Yazarlar
- Kaygusuz, Abdullah(24)
- Yücel, Cem(15)
- Arslan, Mehmet(14)
- Maden, Nafiz(8)
- Siebel, Wolfgang(8)
- Aydinçakir, Emre(7)
- Aydınçakır, Emre(7)
- Dokuz, Abdurrahman(7)
- Kandemir, Raif(7)
- Aydin, Faruk(6)
- Eyuboglu, Yener(6)
- Karsli, Orhan(6)
- Şen, Cüneyt(6)
- Akaryali, Enver(5)
- Ruffet, Gilles(5)
- Sipahi, Ferkan(5)
- Temizel, Irfan(5)
- Temizel, İrfan(5)
- Ilbeyli, Nurdane(4)
- Jeong, Youn-Joong(4)
- Santosh, M.(4)
- Akaryalı, Enver(3)
- Bektas, Osman(3)
- Bektaş, Osman(3)
- Chen, Bin(3)
- Chung, Sun-Lin(3)
- Dudas, Francis O.(3)
- Eyüboǧlu, Yener(3)
- Gücer, Mehmet Ali(3)
- Güloğlu, Zikrullah Samet(3)
- Uysal, Ibrahim(3)
- Yi, Keewook(3)
- Abdioğlu, Emel(2)
- Aslan, Zafer(2)
- Aydin, F.(2)
- Eker, Cigdem Saydam(2)
- Karsli, O.(2)
- Korkmaz, Sadettin(2)
- Sadiklar, M. Burhan(2)
- Sadiklar, M.B.(2)
Yayınlar
- Yüksek Lisans TeziAçık Erişim2026Gölönü plütonu’nun (Kürtün-Gümüşhane) petrografisi ve mineral kimyası
Sefa Güzeldal
Doğu Pontidler, farklı yaş ve bileşime sahip çok sayıda plütonik kayaç topluluğunu barındırmaktadır. Gümüşhane’nin Kürtün ilçesinde yer alan Orta Eosen yaşlı Gölönü Plütonu, kendine özgü petrografik ve jeokimyasal özellikleriyle dikkat çekmektedir. Bu çalışmada, plütona ait kayaçların petrografik özellikleri ve mineral kimyası verileri birlikte değerlendirilerek magmanın kristalleşme ve yerleşim süreçlerine ait fizikokimyasal parametrelerin (sıcaklık, basınç ve oksijen fugasitesi) belirlenmesi amaçlanmıştır. Ayrıca, mineral kimyası temelli yaklaşımlarla kristalleşme koşulları nicel olarak değerlendirilmiştir. Plüton yaklaşık 14 km2’lik bir alan kaplamakta olup KD-GB doğrultulu bir uzanım sergilemektedir. Modal mineralojik veriler, kayaçların granodiyorit ve granit bileşiminde olduğunu göstermektedir. Dokusal özellikler ince ve orta taneli yapılarla birlikte yer yer porfirik, poikilitik ve grafik dokuların geliştiğini ortaya koymaktadır. Kayaçların başlıca mineral bileşenleri plajiyoklaz, K-feldispat, kuvars, amfibol, biyotit ve Fe-Ti oksitlerinden oluşurken, zirkon, apatit, sfen ve allanit aksesuar mineraller olarak bulunmaktadır. Plajiyoklazlar oligoklas-labradorit aralığında (An0.1–56), K-feldispatlar ise ortoklaz bileşimindedir. Amfiboller kalsik amfibol grubuna ait olup magnezyoamfibol (Mg# = 0,78–0,85) bileşimi sunmaktadır. Amfibol ve plajiyoklaz mineral kimyasına dayalı hesaplamalar kristalleşme sıcaklıklarının 751–904 °C arasında değiştiğini göstermektedir. Jeobarometrik hesaplamalar 0,67–2,23 kbar basınç değerleri ve yaklaşık 3–7 km yerleşim derinliğine işaret etmektedir. Oksijen fugasitesi değerleri yaklaşık −13,0 ile −10,6 log birimi arasında değişirken, magma su içeriği %3,3–5,0 olarak hesaplanmıştır. Elde edilen veriler, Gölönü Plütonu’nun sığ kabuksal seviyelerde yerleşmiş, suca zengin ve çok evreli magmatik evrim süreçlerinden geçmiş bir magmatik sistemin ürünü olduğunu göstermektedir.
