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11.
Gültekin Topuz Rainer Altherr Winfried H. Schwarz Abdurrahman Dokuz Hans-Peter Meyer 《International Journal of Earth Sciences》2007,96(5):861-873
The Kurtoğlu metamorphic complex, that forms part of the pre-Liassic basement of the Sakarya zone in northern Turkey, consists
of at least two tectonic units. Blueschist-facies rocks of unknown metamorphic age in the southern part of the complex are
tectonically overlain by Variscan low-pressure high-temperature metamorphic rocks. The latter comprise mica schists and fine-grained
gneisses, cut by metaleucogranitic dikes, as well as migmatitic biotite gneisses and subordinate amphibolite intercalations.
Structural data indicate that metamorphism and penetrative deformation occurred after dyke intrusion. Peak metamorphic conditions
of the mica schists, fine-grained gneisses and metaleucogranites are estimated to ∼650°C and ∼0.4 GPa, based on phase relationships
in the system NCKFMASH, Fe–Mg partitioning between garnet and biotite as well as garnet-aluminosilicate-quartz-plagioclase
(GASP) and garnet-plagioclase-biotite-quartz (GBPQ) barometry. Peak temperatures of the migmatitic biotite gneisses and amphibolite
intercalations are not well constrained but might have been significantly higher (690–740°C), as suggested from hornblende-plagioclase
thermometry. 40Ar–39Ar incremental dating on muscovite and biotite fractions from the mica schists and fine-grained gneisses yielded plateau ages
of ∼323 Ma. Significantly older model ages of ∼329 and ∼337 Ma were obtained on muscovite fractions from two metaleucogranite
samples. These fractions contain both relict igneous and newly formed metamorphic muscovite. 相似文献
12.
Gültekin?TopuzEmail author Rainer?Altherr Winfried?H.?Schwarz Wolfgang?Siebel Muharrem?Sat?r Abdurrahman?Dokuz 《Contributions to Mineralogy and Petrology》2005,150(4):441-455
The post-collisional Saraycık granodiorite intruded into a late Paleocene to early Eocene nappe pile that formed during collision of the Pontides in the North and the Anatolide-Tauride platform in the South, leading to the formation of the İzmir-Ankara-Erzincan suture. A relatively shallow pluton intrusion depth (∼5 to 8 km) was estimated from Al-in-hornblende geobarometry and contact metamorphic assemblages. The emplacement age is tightly constrained to ∼52 Ma by two Ar–Ar plateau and total fusion ages on biotite. The main mass of the pluton consists of metaluminous to peraluminous biotite granodiorite and hornblende-biotite granodiorite. In addition, up to 10-m thick dacitic and <25-cm thick aplitic dikes occur. Granodiorites and dacites show many close compositional similarities to high-silica adakites from supra-subduction zone settings, but tend to be slightly more felsic and to have a higher aluminium saturation index. Chondrite-normalized (cn) rare earth element patterns are characterized by high ratios of (La/Yb)cn, concave-upward shapes of the HREE and a lack of significant Eu anomalies. In conjunction with relatively high abundances of Ba and Sr as well as low abundances of Y, HREE and Sc, these patterns suggest a feldspar-poor, garnet ± amphibole-rich fractionating mineral assemblage (residue). All samples have very similar Nd–Sr isotopic characteristics, regardless of rock type. Initial εNd values range from −0.3 to −1.2 and initial 87Sr/86Sr ratios from 0.70491 to 0.70529. It is suggested that the magmas formed by partial melting of mafic lower crust at elevated pressures (∼1 to 2 GPa). 相似文献
13.
