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1.
Dams constructed on the seismically active regions have a high-risk potential for downstream life and property. Strong ground motion can result in instability of the dam and strength loss of foundation. Active faults within the foundation of dam have the potential to cause damaging displacement of the structures. Appropriate design measures should be considered to obtain rational solution to the problem of catastrophic release of water from the reservoir, and especially to resist earthquake loads. Safety concerns for dams under the earthquake loads involve the seismic hazard evaluation of dam site for the overall stability of structure. Various types of analyses can be used, ranging from a simplified analysis to more complex procedures based on ground motion parameters and response spectra. This paper briefly evaluates seismic hazard analyses for dam structures, and introduces the analyses for thirty-six dams with height ranging from 15 to 195 m in Kızılırmak basin, Turkey. The seismic hazard analyses have indicated that peak ground acceleration varies within a wide range (0.09–0.45 g) for the dam sites of the basin.  相似文献   

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4.
A numerical simulation has been carried out to investigate the effects of below-sea-level (b.s.l.) excavation on the raw material quality of a cement quarry in Turkey. The model simulates variations in the hydrodynamic and hydrogeochemical mechanisms in the coastal aquifer upon BSL excavation. In this context, behavior of the seawater intrusion zone, changes in water levels, and salt concentrations have been simulated. In the development of the model, previous geological and hydrogeological reports of the quarry site and the near vicinity have been considered. Eleven new wells (BH-1,...BH-11) have been drilled to reveal hydrogeological features of the area and also for periodical observations of the water levels and hydrogeochemical monitoring. These wells were utilized to develop and calibrate the model to the field conditions. Physical and hydrogeochemical parameters used in the model have been evaluated using available hydrogeological data, the field test results and the related literature. The model has been verified using the field observations. It is based on the virgin conditions of the aquifer as well as on the data for years 1990 and 2001. An average raw material production rate for the cement factory was considered during development of the model, and for making future predictions. Two alternative production scenarios have been considered and probable effects of above-sea-level (a.s.l.) and b.s.l. excavations on seawater intrusion into the aquifer have been studied. Future prediction studies are based on these two production scenarios that assume 43 years of total production (30 years of a.s.l. and 13 years of b.s.l. production) in the quarry. The first scenario, Scenario I, assumes that starting from 2001, the next 30 years would be devoted only to ASL and then the remaining 13 years would be used for b.s.l. production. Scenario II, on the other hand, assumes simultaneous operations both at a.s.l. and b.s.l. levels for the next 43 years after 2001. Effects of b.s.l. production in the quarry site have been simulated accordingly, and seawater intrusion into the aquifer as well as water discharge rates have been predicted for –10, –20 and –30 m production levels.  相似文献   

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6.
《Geodinamica Acta》2001,14(1-3):103-131
We investigate the left-lateral slip on the 240-km-long, NE–SW-trending, Malatya–Ovacık fault zone in eastern Turkey. This fault zone splays southwestward from the North Anatolian fault zone near Erzincan, then follows the WSW-trending Ovacık valley between the Munzur and Yılan mountain ranges. It bends back to a SW orientation near Arapkir, from where we trace its main strand SSW beneath the Plio-Quaternary sediment of the Malatya basin. We propose that this fault zone was active during ∼5–3 Ma, when it took up 29 km of relative motion between the Turkish and Arabian plates; it ceased to be active when the East Anatolian fault zone formed at ∼3 Ma. The geometry of the former Erzincan triple junction, which differs from the modern Karlıova triple junction, where the North and East Anatolian fault zones intersect, suggests a possible explanation for why slip on the Malatya–Ovacık fault zone was unable to continue. We interpret the SW- and SSW-trending segments of the Malatya–Ovacık fault zone as transform faults, which define an Euler pole ∼1 400 km to the southeast. Its central part along the Ovacık valley, which is ∼30° oblique to the adjoining transform faults, is interpreted as the internal fault of a stepover. The adjoining mountain ranges, which now rise up to ∼3 300 m, ∼2 000 m above the surrounding land surface, are largely the result of the surface uplift which accompanied the components of shortening and thickening of the upper crustal brittle layer that occurred around this stepover while the left-lateral faulting was active.  相似文献   