- MakaleAçık Erişim2026GEOLOGY AND MINERAL CHEMISTRY OF THE ARSLANDEDE PLUTON IN THE EASTERN PONTIDES
Güloğlu, Zikrullah Samet; Kaygusuz, Abdullah
The Middle Eocene Arslandede Pluton, exposed in the Bayburt region on the southern margin of the Eastern Pontides (NE Turkey), has been investigated in terms of its geology and mineral chemistry. The pluton exhibits a NW-SE elongation and covers an area of approximately 7 km². It comprises a broad compositional spectrum ranging from monzodiorite to quartz monzonite. Major rock-forming minerals include plagioclase (An25-48), orthoclase (Or69-88), quartz, amphibole (Mg# = 0.63-0.73), biotite (Mg# = 0.52-0.62), pyroxene (Mg# = 0.70-0.75), and Fe-Ti oxides. Crystallization conditions, estimated via amphibole-plagioclase thermometry and Al-in-hornblende barometry, suggest crystallization temperatures of 737-812 °C and pressures of 0.09-1.61 kbar, corresponding to depths of 0.3-6.0 km. These results indicate that the pluton was emplaced at shallow crustal levels and subsequently solidified under low-pressure conditions. Comparison with other Middle Eocene plutons in the region reveals similar crystallization conditions, suggesting a common tectonic setting during the post-collisional extensional regime in the Eastern Pontides.
- MakaleAçık Erişim2026Detrital zircon ages, Lu-Hf isotopes of zircon grains, Sr-Nd isotopes on whole rock and geochemistry of Campanian turbidites in the Eastern Pontides (NE Türkiye): A provenance assessment and Gondwana records
Eker, Çiğdem Saydam; Yücel, Cem; Kaygusuz, Abdullah; Aydınçakır, Emre; Jeong, Youn-Joong; Yılmazer, Sinan; Sünnetçi, Kadir
Detrital zircons are crucial stand-ins for the history of continental crust growth and disintegration, as well as the dispersal and assembly of supercontinents. Detrital zircons are effectively used to assess crustal history because sediments transport zircons from source rocks that are no longer at the surface. This study presents detailed Lu-Hf isotopic, U-Pb geochronological analyses of zircon, Sr-Nd isotopic analyses and whole-rock geochemical results from sandstone, volcanically derived sandstone and tuff samples of the Campanian-aged Bozbent Member in the Eastern Pontide Orogen belt of the Sakarya Zone. Sedimentological analyses show that the Bozbent Member was transported and deposited by turbidite currents, while petrographic and geochemical analyses show that the sandstones range from greywacke to litharenite. In this study, U-Pb ages of detrital zircon obtained from Campanian sandstones are presented, along with in situ εHf data. A magmatic origin is indicated by the majority of zircons' oscillatory zoning and by Th/U ratios ranging from 0.2 to 1.5. The ages of detrital zircons range from 2819 to 78 Ma, with most of these zircons being Proterozoic (552–994 Ma). Proterozoic zircons are detrital zircons associated with the Gondwana and the African Craton. The whole-rock geochemical data and Sr-Nd isotope compositions of the sandstones are consistent with local Carboniferous felsic plutons, Jurassic mafic and felsic plutons, Jurassic volcanic rocks, Jurassic clastic rocks and clastic material from Precambrian recycled sediments. It was calculated that more than 90% of the detrital zircons had crystallisation ages older than their depositional ages (CA-DA > 150 Ma, indicative of an extensional basin model). These findings indicate that the Campanian-aged Bozbent Member turbiditic sequence in the Eastern Pontides was deposited in an extensional fore-arc basin and therefore exhibits the petrographic and geochemical characteristics of passive margin sandstones.
