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1.
2.
Huseyin Ozdemir Alper Unal Tayfun Kindap Ufuk Utku Turuncoglu Zeynep Okay Durmusoglu Maudood Khan Mete Tayanc Mehmet Karaca 《Theoretical and Applied Climatology》2012,108(1-2):31-38
The Anatolian Peninsula is located at the confluence of Europe, Asia, and Africa and houses 81 cities of which 79 of them have population over 100,000. We employed some criteria to select the cities from the 81 cities. After accomplishing all the criteria, eight cities were remaining for the study. Nonparametric Mann–Kendall test procedure was employed for the urban and rural stations of these cities to detect the long-term change in temperature trends. Statistical analysis of daily minimum temperatures for the period between 1965 and 2006 suggest that there is no statistically significant increase in rural areas. In contrast to the findings of the previous studies, however, all the urban sites and difference between urban and rural pairs show significant increase in temperatures, a strong indication for the existence of urban heat island (UHI) affect over the region. Regional Climate Model was also utilized to assess the changes in temperature by the end of century for the region. The findings suggest that an increase of up to 5°C is possible. Climate change effects enforced with UHI have the potential to cause serious problems for the entire region and hence needs to be studied thoroughly. 相似文献
3.
Polycyclic aromatic hydrocarbons (PAHs) are important environmental pollutants due to their persistence and bioaccumulation potential both in organisms and in sediments. In this study, bioaccumulation and depuration experiments were performed employing local Mediterranean mussel species, Mytilus galloprovincialis, with two biomarkers: filtration rate and lysosomal stability (neutral red retention) assay. Benzo(a)anthracene (BaA) was chosen as the model PAH compound due to its common presence in several matrices in the marine environment. Bioconcentration Factors (BCFs) for the mussels exposed to different BaA concentrations were calculated from both kinetic rate constants and from the experimental data and found between 27-3184 and 16-2745, respectively. Experimental QSAR values were found comparable to the previous QSAR models created for BaA. The effect of BaA exposure on the mussels showed a more clear dose-response relationship according to the results of lysosomal stability compared to the filtration rate. 相似文献
4.
Enis Morkoc Legovic Tarzan Oya Okay Huseyin Tufekci Vildan Tufekci Leyla Tolun Fatma Karakoc 《Environmental Geology》2007,53(1):103-112
The Izmit Bay is an elongated semi-enclosed bay in the Marmara Sea. It is being increasingly polluted by both domestic and
industrial waste discharge since 1970’s. A monitoring program was conducted between 1999-2000 to document the state of pollution
in the bay. This includes the effect of Marmara (Izmit) earthquake (magnitude 7.4) that occurred in August 1999. A stable
two-layer ecosystem exists in the bay throughout the year due to continuous inflows of the saltier Mediterranean and brackish
Black Sea waters to the Marmara basin. Therefore, the principal biochemical characteristics of the bay are governed by the
two-layer flow system over the basin. Dissolved oxygen (DO) is generally at a saturated levels in the surface layer which
is 10 to 15 m thick, but it is depleted to 60–70 μM in the lower layer, exhibiting a steep gradient in the sharp halocline.
When the earthquake occurred, great loads of industrial wastes were released into the bay surface waters, which enhanced primary
production in the upper layer and thus large export of particulate organic matter to lower layer and eventually to the bottom.
Accordingly, DO was consumed and anoxic condition was established even in the upper layer/halocline interface, the halocline
and bottom waters of the eastern and central bay. In this period, concurrent increases were observed in phosphate and ammonia
contents at the halocline and in deep waters whilst the nitrate was almost consumed via denitrification processes in the anoxic
water. Recently, the industrial C, N and P loads increased by as much as 8 fold within five years (1995–2000) whilst domestic
inputs increased by 50%. Total organic matter discharged to the bay increased more than double within the last 15 years. Besides,
most factories in the region release toxic wastes into the bay after only partial treatment. 相似文献
5.