7.
The K?rka borate deposit was deposited in a Miocene lacustrine basin which is closely associated with volcanic activity which lasted from Paleogene to the beginning of Quaternary. Borate mineralization alternates with claystone, mudstone, tuff and fine-layered limestone and mostly shows a lenticular structure. The mineral paragenesis is composed of borax, tincalconite, ulexite, kurnakovite, probertite, tunellite, colemanite, dolomite, smectite group minerals, illite and some firstly reported minerals for the K?rka deposit including hydrochloroborite, brianroulstonite, hilgardite-4M and searlesite minerals. In comparison to average values of earth crust, concentrations of Cs, Sr, Li, As and Se were significantly enriched with respective rates of 21, 15, 14, 3 and 188 folds. Regarding KY, KS1 and KS2 locations, there are differences in both element abundances and their geochemical tendencies which are attributed to variations in discharge regime and physico-chemical conditions of the depositional environment. Independent behaviour of B2O3 might indicate that boron is not associated with clays and carbonates and, therefore, most part of boron must be derived from volcanic activity (hydrothermal solutions, gases). REE data indicate that the K?rka borate deposit was formed in a sedimentary environment where highly alkaline (high pH) hydrothermal solutions also took part in borate precipitation process.  相似文献   

8.
The concentrations and distribution of natural and artificial radionuclides in sediment and water samples collected from Fırtına River in the Eastern Black Sea region of Turkey were investigated with an aim of evaluating the environmental radioactivity and radiation hazard. Natural gross α and gross β activities were determined for 21 different water samples, and the activity concentrations were obtained for 226Ra, 214Pb, 214Bi, 228Ac, 208Tl, 40K and 137Cs in 20 different sediment samples. The obtained results showed that natural gross α and gross β activity concentrations in water samples range from 12.4 ± 3.4 to 66.2 ± 9.2 mBq l−1 and from 27.9 ± 3.3 to 133.3 ± 4.1 mBq l−1, respectively. The mean activity concentrations were 32.6 ± 3.8 mBq l−1 for gross α and 69.9 ± 4.4 mBq l−1 for gross β. Generally, the gross β activities were higher than the corresponding gross α activities. The average concentrations of 238U and 232Th daughter products vary from 11 to 167 Bq kg−1 and from 16 to 107 Bq kg−1, respectively. The concentrations of 40K and 137Cs vary from 51 to 1,605 Bq kg−1 and from 0.8 to 42 Bq kg−1, respectively. Sediment characterization was also investigated using grain size, thin section and XRD analysis.  相似文献   

9.
It is important to know the distribution and transfer of radionuclides such as uranium, thorium, and potassium, which exist naturally in the environment we live in. For this reason, measurements of these natural radionuclides have been carried out for 15 gravel samples collected from Konyaalt? Beach, Antalya. In order to measure the natural activity concentrations of potassium-40, uranium-238, and thorium-232 radionuclides, we performed the measurements by applying a gamma spectrometry method with a “3?×?3” NaI(Tl) detector, which is a multichannel analytical detector in the Suleyman Demirel University gamma spectrometry laboratory. The minimum, maximum, and mean values for the 226Ra activity concentration were measured as 19.74 Bq/kg, 37.03 Bq/kg, and 31.64 Bq/kg, respectively. The minimum, maximum, and mean values for the 232Th activity concentration were measured as 12.76 Bq/kg, 34.32 Bq/kg, and 26.67 Bq/kg, respectively. The minimum, maximum, and mean values for the 40K activity concentration were measured as 196.37 Bq/kg, 421.13 Bq/kg, and 350.42 Bq/kg, respectively. Dose parameters and radiation damage indices were calculated using experimentally measured activity results and the resulting dose and hazard index values were compared with the determined limit values. It can be concluded that no risk may threat in terms of the hazard index values. In addition, all results obtained in terms of calculated dose values except for annual gonadal dose are below the recommended limit values.  相似文献   