- MakaleYalnız künye2025Mantle genesis and crustal contamination in Carboniferous granitoids using U-Th-K concentrations at the Akşar Pluton in the Eastern Pontides, NE Türkiye
Maden, Nafız; Gücer, Mehmet Ali; Akaryalı, Enver
New radiogenic heat production (RHP) data are presented for Carboniferous granites outcropping in the Akşar region (Bayburt, NE Turkey) to contribute to ongoing debates on the genetic and lithologic relationship between the Akşar and Gümüşhane plutons, which is the most widely distributed granitic rocks in the region. The scope of this study consists of rocks composed of enriched mantle material metasomatized by fluids from the previously subducted plate. We observed average K value for the Akşar Pluton was found to be 3.09 ± 1.58 %. Additionally, average Th/U and U/Th values of 3.95 ± 1.37 and 0.29 ± 0.10, respectively. The calculated RHP value for the Akşar Pluton was 2.20 ± 0.56 μWm−3. Numerical results suggest that the Carboniferous Akşar pluton's primary magma was the product of mixing lithospheric mantle and mid-to-lower crustal melts because of partial melting, differentiation, and emplacement in the shallow continental magma chamber. The geochemical and petrogenetic characteristics of the Akşar region magmas suggest that crustal contamination occurred at multiple levels, particularly within the lower to middle crust of the plutonic core complex. This complex likely retains geochemical signatures indicative of subducted Paleotethys oceanic lithosphere. These findings provide critical insights into the magmatic evolution of the Eastern Pontides, contributing to a more comprehensive understanding of crust–mantle interactions and the broader geodynamic framework of northeastern Türkiye.
- MakaleAçık Erişim2024U–Pb zircon dating, Sr-Nd whole-rock and Lu-Hf zircon isotope analyses of the Eocene Arslandede pluton, Eastern Pontides, NE Turkey: Implications for mantle source and magma evolution
Kaygusuz, Abdullah; Güloğlu, Zikrullah Samet; Aydınçakır, Emre; Yücel, Cem; Vural, Alaaddin; Siebel, Wolfgang; Jeong, Youn-Joong
The Eastern Pontide Orogenic Belt (EPOB) hosts numerous plutonic bodies with different dimensions, compositions and ages ranging from Paleozoic to Late Eocene in NE Turkey. U-Pb zircon dating suggests that the Arslandede pluton crystallized at 44.50 ± 0.29 Ma, corresponding to the Lutetian (Middle Eocene) period. Rocks of this pluton have monzonitic character, with compositions ranging from monzodiorite to granite (SiO2 = 49˗71 wt%). The studied monzonitic rocks have I-type, metaluminous and shoshonitic character and are enriched in large-ion lithophile elements (LILEs). The rare earth elements (REEs) have concave up shape (LaN/YbN = 6.64–11.57) and show negative to slightly positive Eu anomalies (EuN/Eu* = 0.37–1.24). 87Sr/86Sr(i) values of 0.704801–0.705102 and εNd(i) values of 1.01–1.34 correspond to the mantle series on isotope ratio diagrams. Positive εHf(i) values (5.01–14.91) plot between the depleted mantle and the chondritic evolution lines. The petrological features of the rocks from the Arslandede pluton show that fractional crystallization with low rates of assimilation and/or magma mixing were effective during crystallization. All data show that the magma source of the pluton derived from an enriched lithospheric mantle and emplaced into the crust after differentiation in a deep seated magma chamber contaminated by relatively small proportions of crustal rocks.
