Natural and fallout radioactivity levels and radiation hazard evaluation in soil samples     

M. Karataşlı  Ş. Turhan  A. Varinlioğlu  Z. Yeğingil 《Environmental Earth Sciences》2016,75(5):424

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Geomorphological features and weathering of the Southern Submassif of the Menderes Massif (SW Turkey)     

Murat Gül  Göksu Uslular 《Arabian Journal of Geosciences》2016,9(16):682

The Southern Submassif crops out in the SW of Turkey. This submassif consists of mostly large feldspar-bearing orthogneisses and to a lesser extent tourmaline-orthoclase-plagioclase-, quartz-, muscovite-, and biotite-bearing leucogranites. The orthogneiss forms domed bald hills. The leucogranites crop out (approximately 2 km²) in the southeastern lowland of the hill. Those units show various geomorphological features that are typically reported in granitoids. Many studies about the Menderes Massif are related with petrography and metamorphic history. The geomorphological features are not taken into consideration. Field observation, thin section analysis, joint set-foliation measurements, and Schmidt Hammer value determination were done in this study. The pillar structures (castellated and domed types) are among larger structures observed on flanks of the domed bald hill. Geomorphological features such as weathering pits, tafoni, honeycomb structures, polygonal cracks, flared slopes, exfoliation, and boulders are observed. The metamorphism causes mineral alignments that affect the strength of the rock. The studied rocks have high strength in perpendicular direction to foliation. The complex tectonic history caused developments of several joint sets. Differences in mineral strength (e.g., high in quartz, low in biotite and feldspar) increase weathering effect. Underground water percolation through the fractures weakens the rock and causes subsurface weathering. After exhumation, disintegrated materials are stripped off, and then flared slopes, polygonal cracks, and pillar structures are exposed. Surface weathering by wind and water increases the weathering effects and gives rise to a formation of rounded rock edges called spheroidal weathering. Contrary to other granitoid areas, the metamorphism promotes the formation of geomorphological features in the study area.  相似文献   

Model for the Processing and Estimation of Dual Frequency Echo Sounder Observations in Detailed Bathymetries   总被引：1，自引：0，他引：1  

Raúl Pereda García  Felipe Piña García  Julio Manuel De Luis Ruiz  Raúl Husillos Rodríguez 《Marine Geodesy》2016,39(3-4):305-320

The dataset acquired by an echo sounder generally comprises outliers and erroneous measurements which must be automatically processed. The main aim of this research is the development and validation of an algorithm which permits detecting outliers, estimating their real value from data acquired with a multifrequency echo sounder, and verifying the measure according to the desired accuracy. The process considers the nature of the seabed and improves the density and number of lectures without globally compromising the precision, but enhancing it in areas with anomalous measurements. Twenty-nine percent of this type of measurements, which would have been otherwise rejected, have been estimated.  相似文献   

Comparison of Satellite-Only Gravity Field Models Constructed with All and Parts of the GOCE Gravity Gradient Dataset     

Sean L. Bruinsma  Christoph Förste  Sandrine Mulet  Marie-Hélène Rio  Oleg Abrikosov  Jean-Charles Marty 《Marine Geodesy》2016,39(3-4):238-255

The impact of GOCE Satellite Gravity Gradiometer data on gravity field models was tested. All models were constructed with the same Laser Geodynamics Satellite (LAGEOS) and Gravity Recovery and Climate Experiment (GRACE) data, which were combined with one or two of the diagonal gravity gradient components for the entire GOCE mission (November 2009 to October 2013). The Stokes coefficients were estimated by solving large normal equation (NE) systems (i.e., the direct numerical approach). The models were evaluated through comparisons with the European Space Agency's (ESA) gravity field model DIR-R5, by GPS/Leveling, GOCE orbit determination, and geostrophic current evaluations. Among the single gradient models, only the model constructed with the vertical ZZ gradients gave good results that were in agreement with the formal errors. The model based only on XX gradients is the least accurate. The orbit results for all models are very close and confirm this finding. All models constructed with two diagonal gradient components are more accurate than the ZZ-only model due to doubling the amount of data and having two complementary observation directions. This translates also to a slower increase of model errors with spatial resolution. The different evaluation methods cannot unambiguously identify the most accurate two-component model. They do not always agree, emphasizing the importance of evaluating models using many different methods. The XZ gravity gradient gives a small positive contribution to model accuracy.  相似文献   

