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N. Kazancı S. A. G. Leroy S. Öncel Ö. İleri Ö. Toprak P. Costa S. Sayılı C. Turgut M. Kibar 《Journal of Paleolimnology》2010,43(1):89-110
Freshwater Lake Ulubat (z
mean = 1.5–2.0 m and Area = ~138 km2), NW Anatolia, Turkey was filled in by fine-to-medium-grain silts during the late Holocene. Deposition in Lake Ulubat has
been 1.6 cm year−1 for the last 50 years, but the sedimentation rate over the last ~1,600 years was lower (0.37 mm year−1). The organic matter and carbonate contents of the infill show cyclic changes that reflect environmental fluctuations. The
silt-dominated lithology and the vertically uniform heavy metal distributions are probably due to wind-controlled sedimentation
in the lake. Heterogeneous mud, derived from a large, mountainous drainage basin, is deposited in the lake mostly during summer,
June to October, when conditions are hot and calm. Winter months are stormier and sediments are re-suspended due to the shallow
water depth and the effect of waves on the lake bottom. It is likely that re-suspended sediments, particularly fine-grained
particles, together with the heavy metals, are transported out of the lake via the outlet, especially during periods of high
lake level. This resuspension and removal process probably caused the lake sediments to become silt-dominated and depleted
in heavy metals. The role of broad shallow lakes in sequestering sediments and heavy metals can be described more accurately
when wind data are considered. Such information may also be helpful for land-use planning in downstream areas. 相似文献
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Most types of coal in Turkey are generally low in rank: lignite, and subbituminous. Most of the coal was formed during the Miocene, Eocene, and Pliocene ages. There are only a few thin Jurassic-age coal occurrences in Turkey. Pennsylvanian age bituminous coal is found on the Black Sea coast. General implications of the petrographic properties of Turkey's coal seams and coal deposits have not yet been taken into consideration comparatively or as a whole.For this study, about 190 channel samples were collected from different locales. The composite profile samples of the seams were taken into considerations. The content and depositional properties as well as some chemical and physical properties of the main coal seams are compared. All coal samples tend to have similar coal petrographic properties and were deposited in intermontane lacustrine basins. Later, they were affected by faulting and post-depositional volcanic activity. As a result, there are variations in the properties and rank of the coal samples. The most abundant coal maceral group is huminite and the most abundant maceral is gelinite. The liptinite and inertinite contents of the coal are low and the maceral contents of the coals show great similarity. The depositional environments of the all coals are lacustrine dominated. 相似文献
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Deformability of rock masses influencing their behavior is an important geomechanical property for the design of rock structures. Due to the difficulties in determining the deformability of jointed rock masses at the laboratory-scale, various in-situ test methods such as pressuremeter, dilatometer, plate loading tests etc. have been developed. Although these techniques are currently the best and direct methods, they are time-consuming and expensive, and present operational difficulties. In addition, the influence of the test volume on deformation modulus depending on the method employed is also important. For these reasons empirical equations to indirectly estimate the deformation modulus have also been recommended by several investigators as an alternative approach. In this study; the geomechanical quality of weak, heavily jointed, sheared and/or blocky greywacke rock masses, on which very concentrated civil works are continuing at the southern and southwestern parts of Ankara (Turkey), was assessed. The deformation modulus was determined by pressuremeter tests, the possible effects of variables on the derived deformation modulus from the pressuremeter test were evaluated by numerical methods, and the comparisons between the deformation modulus of the greywackes obtained from the pressuremeter tests and their geomechanical quality (GSI and RMR) were made. Numerical simulations revealed that the presence of a disturbed annulus around the borehole causes underestimation of the deformation modulus, while the effect of length to diameter ratio of the pressuremeter probe on the deformation modulus is minor. Based on the geo-engineering characterization assessments, mainly two greywacke rock masses with different geomechanical qualities were identified. Geotechnical quality of one of these rock masses was verified by the back analysis of two slope failures. The empirical equations to indirectly estimate the deformation modulus of the greywackes using their GSI and RMR values yielded high coefficients of correlation. 相似文献
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The distribution of polygenetic and monogenetic volcanoes of the Neogene-Quaternary Cappadocian Volcanic Province (CVP) is analyzed to investigate the relationship between vent location and regional tectonic lineaments. Two fault systems exist in the province. One system (Miocene-Quaternary Tuzgölü–Ecemiş system) is oblique, whereas the other system (late Miocene–Pliocene CVP system) is parallel to the long axis of the CVP. The polygenetic volcanoes are aligned parallel to the second system but concentrate around the major faults of the first system. Regional offsets are proposed along the first fault system based on the distribution of the polygenetic volcanoes. The monogenetic volcanoes group into five geographically distinct clusters. In the western part of the CVP, the monogenetic cones are aligned parallel to the CVP system, whereas in the central part the cones are fed by dikes injected along the recent fractures of the Tuzgölü–Ecemiş system. In the eastern part, the monogenetic cones form along the radial fractures of the Erciyes composite volcano. 相似文献
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