- MakaleAçık Erişim2024Mineral chemistry, petrography and crystallization conditions of the Middle Eocene Kazıkbeli Pluton (Eastern Pontides, NE Türkiye)
Güloğlu, Zikrullah Samet; Kaygusuz, Abdullah; Aydinçakir, Emre; YÜCELc, Cem
The Eastern Pontides host a diverse suite of plutonic rocks spanning a wide range of ages and compositions. Among these, the Middle Eocene Kazıkbeli pluton, located in the Kürtün district of Gümüşhane, stands out due to its distinctive petrological characteristics. This study aims to unravel the petrological implications of petrographic and mineral chemical data to determine the physicochemical conditions (temperature, pressure, oxygen fugacity) under which the Kazıkbeli magma crystallized and was emplaced. By integrating mineral chemical data, we seek to quantify emplacement pressure, crystallization temperature, and oxygen fugacity. A comprehensive understanding of the genetic relationships and physicochemical properties of the Kazıkbeli pluton rocks, as determined through geological, petrographic and mineral chemistry, is crucial for elucidating the geological evolution of the Eastern Pontides. The Kazıkbeli Pluton exhibits a predominant NE-SW orientation and encompasses an area of roughly 46 km2. Modal mineralogical analysis reveals a compositional spectrum ranging from gabbroic diorite to monzogranite, with granodiorite and tonalite being the most prominent rock types. Textural variations encompass fine-to medium-grained, porphyritic, poikilitic, and occasionally graphic textures. The primary mineral assemblage of the pluton comprises plagioclase, orthoclase, quartz, amphibole, biotite, and Fe-Ti oxides. Accessory minerals include zircon, apatite, sphene, and allanite. Plagioclases are labradorite to oligoclase (An26 to An66) in composition. K-feldspar minerals exhibited an orthoclase composition (Or80 to Or97). All amphiboles belong to the calcic amphibole field and exhibit a magnesio-hornblende (Mg#=0.63-0.73) composition. Biotites crystallized as solidified melt products with compositions between annite and phlogopite endmembers, plotting close to the magnesium-rich (Mg#=0.52-0.58) end of the phlogopite solid solution series. Calculated crystallization temperatures derived from amphibole and biotite data range from 712°C to 824°C. Pressure estimations calculated using amphibole-plagioclase, amphibole and biotite suggest a range of 0.04 to 2.06 kbar. Oxygen fugacity (ƒO2) values calculated using amphibole and biotite fall between -12.5 and -16.1. Amphibole-based water content estimations indicate a range of 3.7% to 5.7% for the pluton. Biotite compositions within the studied Kazıkbeli pluton rocks exhibit characteristics suggestive of a potential mantle origin. Geobarometric calculations based on mineral chemistry data with geological and petrographic features indicate the emplacement of the Kazıkbeli Pluton at relatively shallow depths within the crust (~1 to 8 km).
- MakaleAçık Erişim2024Eocene magmatism related to postcollisional extension in the Eastern Pontides (NE Turkiye): 40Ar-39Ar geochronology, geochemistry, and whole-rock Sr-Nd-Pb-Hf isotopes
Aydinçakir, Emre; Yücel, Cem; Kaygusuz, Abdullah; Bilici, Ozgur; Yilmazer, Sinan; Ruffet, Gilles
The mineral chemistry, whole-rock geochemistry, 40 Ar / 39 Ar dating and Sr-Nd-Pb-Hf isotopes of the Eocene Narman (Erzurum) Volcanic rocks in the southeast of the Eastern Pontides Orogenic Belt (EPOB, NE Turkiye) were investigated. The Narman Volcanites consist of basaltic dyke, basaltic lava, and basaltic volcanic breccia facies. Volcanites contain plagioclase (An34-80), 34-80 ), clinopyroxene (Wo38- 38- 47En41-50Fs5-18), En 41-50 Fs 5-18 ), and olivine (Fo 68-90 ) as phenocrystals with magnetite/titanomagnetite microphenocrysts. New 40 Ar- 39 Ar ages suggest that these volcanic