A. I. Okay 《Journal of Metamorphic Geology》2002,20(8):757-768
Sodic metapelites with jadeite, chloritoid, glaucophane and lawsonite form a coherent regional metamorphic sequence, several tens of square kilometres in size, and over a kilometre thick, in the Orhaneli region of northwest Turkey. The low‐variance mineral assemblage in the sodic metapelites is quartz + phengite + jadeite + glaucophane + chloritoid + lawsonite. The associated metabasites are characterized by sodic amphibole + lawsonite ± garnet paragenesis. The stable coexistence of jadeite + chloritoid + glaucophane + lawsonite, not reported before, indicates metamorphic pressures of 24 ± 3 kbar and temperatures of 430 ± 30 °C for the peak blueschist facies conditions. These P–T conditions correspond to a geotherm of 5 °C km?1, one of the lowest recorded in continental crustal rocks. The low geotherm, and the known rate of convergence during the Cretaceous subduction suggest low shear stresses at the top of the downgoing continental slab. 相似文献
6.
Gültekin Topuz Aral I. Okay Rainer Altherr Winfried H. Schwarz Gürsel Sunal Lütfi Altınkaynak 《Island Arc》2014,23(3):181-205
Within the Tethyan realm, data for the subduction history of the Permo–Triassic Tethys in the form of accretionary complexes are scarce, coming mainly from northwest Turkey and Tibet. Herein we present field geological, petrological and geochronological data on a Triassic accretionary complex, the A?vanis metamorphic rocks, from northeast Turkey. The A?vanis metamorphic rocks form a SSE–NNW trending lozenge‐shaped horst, ~20 km long and ~6 km across, bounded by the strands of the active North Anatolian Fault close to the collision zone between the Eastern Pontides and the Menderes–Taurus Block. The rocks consist mainly of greenschist‐ to epidote‐amphibolite‐facies metabasite, phyllite, marble and minor metachert and serpentinite, interpreted as a metamorphic accretionary complex based on the oceanic rock types and ocean island basaltic, mid‐ocean ridge basaltic and island‐arc tholeiitic affinities of the metabasites. This rock assemblage was intruded by stocks and dikes of Early Eocene quartz diorite, leucogranodiorite and dacite porphyry. Metamorphic conditions are estimated to be 470–540°C and ~0.60–0.90 GPa. Stepwise 40Ar/39Ar dating of phengite–muscovite separates sampled outside the contact metamorphic aureoles yielded steadily increasing age spectra with the highest incremental stage corresponding to age values ranging from ~180 to 209 Ma, suggesting that the metamorphism occurred at ≥ 209 Ma. Thus, the A?vanis metamorphic rocks represent the vestiges of the Late Triassic or slightly older subduction in northeast Turkey. Estimated P–T conditions indicate higher temperatures than those predicted by steady state thermal models for average subduction zones, and can best be accounted for by a hot subduction zone, similar to the present‐day Cascadia. Contact metamorphic mineral assemblages around an Early Eocene quartz diorite stock, on the other hand, suggest that the present‐day erosion level was at depths of ~14 km during the Early Eocene, indicative of reburial of the metamorphic rocks. Partial disturbance of white‐mica Ar–Ar age spectra was probably caused by the reburial coupled with heat input by igneous activity, which is probably related to thrusting due to the continental collision between Eastern Pontides and the Menderes–Taurus Block. 相似文献
7.
A. I. Okay 《Contributions to Mineralogy and Petrology》1982,79(4):361-367
Volcano-sedimentary rocks in an imbricate tectonic zone around a peridotite massif have been studied northeast of the town of Tavanli in Northwest Turkey. Basic volcanic rocks, which are the dominant rock type in this zone, show incipient blueschist metamorphism and associated metasomatism. While the igneous textures of the volcanic rocks are retained, augites are partially to completely replaced by sodic pyroxene, and plagioclase is albitised resulting in rocks with 6–8 wt.% Na2O. The volcanic rocks are cross-cut by numerous veins of calcite, aragonite, quartz, pumpellyite, albite, lawsonite and sodic pyroxene. Pelagic limestones, which are interbedded with the basic volcanic rocks, consist of coarse aragonite grains showing partial replacement by calcite. The occurrence of aragonite, lawsonite and albite indicates conditions of metamorphism for the whole zone in the range of 5–8 kb and 150–200° C. Metasomatism, probably related to high pressure serpentinization, has occurred contemporaneously with the incipient high pressure metamorphism. 相似文献
8.