10.
The Büyük Menderes and Gediz (Ala?ehir) grabens are two significant segments of the Western Anatolian extensional province. They merge around Buldan-Sar?caova in the east. Outcropping Neogene sedimentary units in this area display a rather complex structure. This paper summarizes the importance and meaning of the data obtained during a detailed investigation of the Neogene units and aims to improve our understanding of the neotectonic evolution of Western Anatolia. The Buldan-Sar?caova Neogene sequence is composed of three different sedimentary units: (1) the Lower Unit, (2) the Middle Unit, and (3) the Upper Unit. The Lower Unit crops out on the Buldan horst which is located between the Büyük Menderes and Ala?ehir grabens. The sequence starts as a coarse conglomerate and sandstone (?salar Formation) and continues as lagoonal-lacustrine mudstone, interbedded with coal seams and shales (Bostanyeri Formation) and also with lacustrine limestones. The age of this succession is Lower-Middle Miocene. The development of the basin is structurally controlled by NNW-trending normal faults. The Middle Unit begins with a conglomerate–mudstone sequence (K?z?lburun Formation), followed by a sandstone–mudstone–marl sequence (Sarayköy Formation). A lacustrine limestone–marl unit occurs at the top (Aktepe Formation). Some thin gypsum lenses and layers are observed in the Sarayköy Formation. The unit contains some brackish-water fossils. The rocks of the Middle Unit crop out mostly at the low altitudes of the Buldan horst, i.e. the southeast piedmont, around the junction of the Büyük Menderes and the Gediz grabens. The Middle Unit was deposited in fluvial and lacustrine environments during the Late Miocene–Pliocene period. These rocks were formed in response to the uplift of the Buldan horst. The Upper Unit, which is composed of conglomerates, was deposited within the Büyük Menderes Graben–Gediz Graben depressions as alluvial fill.  相似文献   

11.
A study of the hydrochemical evaluation of waters in the I??kl? Lake and surrounding area was carried out with the objective of identifying the geochemical processes and their relation with water quality in the region. The multivariate statistical techniques were used in the hydrochemical evaluation of waters. Statistical analysis of water quality parameters was made to seeing the interrelationship between different variables in order to explain the water quality and pollution status of study area. For this purpose, water samples were taken from lake, river, stream, and springs which are represented by investigated area and water qualities were evaluated. Generally, Ca2+, Mg2+, and Cl?, HCO3 ? ions are dominant within surface water and water sources. Arsenic concentration increase is determined in I??kl? spring and Kufi stream water samples. Also, aluminum concentration is high level in the Kufi stream water samples. This increase was related to igneous rocks as geogenic origin. Also, geogenic contamination was identified in R-mode factor and cluster analyses. There is high correlation between electrical conductivity and major ions of waters.  相似文献   

12.
Human activities and agriculture have had direct and indirect effects on the rates of contamination of groundwater in the Incesu-Dokuzp inar spring area. Direct effects include dissolution and transport of excess quantities of fertilizers with associated materials and hydrological alterations related to irrigation and drainage. Indirect effects may include changes in water–rock reactions in soils and aquifers caused by increased concentrations of dissolved oxidants, protons, and major ions. Agricultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO 3, N 2, Cl, SO 4 2, H +, K, Mg, Ca, Fe, Cu, B, Pb, and Zn, as well as a wide variety of pesticides and other organic compounds. For reactive contaminants like NO 3, it is recommended that a combination of hydrochemical and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. The water type of Dokuzp inar springs is mainly Na–Mg–Ca–Cl–HCO 3. Note that the water types of the springs were directly related to the hydrogeochemical properties of outcrops at the study area. Thus, the high concentration of Ca 2+ and HCO 3 is mainly related to the high CO 2 contents in the marbles, whereas the high Na concentration arises from the existing syenite, volcanic ash, basalt, and clay units, although the Incesu-Dokuzp inar springs cover most of the drinking and irrigation water demands of this area. The high concentrations of NO 3 and NaCl show that the area around the springs is continuously being contaminated by untreated sewage and agricultural wastes, especially during dry periods. Therefore, this approach is based on the vulnerability studies of the catchment area, determination of the transfer time of the pollutant, and the water-bearing formations of Incesu-Dokuzp inar springs. Vulnerability in this study is defined as the intrinsic hydrogeochemical characteristics of an aquifer, which may show the sensitivity of groundwater to be contaminated by different human activities.  相似文献   