rocks erupted between 44.5 +/- 0.1 and 43.4 +/- 0.1 Ma, within the Middle Eocene (Lutetian). Narman Volcanites have calcalkaline character, with medium-high K content. Volcanites are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE), while they are depleted in terms of high field strength elements (HFSE). Chondrite-normalized rare earth element distributions have concave shape with moderate enrichment (LaN/LuN= N /Lu N = 2.78-7.99), leading to consideration that the magmas forming the volcanics derived from similar sources. Isotopically, the rocks in the Narman Volcanites have low-medium initial 87 Sr/ 86 Sr values (0.70405-0.70485), initial 143 Nd/ 144 Nd values (0.512606-0.512848) and positive Nd i (+0.5 - +5.2). Depleted mantle Nd model ages were T DM1 = 0.29-0.62 Ga and T DM2 =0.43-0.83 Ga. (206Pb/204Pb)i, 206 Pb/ 204 Pb) i , (207Pb/204Pb)i, 207 Pb/ 204 Pb) i , and (208Pb/204Pb)i 208 Pb/ 204 Pb) i values vary in the ranges of 18.246-18.709, 15.578-15.616, and 38.225-38.791, respectively. The initial (176Hf/177Hf)i 176 Hf/ 177 Hf) i ratios for the volcanites are between 0.282770 and 0.283013, while the epsilon Hf values range from +7.6 to +9. All the evidence supports the conclusion that the parental magma for the rocks probably derived from an enriched lithospheric mantle, previously metasomatized by fluids derived from subducted slab during asthenospheric upwelling, due to fragmented asymmetric delamination in a postcollisional extensional tectonic environment.
- MakaleAçık Erişim2023Magmatic evolution of the Calc-alkaline Middle Jurassic igneous rocks in the eastern pontides, NE Turkey: insights from geochemistry, whole-rock Sr-Nd-Pb, in situ zircon Lu-Hf isotopes, and U-Pb geochronology
Aydınçakır, Emre; Yücel, Cem; Kaygusuz, Abdullah; Bilici, Özgür; Yi, Keewook; Jeong, Youn-Joong; Güloğlu, Z. Samet
The Eastern Pontides in NE Turkey hosts a very limited number of plutonic rocks from the Jurassic period. Here we submit new geochemical, Sr-Nd-Pb and zircon Lu-Hf isotope data, and zircon U-Pb ages for plutonic rocks in this region. Zircon U-Pb dating for the Alemdar and Işıkdere plutons yielded an age of 175–170 Ma (Middle Jurassic). The Alemdar and Işıkdere plutons have I-type, medium to high-K calc-alkaline series, and metaluminous to slightly peraluminous characteristics. On PM-normalized diagrams, the plutons are enriched in large-ion lithophile elements (LILEs) with pronounced depletion of high field strength elements (HFSEs, Ta, Nb, Ti). Chondrite-normalized plots for the plutons show variable enrichment in light rare earth elements (LREEs) with depletion of heavy rare earth elements (HREEs). The rocks of the Alemdar Pluton have homogeneous ISr values (0.70585 to 0.70673), low εNd(i) values (−3.9 to −1.6), pozitif εHf(i) values (+3.3 to +9.1), and Hf single-stage model ages (563–712 Ma), whereas those of Işıkdere have high ISr values (0.70666 to 0.70673), low εNd(i) values (−3.9 to −3.8), εHf(i) values (−3.1 to +1.1), and Hf single-stage model ages (791–969 Ma). These values imply that they have different sources. These results suggest that the magma of the Alemdar was formed by the partial melting of a relatively depleted lithospheric mantle wedge interaction of the OIB-like melts, while those of Işıkdere have derived from the partial melting of an enriched mantle metasomatized by slab-derived sediments and then modified by fractional crystallization and crustal contamination in crustal magma chambers. Considering the available data, we conclude that the studied plutons were related to extensional tectonic events during the Middle Jurassic in response to the roll-back of the Paleotethys oceanic slab in the final stage of oceanic closure. These rocks are an example of the formation of deep subduction products following Early Jurassic subduction.