Sinan?YatkinEmail author Mutlu?Adali Abdurrahman?Bayram 《Journal of Atmospheric Chemistry》2016,73(3):241-259
The chemistry of rainwater was studied in three sites of a metropolitan city of Turkey to determine the spatial variation, sources affecting composition and the extent of their influence. The acidity of rainwater, Ca, Co, Cr, Zn, Ba, V and Ni showed significant spatial variations. The most of measured species were moderately to extremely enriched compared to the local soil, which is likely arisen from the anthropogenic activities. SO4 2?, K and Ca were found to be predominantly non-sea origin. Two receptor models, Positive Matrix Factorization (PMF) and Chemical Mass Balance (CMB), agreed well on the source contribution estimations of Al, K, Zn, V, Pb and Cr. The PMF and CMB resolved very similar source contribution profiles to the elemental concentrations of Ca, Zn, V, Pb, K and Na, which the majority of those resulted from mineral industries, bell casting+steel industries, fossil fuel burning, biomass burning+sea salt and sea salt, respectively. The PMF resolved the source contributions of long-transported emissions, particularly for Ba, Sr and Mn, which could not be estimated by the CMB. 相似文献
14.
Firat Aydin Abdurrahman Saydut Beniz Gunduz Isil Aydin Candan Hamamci 《洁净——土壤、空气、水》2012,40(4):444-448
Chemical speciation of vanadium is important to understand the true nature of this element in the environment as well as its biochemical pathways. Sample pretreatment, preparation, and chemical speciation methods were applied for vanadium in coal bottom ash here. Two‐stage microwave acid digestion was used to preparation of samples. Determination of vanadium was performed using inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Speciation of vanadium was carried out using a seven‐step sequential extraction procedure of the coal bottom ash each releasing species of vanadium: Water soluble, exchangeable, carbonate, reducible, oxidizable, sulfide, and residual fractions. Total vanadium concentration in the coal bottom ash is 701 mg kg?1 d.w. The most abundant form of vanadium in coal bottom ash is residual fraction of vanadium (196 mg kg?1 d.w.). Relative abundances of the remaining vanadium fractions in coal bottom ash are as follows: Reducible (176 mg kg?1 d.w.) > sulfide (176 mg kg?1 d.w.) > carbonate (85 mg kg?1 d.w.) > oxidizable (50 mg kg?1 d.w.) > water soluble (10.6 mg kg?1 d.w.) > exchangeable (9.0 mg kg?1 d.w.). 相似文献
15.
Quantifying temporal variations in water resources of a vulnerable middle eastern transboundary aquifer system 
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下载免费PDF全文 Freshwater resources in the arid Arabian Peninsula, especially transboundary aquifers shared by Saudi Arabia, Jordan, and Iraq, are of critical environmental and geopolitical significance. Monthly Gravity Recovery and Climate Experiment (GRACE) satellite‐derived gravity field solutions acquired over the expansive Saq transboundary aquifer system were analysed and spatiotemporally correlated with relevant land surface model outputs, remote sensing observations, and field data to quantify temporal variations in regional water resources and to identify the controlling factors affecting these resources. Our results show substantial GRACE‐derived terrestrial water storage (TWS) and groundwater storage (GWS) depletion rates of ?9.05 ± 0.25 mm/year (?4.84 ± 0.13 km3/year) and ?6.52 ± 0.29 mm/year (?3.49 ± 0.15 km3/year), respectively. The rapid decline is attributed to both climatic and anthropogenic factors; observed TWS depletion is partially related to a decline in regional rainfall, while GWS depletions are highly correlated with increasing groundwater extraction for irrigation and observed water level declines in regional supply wells. 相似文献
16.