13.
Early Cenozoic magmatism in the eastern Sakarya Zone (NE Turkey) provides an important constraint on the regional tectono-magmatic evolution of the region. Early Eocene syn-collisional adakitic rocks are observed as small stocks with outcropping areas commonly less than 10 km2. This study presents petrography, whole-rock geochemistry and Sr-Nd-Pb isotope data, as well as in-situ 40Ar/39Ar age constraints on one of these adakitic andesites in the Altınpınar area of Gümüşhane, and discusses source region, petrological processes and geodynamic setting prevailed during their genesis. Andesites commonly show microlitic porphyric and vitrophyric porphyric textures, and include significant amounts of mafic microgranular enclaves (MMEs). Plagioclase, hornblende, Fe-Ti oxides and minor pyroxene are the main mineral phases. In-situ 40Ar-39Ar amphibole dating constrains the cooling age of andesites into a time span from 52.8 ± 1.3–48.8 ± 1.9 Ma. Andesites are medium to high-K calc-alkaline and display most of the signatures typical of those of the adakites. They are characterized by moderate MgO (1.7–4.1 wt%), low Y (9−14 ppm), Yb (0.9–1.5 ppm), and HREE and high Sr (325−964 ppm) contents, and high Sr/Y (36–76) ratios. 87Sr/86Sr(t) (0.704948−0.705100) and 143Nd/144Nd(t) (0.512588−0.512628) ratios are in the isotopic range of the adakites. All these geochemical and isotopic data suggest that the parental magma of adakitic andesites has been produced by partial melting of oceanic basalts under amphibole-eclogite facies conditions during the breakoff of the northern Neotethyan oceanic slab.  相似文献   

14.
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15.
Water pollution is a widespread problem in different areas of the world. Some of these problems originated from point contamination sources and widespread contaminant outlet sources which are observed in every country. The major elements and chemical loads of surface water have been dominated by constituents derived directly or indirectly from human activities and/or industrial practices that have increased additives in the last several decades. The point sources of contamination may result from the direct wastewater discharges to the dam sites, which are considered to be the most commonly encountered water pollution problems. One of these problems is the eutrophication process which usually occurs in the static water mass of lakes and other surface water reservoirs. This process may be caused by the continuous increase of nitrogen and phosphorus contents and decrease of O2 level in water causing an anaerobic condition which may stimulate algae-growth flow in these water bodies, consequently reducing the quality of water. Of course, there are many research methods for determining the various kinds of water pollution. In this research, the hydrochemical parameters were evaluated to estimate the types of pollution sources, the level of pollution, and its environmental impacts on the Tahtal dam reservoir.  相似文献   

16.
Lake Seyfe is located in a closed basin near K?r?ehir in the central Anatolian region, Turkey. The aim of this study is to evaluate the groundwater quality and effects of lithogenic contamination carried out in the Lake Seyfe basin, which is represented by various lithologies and groundwater types. Seyfe, Horla and Akp?nar springs are recharged through marbles at the western and southwestern of the basin are ultimately and discharged into the K?z?l?rmak Formation and Lake Seyfe. The waters of deep wells drilled into the marbles are of bicarbonate type (type I) in the Ca2+–Mg2+–HCO3 ? and Ca2+–HCO3 ? facies. Özlühüyük spring and waters from most of trenches and shallow wells, which are fed by the K?z?l?rmak Formation, have a mixed (type II) composition in the Ca2+–Mg2+–HCO3 ?–Cl? facies. Groundwater in the alluvium and K?z?l?rmak Formation along Lake Seyfe has a salty (type III) character in the Na+–Cl? facies. The main reasons of formation and change of the groundwater salinity and hydrochemical facies in the Seyfe basin are causing the various (a) lithogenic pollution and heterogeneity of the K?z?l?rmak Formation, (b) salinity of the upper soil zones, and (c) evaporation of the trench and channel waters open to the atmosphere. Considering parameters such as sodium hazard, specific conductivity, bicarbonate and carbonate hazards, waters in the study area are generally suitable for agricultural usage.  相似文献   

17.
The Pohrenk fluorite mineralisation which makes up Central Anatolia’s most extensive fluorite region is Lutetian aged, and hosted in carbonate rocks that have undergone occasional karstification and silicification along a N–S fault trend. Fluid inclusion values and the position of fluorites in the Tb/La–Tb/Ca diagram show that mineralisation occurred in a hydrothermal environment with homogenisation temperatures ranging from 78.1–363°C. The presence of fluorite as a space filler in carbonate rocks and its association with silicification indicates that the solutions contained considerable amounts of Si alongside F (fluorine). The Pohrenk fluorite samples have 143Nd/144Nd values of between 0.512349 and 0.512497, whilst 87Sr/86Sr values vary between 0.708161 and 0.708772. These values indicate a mantle origin where continental contamination could occur. When the Nd–Sr values are compared to magmatic and young volcanics, the Pohrenk fluorites are seen to be enriched and exhibit similar isotopic signatures to Upper Cretaceous aged magmatics, Early-Middle Miocene volcanics and Mio-Quaternary volcanics.  相似文献   

