. These relationships are consistent with previous models that the Miocene exhumation of the Menderes Massif and Cycladic Massif in the Aegean Sea was a result of bivergent extension. 相似文献
6.
Viet-Ha Nhu Khabat Khosravi James R. Cooper Mahshid Karimi Ozgur Kisi Binh Thai Pham 《水文科学杂志》2020,65(12):2116-2127
ABSTRACT The predictive capability of a new artificial intelligence method, random subspace (RS), for the prediction of suspended sediment load in rivers was compared with commonly used methods: random forest (RF) and two support vector machine (SVM) models using a radial basis function kernel (SVM-RBF) and a normalized polynomial kernel (SVM-NPK). Using river discharge, rainfall and river stage data from the Haraz River, Iran, the results revealed: (a) the RS model provided a superior predictive accuracy (NSE = 0.83) to SVM-RBF (NSE = 0.80), SVM-NPK (NSE = 0.78) and RF (NSE = 0.68), corresponding to very good, good, satisfactory and unsatisfactory accuracies in load prediction; (b) the RBF kernel outperformed the NPK kernel; (c) the predictive capability was most sensitive to gamma and epsilon in SVM models, maximum depth of a tree and the number of features in RF models, classifier type, number of trees and subspace size in RS models; and (d) suspended sediment loads were most closely correlated with river discharge (PCC = 0.76). Overall, the results show that RS models have great potential in data poor watersheds, such as that studied here, to produce strong predictions of suspended load based on monthly records of river discharge, rainfall depth and river stage alone. 相似文献
7.
A. T. M. Sakiur Rahman Takahiro Hosono Ozgur Kisi Boateng Dennis A. H. M. Rahmatullah Imon 《水文科学杂志》2020,65(12):1994-2006
ABSTRACT This study aimed to evaluate the potential of the recently introduced Prophet model for estimating reference evapotranspiration (ETo). A comparative study was conducted for benchmarking the model results with support vector regression (SVR) and temperature-based empirical models (Thornthwaite and Hargreaves) in southern Japan. The performance of the Prophet, SVR and temperature-based empirical models was evaluated by Nash–Sutcliffe efficiency (NSE) and coefficient of determination (R2). The results indicate that temperature-based Prophet and SVR models have greater accuracy than the empirical models. The Prophet model with sole input of relative humidity, sunshine hours or windspeed showed acceptable accuracy (NSE > 0.80; R2 > 0.80), while SVR models with similar inputs showed greater errors. Accuracy improved with increasing number of input parameters, giving excellent performance (NSE > 0.95; R2 > 0.95) with all input parameters. Hence, the Prophet model is a new promising approach for modelling ETo with limited input variables. 相似文献
8.
Outlier trimming and homogeneity checking/correction were performed on the monthly precipitation time series of various lengths from 267 stations in Turkey. Outlier values are usually found during dry summer months, and are concentrated mostly over the southern parts of the country, where the dry period is most pronounced, implying natural extremes rather than wrong measurements. Homogeneity analysis was done using the Standard Normal Homogeneity Test, on an individual monthly basis, which led to many non‐testable series due to lack of reference stations, especially during summer months. Yet, remaining testable months were usually helpful for the assessment of homogenity, revealing a well distributed set of stations that proved to be homogeneous. There were still a number of stations which either could not be tested efficiently, or were classified as inhomogeneous. Lack of metadata is argued to be largely responsible for inefficient homogeneity testing. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
9.
The Menderes Massif, in western Anatolia, has been described as a lithological succession comprising a basal ‘Precambrian gneissic core of sedimentary origin’ overlain in sequence by ‘Palaeozoic schist’ and ‘Mesozoic-Cenozoic marble’ forming the envelope. The boundary between core and schist envelope was interpreted as a major unconformity, the ‘Supra-Pan-African unconformity’. By contrast, our field observations and geochemical data show that around the southern side of Besparmak Mountain, north of Selimiye (Milas), the protoliths of highly deformed, mylonitized augen gneisses are granitoid rocks intrusive into the adjacent Palaeozoic metasedimentary schists. The field relationships indicate the age of intrusion to be younger than late Permian and there is no evidence for the existence of either an exposed Precambrian basement or the ‘Supra-Pan-African unconformity’ in this sector of the Menderes Massif. 相似文献
10.
Sanikhani Hadi Kisi Ozgur Amirataee Babak 《Theoretical and Applied Climatology》2018,132(1-2):491-502
Theoretical and Applied Climatology - Investigation of the impact of climate change on water resources is very necessary in dry and arid regions. In the first part of this paper, the climate model... 相似文献