- MakaleAçık Erişim2022Petrogenesis of post-collisional Middle Eocene volcanism in the Eastern Pontides (NE, Turkey): Insights from geochemistry, whole-rock Sr-Nd-Pb isotopes, zircon U-Pb and 40Ar-39Ar geochronology
Aydınçakır, Emre; Yücel, Cem; Ruffet, Gilles; Gücer, Mehmet Ali; Akaryalı, Enver; Kaygusuz, Abdullah
The debate about whether Eocene magmatism is considered to be post-collisional or subduction-related or not still continues. Here we offer new 40Ar-39Ar ad U-Pb zircon geochronology, mineral chemistry, bulk rock and Sr-Nd-Pb isotope geochemistry data obtained from the southern dike (SD) suite, in comparison with the northern dike (ND) suite, from the Eastern Pontides. The geochronological data indicate that the SD suite erupted between 45.89 and 45.10 Ma corresponding to the Lutetian (Middle Eocene). The magmas of the ND suite are characterised by slightly more alkaline affinity compared to the SD suite. The trace and rare earth element (REEs) content of the SD suite is characterised by large ion lithophile element (LILEs; Sr, K2O, Ba, Rb) enrichment and depletion of Nb, Ta, and TiO2 elements to different degree with high Th/Yb ratios, which indicate that the magmas forming the SD and ND suites were derived from lithospheric mantle sources enriched by mostly slab-derived fluids in the spinel stability field. The Sr, Nd and Pb radiogenic isotope ratios of the dikes support the view that the magma for the hydrous group (H-SD) was derived from a relatively more enriched mantle source than the other SD and ND suites. The ND suite and the anhydrous group (A-SD) display similar geochemical features characterised by moderate light earth element (LREE)/heavy rare earth element (HREE) ratios, while the H-SD group has respectively lower LREE/HREE ratios indicating higher melting degree. Detailed considerations of the alkalinity, enrichment and partial melting degree for the source of the studied volcanic rocks indicate that the magmas of the northern dike suite are characterised by slightly more alkaline affinity, whereas the magmas throughout the southern dike suite show increments in the enrichment rate and melting degree. In light of the obtained data and comparative interpretations, the geodynamic evolution and differences in petrogenetic character of the Lutetian magmas from both the northern and southern parts of the Eastern Pontides may be explained by different degrees of melting of a net veined mantle source initially metasomatized by mostly subduction fluids during asthenospheric upwelling due to fragmented asymmetric delamination in a post-collisional extensional tectonic environment.
- MakaleAçık Erişim202240Ar–39 Ar dating, whole-rock and Sr-Nd isotope geochemistry of the Middle Eocene calc-alkaline volcanic rocks in the Bayburt area, Eastern Pontides (NE Turkey): Implications for magma evolution in an extension-related setting
Kaygusuz, Abdullah; Yücel, Cem; Aydınçakır, Emre; Gücer, Mehmet Ali; Ruffet, Gilles
Discussions continue about whether Middle Eocene magmatism in the Eastern Pontides is associated with collision or subduction. This paper presents new whole-rock geochemistry, Sr-Nd isotopic and 40Ar-39Ar age data for Middle Eocene volcanic rocks from the Bayburt area of the Eastern Pontides (NE Turkey) to investigate their sources and evolutionary history. The new 40Ar–39Ar ages reveal that these volcanic rocks erupted between 44.6 ± 0.1 Ma and 43.5 ± 0.1 Ma, within the Lutetian (Middle Eocene). The studied volcanic rocks are composed of basalt, andesite, basaltic andesite and minor dacite lava and pyroclastic rocks. These rocks consist of plagioclase, amphibole, pyroxene, olivine, biotite, sanidine and minor quartz phenocrysts with Fe-Ti oxides. They have microlithic, hyalo-microlithic, porphyritic and rarely glomeroporphyritic textures. The volcanic rocks have low to high-K calc-alkaline affinities. They display enrichment in large-ion lithophile elements and depletion in high-field strength elements with high Th/Yb ratios, which indicate that the magmas forming the volcanic rocks were derived from lithospheric mantle sources enriched by mostly slab-derived fluids in the spinel stability field. 87Sr/86Sr(i) values vary between 0.70485 and 0.70551 and 143Nd/144Nd(i) values vary between 0.51255 and 0.51267. These data correspond to the mantle array on the isotope ratio diagram. The main solidification processes consist of fractional crystallization with minor assimilation. In light of the data obtained in this study together with data from previous studies, petrogenetic character of the Middle Eocene magmas from the southern parts of the Eastern Pontides may be explained by melting of an enriched lithospheric mantle source initially metasomatized by subduction fluids in a post-collisional extensional-related tectonic setting.