18.
The present work utilizes in situ gamma ray spectrometric measurement data to map the surface geology of Sar?han Granitoid and its surrounding area. The study area comprises three different lithological units, namely, Hozbirikyayla Formation (limestone and sandy limestones), Sar?han Granitoid (consist of quartz monzodiorite, granodiorite and quartz diorite) and the Ophiolitic olistostromal melange (andesite, basalt, sandstone, gravelly sandstone). When lithological units are assessed according to the radioactivity characteristics, natural radionuclide contents (40K and radionuclides from 238U and 232Th series) of Hozbirikyayla limestones and ophiolitic melange rocks are lower than the Sar?han pluton. The U, Th and K radionuclide contents were found to be 0.8–5.4 ppm, 10.1–33.6 ppm and 1.29–4.41% in the Sar?han plutonic area and 0.9–5.3 ppm, 1.1–20.3 ppm and 0.04–2.71% in Horzbirikyayla formation, respectively. The element concentrations of 238U, 232Th and 40K of the Ophiolitic melange are 1.1–4.5 ppm, 1.6–25.3 ppm and 0.09–3.63%, respectively. Radioelement ratio maps are created for the studied area, because the parameters of radioelement ratios, eU/eTh, eU/K and eTh/K, reflect the radioactive characters of the rock and soil. The Hozbirikyayla Formation is characterized by the highest value of eU/eTh and lowest value of eTh/K. While the lowest eU/eTh and eU/K ratios were observed in the Sar?han Granodiorite, the highest value of eU/K and eTh/K were obtained in the Ophiolitic olistostromal melange. By comparing these maps with the geology, it was found that the radioelement concentrations are in good agreement with the geological properties of the region. In addition to this, the radiation hazard parameters were evaluated to assess the radiation hazard for people living in this area. It has also been found that there is no significant radiologic hazard for humans and the environment in and around studied area.  相似文献   

19.
Geographical information systems (GIS)-based soil erosion risk assessment models continue to play an important role in soil conservation planning. In the present study, soil erosion risk of Istanbul–Elmalı dam watershed was determined within GIS-based COoRdination of INformation on the Environment (CORINE) soil erosion risk assessment method. Initially soil texture, soil depth, and surface stoniness maps were created and were intersected in GIS environment in order to generating erodibility map. Then, Fournier precipitation and Bagnouls–Gaussen drought indices determined based on meteorological data and erosivity were calculated. The composed erodibility map was co-evaluated within erosivity value and slope map of the site for composing potential erosion risk map. At the final step, the previous yearly land use maps which belong to years 1984, 1992, and 2003 intersected with potential erosion risk maps and temporal actual erosion risk alteration were assessed. In conclusion, according to our results in Elmalı watershed dam in 1984 there have been low, medium, and high erosion risks at rates 29.67, 52.49, and 17.84%, respectively, whereas in 2003 the erosion risk values have changed from low to high as 26.43, 46.57, and 27.00%, respectively. Inter-year comparison alteration to the advantage of the high erosion risk could have resulted from over degradation and high exposure to anthropogenic activities.  相似文献   

20.
The number of sinkholes (locally known as obruks) has increased rapidly in recent years near Karap?nar, located in the semi-arid Konya Closed Basin in Central Anatolia. Nineteen sinkholes have formed in the last 33 years (1977–2009) as a result of the collapse of cavity roofs in the Neogene lacustrine limestone in the Obruk Plateau and beneath Quaternary lake sediments in the Karap?nar-Hotam?? Plain. Of these, 13 have formed within the past 4 years (2006–2009). The Obruk Plateau takes its name from the presence of several hundred paleo-sinkholes which formed as a result of natural processes during the Quaternary period. More recently, human activity has induced the formation of new sinkholes, which presents a hazard to life and property. Changing agricultural patterns have led to the opening of thousands of deep wells in recent years, and increased water pumping currently exceeds the sustainable yield of the aquifer. Thus the formation of sinkholes has been triggered by a combination of natural and human causes. The groundwater level has dropped almost 24 m in the vicinity of Karap?nar during the last 26 years (1983–2008). Approximately 8 m of this drop occurred within the 4 years prior to the study (2005–2008). Legally-binding precautions must be taken to prevent further water table decline, in order to decrease sinkhole formation within the basin in the years to come.  相似文献   

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