Probabilistic evaluation of observed earthquake damage data in Turkey     

Betül Şengezer  Atilla Ansal 《Natural Hazards》2007,40(2):305-326

Empirical, theoretical or hybrid methods can be used for the vulnerability analysis of structures to evaluate the seismic damage data and to obtain probability damage matrices. The information on observed structural damage after earthquakes has critical importance to drive empirical vulnerability methods. The purpose of this paper is to evaluate the damage distributions based on the data observed in Erzincan-1992, Dinar-1995 and Kocaeli-1999 earthquakes in Turkey utilizing two probability models—Modified Binomial Distribution (MBiD) and Modified Beta Distribution (MBeD). Based on these analyses, it was possible (a) to compare the advantages and limitations of the two probability models with respect to their capabilities in modelling the observed damage distributions; (b) to evaluate the damage assessment for reinforced concrete and masonry buildings in Turkey based on these models; (c) to model the damage distribution of different sub-groups such as buildings with different number of storeys or soil conditions according to the both models. The results indicate that (a) MBeD is more suitable than the MBiD to model the observed damage data for both reinforced concrete and masonry buildings in Turkey; (b) the sub-groups with lower number of stories are located in the lower intensity levels, while the sub-groups with higher number of stories depending on local site condition are concentrated in the higher intensity levels, thus site conditions should also be considered in the assessment of the intensity levels; (c) the detailed local models decrease the uncertainties of loss estimation since the damage distribution of sub-groups can be more accurately modelled compared to the general damage distribution models.  相似文献   

SHRIMP U-Pb Zircon Age of the Ka''erjiao Intrusion in the Sawur Region in West Junggar,Xinjiang          下载免费PDF全文

ZHOU Taof  TAN Lugui  FAN Yu  YUAN Feng  YANG Wenping  HE Lixin  YUE Shucang School of Resources  Environmental Engineering  Hefei University of Technology  Hefei  Anhui No. Geological Party  Xinjiang Bureau of Geological Exploration  Altay  Xinjiang 《《地质学报》英文版》2007,81(2)

Acid intrusions are widespread in the Sawur region, Xinjiang. The Ka'erjiao intrusion is mainly composed of albite granite porphyry, K-feldspar granite porphyry, ivernite and granite porphyry. Being a transitional product between magma intrusion and eruption in the Sawur region, the Ka'erjiao intrusion was formed at the telophase of the late Carboniferous to the begining of early Permian as determined by the SHRIMP U-Pb zircon dating, with an age of 302.6±7.6 Ma (1σ). The intrusion consists of alkali-enriched rock, whose REE distribution patterns are of the LREE enrichment type, theδEu value is low and Nd, Sr, Pb isotopes reflect its mantle source characteristics. Theδ18O value of intrusion is low as a result of isotope exchange with meteoric water. The geochemical characteristics show that it was formed in a post-collisional tectonic setting. Taking combined considerations of current studies of A-type granites and Permian volcanic rocks, we think that in the telophase of the late Carboniferous to the beginning of the early Permian, the Sawur region was within the extension or compressional to extensional period of a post-collisional stage. The Ka'erjiao intrusion from mantle sources can confirm the vertical continental crust growth in the late Paleozoic. The Sawur region in west Junggar is consistent with east Junggar in post-collisional tectonic evolution process.  相似文献   

Magnetic,paleomagnetic and palynologic studies of Paleolithic depositions of the Akhshtyrskaya cave (Russia)     

Genrietta A. Pospelova  Elżbieta Król  Galina M. Levkovskaya  Jadwiga Kruczyk  Magdalena Kądziałko-Hofmokl  Sergey A. Kulakov 《Acta Geophysica》2007,55(4):619-639