- MakaleYalnız künye2021U–Pb zircon ages and petrogenesis of the Late Cretaceous I-type granitoids in arc setting, Eastern Pontides, NE Turkey
Kaygusuz, Abdullah; Arslan, Mehmet; Temizel, İrfan; CemYücel; Aydınçakır, Emre
The Eastern Pontides Orogenic Belt (EPOB) as a well-preserved ancient magmatic arc situated in the eastern part of the Sakarya Zone and has key importance to allow for proper reconstruction of the geodynamic evolution of the region. The region accepted as important part of Alpine–Himalayan Belt comprises of many granitoids of the Late Cretaceous age. This paper presents new mineral chemistry, bulk-rock petrochemistry, U-Pb geochronology and radiogenic and stable isotope geochemistry data from the Arpaköy and Oyman granitoids in the north part of the EPOB to interpretation of the igneous activity and geodynamic evolution of the region in Late Cretaceous era. Emplacement ages of 86.82 ± 0.58 Ma for the Oyman granitoid and 82.0 ± 2.3 Ma for the Arpaköy granitoid according to laser ablation ICP-MS U–Pb zircon dating. The Arpaköy granitoid are gabbro diorite, diorite and granite, whereas the Oyman granitoid are tonalite and granite in composition. They show metaluminous-peraluminous transitional (ASI = 0.79–1.20) low to medium-K calc-alkaline features. The rock samples from granitoids are characterized by enrichment in large ion lithophile elements (LILE) and high field strength elements (HFSE) depletion with concave-upward shapes (LaN/LuN = 1.88 to 6.04). The crystallization temperatures are 648 °C–913 °C and the pressure values are 0.2–3.0 kbar, which indicates emplacement depth of the studied granitoids varying from ~1 to 9 km correspond to shallow crustal depths. They show considerable variations in εNd(i) (−4.02 to 1.50) and 87Sr/86Sr(i) (0.70478–0.70689). The 206Pb/204Pb ratios are between 17.97 and 18.65, and δ18O are varying from +5.4 to +9.3‰. The parental magma of the Arpaköy and Oyman granitoids originated from a melt of the enriched lithospheric mantle and the fractional crystallization and lesser assimilation processes has important role on the evolution of magmas in the shallow crustal levels.
- MakaleYalnız künye2021Crustal Contamination of Tertiary Volcanic Rocks: Evidence from K, U, Th and Radiogenic Heat Production Data in Eastern Pontides (NE Turkey)
Maden, Nafiz; Akaryalı, Enver; Aydınçakır, Emre
Herein, we present new 238U, 232Th, and 40K radionuclide concentrations, density and radiogenic heat production (RHP) data on the Tertiary volcanic rocks outcropping in Borçka, Gumushane and Trabzon regions within the Eastern Pontide Orogenic Belt (EPOB). The mean K values for Trabzon, Borçka and Gümüşhane regions were 2.19 ± 0.87%, 0.90 ± 0.70% and 0.59 ± 0.25%, respectively, the mean U values for Trabzon, Borçka and Gümüşhane regions were 2.12 ± 0.76 ppm and 1.29 ± 0.68 ppm and 0.90 ± 0.32 ppm, and the average Th values were calculated as 6.54 ± 2.32 ppm, 2.49 ± 1.93 ppm and 1.33 ± 0.60 ppm for Trabzon, Borçka and Gümüşhane regions, respectively. The average Th/U values are 3.38 ± 1.48 for the Trabzon region, 2.01 ± 1.22 for the Borçka region, and 1.69 ± 1.09 for the Gümüşhane region. Average U/Th values were calculated as 0.35 ± 0.14, 0.71 ± 0.52 and 0.89 ± 0.72 for the Trabzon, Borçka and Gümüşhane regions, respectively. The RHP values were determined as 1.16 ± 0.35 μW m - 3, 0.58 ± 0.33 μW m - 3 and 0.37 ± 0.10 μW m - 3 for Trabzon, Borçka and Gümüşhane regions, respectively. The Tertiary aged rocks in the EPOB that we have examined within this study scope have been derived from an enriched mantle, previously metasomatized by fluids derived from subducted slab. The parental magma of Eocene basaltic rocks was contaminated with crustal material during the ascension of the magma through the crust or in the shallow-level crustal magma chambers.