Sarah Sherlock Simon Kelley Simon Inger Nigel Harris Aral Okay 《Contributions to Mineralogy and Petrology》1999,137(1-2):46-58
Geochronological investigations in high- and ultra-high-pressure metamorphic rocks are problematic since firstly the low
temperatures lead to fine grain size and disequilibrium assemblages, and secondly the problem of “excess argon” affects 40Ar-39Ar systematics, the most commonly used isotopic system. The Tavsanli Zone is a belt of high-pressure low-temperature (HP-LT) rocks spanning NW Turkey and is one such region where previous geochronological studies have produced a range of estimates
for the age of HP-LT metamorphism, raising the question of whether they are geologically significant. This study presents new data from the Tavsanli
Zone; 40Ar-39Ar ages are in the range 60 Ma to 175 Ma, whilst Rb-Sr ages are restricted to 79.7 Ma to 82.8 Ma, confirming the presence
of excess argon. Detailed ultra-violet laser ablation microprobe (UVLAMP) studies have revealed younger 40Ar-39Ar ages in the cores of coarser white micas, which in conjunction with 40Ar-39Ar ages from the finest grained lithologies and the Rb-Sr white mica crystallisation ages, constrain the post-HP-LT metamorphism exhumation rates of these rocks. Petrological and regional constraints suggest that syn-subduction exhumation
and cooling took place initially by synchronous subduction and exhumation by underplating. This is followed by a phase of
syn-continent-continent collision at a rate of approximately 1.5 mma−1 and exhumation to the surface via thrusting. The 40Ar-39Ar hornblende data from a granodiorite intruding the HP-LT rocks constrain the later parts of exhumation path. This study highlights the importance of a multi-system geochronological
approach when attempting to determine the history of HP-LT rocks.
Received: 12 May 1998 / Accepted: 21 April 1999 相似文献
9.
A. I. Okay 《Contributions to Mineralogy and Petrology》1978,68(1):7-11
The compositions of sodic pyroxenes from blueschist metabasites in Northwest Turkey were investigated by electronprobe microanalysis. These are compared with sodic pyroxenes from high-grade blueschist terrains and eclogites with special reference to the island of Syros in Greece. Pyroxenes from lawsonite zone metabasites in Northwest Turkey are chloromelanites, aegerine augites and aegerine jadeites with the acmite contents ranging from 65% down to 30%. Epidote-garnet bearing high-grade blueschist metabasites of Syros on the other hand contain omphacite with the acmite content less than 30%. All the analyzed sodic pyroxenes from eclogites and high-grade blueschists in the literature are also omphacites with low acmite contents. It is argued that the acmite content of the sodic pyroxene decreases with rising temperature of metamorphism. This is almost entirely related to the appearance of epidote as an additional ferric ion bearing phase with an increase in temperature. 相似文献
10.
The Triassic succession of Bjørnøya (200 m) comprises the Lower Triassic Urd Formation (65 m) of the Sassendalen Group, and the Middle and Upper Triassic Skuld Formation (135 m) of the Kapp Toscana Group. These units are separated by a condensed '.'Middle Triassic sequence represented by a phosphatic remainé conglomerate (0.2m).
The Urd Formation consists of grey to dark grey shales with yellow weathering dolomitic beds and nodules. Palynology indicates the oldest beds to be Diencrian; ammonoid faunas in the middle and upper part of the formation arc of Smithian age. The organic content (c. 1 %) includes kerogen of land and marine origin, reflecting a shallow marine depositional environment.
The Skuld Formation is dominated by grey shales with red weathering siderite nodules. There are minor coarsening upwards sequences; the highest bed exposed is a 20 m thick, very fine-grained sandstone. Palynomorphs indicate a late Ladinian age for the lower part of the formation, and macrofossils and palynomorphs indicate Ladinian to Carnian ages for the upper part. Sedimentary structures, a sparse marine fauna and microplankton indicate deposition in a shallow marine environment. The organic residues contain dominantly terrestrially derived kerogen. 相似文献
The Urd Formation consists of grey to dark grey shales with yellow weathering dolomitic beds and nodules. Palynology indicates the oldest beds to be Diencrian; ammonoid faunas in the middle and upper part of the formation arc of Smithian age. The organic content (c. 1 %) includes kerogen of land and marine origin, reflecting a shallow marine depositional environment.
The Skuld Formation is dominated by grey shales with red weathering siderite nodules. There are minor coarsening upwards sequences; the highest bed exposed is a 20 m thick, very fine-grained sandstone. Palynomorphs indicate a late Ladinian age for the lower part of the formation, and macrofossils and palynomorphs indicate Ladinian to Carnian ages for the upper part. Sedimentary structures, a sparse marine fauna and microplankton indicate deposition in a shallow marine environment. The organic residues contain dominantly terrestrially derived kerogen. 相似文献