The paper presents the results of experimental rock-magnetic, paleomagnetic and palynologic study of Paleolithic sediments sampled along two profiles in the Akhshtyrskaya cave, situated in the vicinity of Black Sea shore. In the upper part of profiles, some magnetite was observed; in the middle and lower parts, strongly oxidized non-stoichiometric magnetite and hematite prevail. Thin maghemite covers on the surface of fine magnetite grains are present in the majority of specimens. Natural remanence has one characteristic component (CHRM), mostly of chemical origin, although in few specimens containing magnetite it may be sedimentary. Directions of CHRM obtained by standard paleomagnetic methods revealed anomalous pattern only in layer 3/2, which is slightly older than the overlying layer 3/1 whose age was established as (35±2)×10³ years BP by the U-Th method. This suggests that this paleomagnetic anomaly (PMA) can be correlated with Kargapolovo excursion dated on about (45−39)×10³ years BP. In the remaining overlying and underlying layers, directions of CHRM are grouped around the present geomagnetic field. Depth distributions of scalar magnetic parameters generally coincide with the lithological division of the profiles. Palynologic study revealed the presence of 22 pollen zones. Five thermomers separated with colder periods were found in the middle and lower parts of profile. The non-magnetite composition of magnetic fraction of the majority of studied sediments — oxidized nonstoichiometric magnetite and hematite — resulted in the lack of correlations between paleoclimatic and scalar magnetic characteristics.  相似文献   

西准噶尔萨吾尔地区Ⅰ型花岗岩同位素精确定年及其意义   总被引：5，自引：11，他引：5  

袁峰  周涛发  谭绿贵  范裕  杨文平  何立新  岳书仓 《岩石学报》2006,22(5):1238-1248

西准噶尔萨吾尔地区地处新疆阿勒泰地区吉木乃县及塔城地区和丰县。区内酸性侵入岩较发育,森塔斯岩体中二长花岗岩锆石SHRIMP U-Pb年龄为328．2±5．7Ma(1σ),沃肯萨拉岩体中二长花岗岩锆石SHRIMP U-Pb年龄为323．8±6．2Ma(1σ),塔斯特岩体二长花岗岩全岩~(40)Ar/~(39)Ar年龄为313．6±3．2Ma(1σ),形成于早石炭世晚期。各岩体均具有Ⅰ型花岗岩特征,岩石偏碱性,Nd、Sr、Pb同位素显示出其幔源特征,具正常O同位素组成。森塔斯岩体、沃肯萨拉岩体和塔斯特岩体属于后碰撞花岗岩,其形成表明早石炭世晚期萨吾尔地区乃至西准噶尔地区已处于后碰撞构造环境,它们可能是后碰撞阶段挤压-伸展转变期的产物。森塔斯岩体、沃肯萨拉岩体和塔斯特岩体的岩石地球化学特征与准噶尔地区已知的Ⅰ型花岗岩(成岩年龄为300Ma左右)相似,但其发育显示准噶尔地区后碰撞Ⅰ型花岗岩的形成应始于早石炭世晚期。研究区早石炭世晚期后碰撞Ⅰ型花岗岩的确定为区域晚古生代地壳的垂向增生提供了新的证据。  相似文献   

瞬变电磁勘查方法在依力矿区中的应用     

WANG Ju LI Chao-cheng YANG Zhong-xi SUN Cheng-xian LI Hui-jie YANG Na .Jilin Province Coalfield Geological  Geophysical Exploration  Changchun  China .No. Prospecting Company of Coal Geological in Jilin Province  Yanji  Jilin  China 《吉林大学学报(地球科学版)》2006,(Z2)

依力矿区以往勘查资料很少,通过瞬变电磁测深方法勘查确定的断层,与钻探资料确定的断层,在位置基本上吻合,但方向上有一定的差异。只有物探与钻探相结合,才能使勘查成果质量有很大提高。  相似文献   

GPS RTK技术在龙家堡三维地震测量中的应用     

YAO Pai LIANG Zuo-Ping LI Hai-yan ZHAO Fu-you .Geophysical Prospecting Company of Coal Geology of Jilin Province  Changchun  China .No. Prospecting Company of Coal Geology of Jilin Province  Yanji  Jilin  China 《吉林大学学报(地球科学版)》2006,(Z2)

通过实例论述了用RTK放样三维地震测线的作业流程,并从三个方面分析了RTK放样点所达到的精度完全满足规范的要求,指出RTK测量具有广阔的发展前景。  相似文献