Abdurrahman Dokuz İbrahim Uysal Wolfgang Siebel Mehmet Turan Robert Duncan Miğraç Akçay 《Contributions to Mineralogy and Petrology》2013,166(5):1443-1468
New geochemical and isotopic data for post-collisional Early Eocene and Late Miocene adakitic rocks from the eastern part of the Sakarya Zone, Turkey, indicate that slab and lower crustal melting, respectively, played key roles in the petrogenesis of these rocks. The Early Eocene Yoncal?k dacite (54.4 Ma) exhibits high Sr/Y and La/Yb ratios, low Y and HREE concentrations, moderate Mg# (44–65), and relatively high εNd and low ISr values, similar to adakites formed by slab melting associated with subduction. Geochemical composition of the Yoncal?k dacite cannot be explained by simple crystal fractionation and/or crustal contamination of andesitic parent magma, but is consistent with the participation of different proportions of melts derived from subducted basalt and sediments. Sr/Y correlates horizontally with Rb/Y, and Pb/Nd correlates vertically with Nd isotopic composition, indicating that Sr and Pb budgets are strongly controlled by melt addition from the subducting slab, whereas positive correlations between Th/Nd and Pb/Nd, and Rb/Y and Nb/Y point to some contribution of sediment melt. In addition to low concentrations of heavy rare earth elements (~2–3 times chondrite), a systematic decrease in their concentrations and Nb/Ta ratios with increasing SiO2 contents suggests that slab partial melting occurred in the garnet stability field and that these elements were mobilized by fluid flux. These geochemical and isotopic signatures are best explained by slab breakoff and fusion shortly after the initiation of collision. Although the Late Micone Tavda?? rhyolite (8.75 Ma) has some geochemical features identical to adakites, such as high Sr/Y and La/Yb ratios, low Y and HREE concentrations, other requirements, such as sodic andesite and/or dacite with relatively high MgO and Mg# (>50), relatively high Ni and Cr, low K2O/Na2O (<0.4), high Sr (>400 ppm), for slab-derived adakites are not provided. It is sodic in composition and shows no traces of fractionation from dacitic parent magma. Low Nd and high Sr isotope ratios suggest derivation by partial fusion of calc-alkaline, juvenile crust with high Sr/Y and La/Yb ratios. 相似文献
17.
Abdurrahman Dokuz Erkan Tanyolu Salim Genç 《International Journal of Earth Sciences》2006,95(3):370-394
The Yusufeli area, in the Eastern Black Sea Region of Turkey, contains a crystalline complex that intruded into the Carboniferous metamorphic basement and is composed of two intrusive bodies: a gabbro-diorite and a tonalite-trondhjemite. The mafic body (45–57 wt% SiO2) displays a broad lithological spectrum ranging from plagioclase-cumulate to quartz diorite. Primitive varieties of the body have Mg-number, MgO and Cr contents that are close to those expected for partial melts from mantle peridotite. Data are consistent with the magma generation in an underlying mantle wedge that was depleted in Zr, Nb and Ti, and enriched in large ion lithophile elements (K, Rb, Ba, Th). However, high Al2O3, CaO and generally low Ni (<65 ppm) contents are not in agreement with the unfractionated mantle-derived primitive magmas and require some Al2O3- and CaO-poor mafic phases, in particular, olivine and orthopyroxene. Absence of orthopyroxene in crystallization sequence, uralitization, and a common appearance of clinopyroxene surrounded by hornblende imply an anhydrous phase fractionated from highly hydrous (5–6%) parent. Geochemical modelling suggests derivation by 15–20% melting of a depleted-lherzolitic mantle. The tonalite-trondhjemite body (58–76 wt% SiO2) ranges in composition from quartz diorite to granodiorite with a low-K calc-alkaline trend. Although LILE- and LREE- enriched characteristics of the primitive samples imply a metasomatic sub-arc mantle for their source region, low MgO, Ni and Cr concentrations rule out direct derivation from the mantle wedge. Also, lack of negative Eu anomalies suggests an unfractionated magma and precludes a differentiation from the diorites of mafic body, which show negative Eu anomalies. Their Na enrichments relative to Ca and K are similar to those of Archean tonalites, trondhjemites and granodiorites and Cenozoic adakites. However, they exhibit important geochemical differences from them, including low-Al (<15 wt%) contents, unfractionated HREE patterns and evolution towards the higher Y concentrations and lower Sr/Y ratios within the body. All these features are obtained in experimentally produced melts from mafic rocks at low pressures (≤5 kbar) and also widespread in the rocks of arc where old (Upper Cretaceous or older) oceanic crust is being subducted. Major and REE modelling supports formation of the quartz dioritic parent to the felsic intrusive rocks by 70% partial melting of a primitive gabbroic sample (G694). Therefore, once taking into account the extensional conditions prevailing in the Pontian arc crust in Early Jurassic time, former basic products (gabbros) seem to be the most appropriate source for the tonalite-trondhjemite body. Magmatic emplacement of stratigraphically similar lithologies in the Pulur Massif, just southwest of the Yusufeli, was dated to be 184 Ma by the 40Ar/39Ar method on amphibole, and is compatible with the initiation of Early Jurassic rifting in the region. 相似文献