- MakaleYalnız künye2021Geochronology, petrogenesis and tectonic importance of Eocene I-type magmatism in the Eastern Pontides, NE Turkey
Vural, Alaaddin; Kaygusuz, Abdullah
Eastern Pontides are hosted to many granitoids with different composition, size and age ranges from Paleozoic to Cenozoic. Of these granitoids, especially those of the Cenozoic age are commonly observed in the southern part of the Eastern Pontides, and rarely in the northern part. This paper focuses on the Eocene aged Avliyana Granitoid, located south of the Eastern Pontides, intruding into Late Cretaceous and Eocene volcanic and sedimentary rocks. The Avliyana Granitoid is mainly diorite and tonalite and composed of plagioclase, quartz, orthoclase, hornblende, biotite, pyroxene, and Fe-Ti oxides. It shows granular, locally poikilitic and micrographic texture. The Avliyana Granitoid has I-type, medium to high-K calc-alkaline, and metaluminous character, and has a narrow SiO2 contents (57–64 wt.%). The rocks are enriched in light rare earth elements (LREEs) and large-ion lithophile element (LILEs), and depleted in high field strength elements (HFSEs). Chondrite-normalized REE distributions are concave shaped (LaN/LuN = 5.87–11.92) and show negative Eu anomaly (Eu / Eu * = 0.55–0.81). Geochemical results show that plagioclase, pyroxene, hornblende, and Fe-Ti oxide fractionation are effective in the development of the rocks. The εNd(i) values of the rocks are between – 1.0 and – 0.1, 87Sr/86Sr(i) values are between 0.70531 and 0.70563, and the model ages (TDM) are between 0.79 and 0.93. U-Pb SHRIMP zircon ages of the Avliyana Granitoid rocks range from 45.60 ± 0.55 to 44.75 ± 0.36 Ma. In calculations made from zircon and apatite, the crystallization temperatures vary between 714 and 867 °C. The data revealed that the parental magma of the Avliyana Granitoid was derived from the enriched lithospheric mantle, and fractional crystallization and lesser assimilation played a role in the evolution of the rocks.
- MakaleYalnız künye2020Eocene I-type magmatism in the Eastern Pontides, NE Turkey: insights into magma genesis and magma-tectonic evolution from whole-rock geochemistry, geochronology and isotope systematics
Kaygusuz, Abdullah; Yücel, Cem; Arslan, Mehmet; Temizel, İrfan; Yi, Keewook; Jeong, Youn-Joong; Siebel, Wolfgang; Sipahi, Ferkan
The Eastern Pontides orogenic belt in NE Turkey hosts numerous I-type plutons of Eocene epoch. Here, we report new U–Pb SHRIMP zircon ages and in situ zircon Lu-Hf isotopes along with bulk-rock geochemical and Sr-Nd-Pb-O isotope data from the Kemerlikdağı, Aydıntepe and Pelitli plutons and mafic microgranular enclaves (MMEs) to constrain their parental melt source(s) and evolutionary processes. U-Pb SHRIMP zircon dating yielded crystallization ages between 45 and 44 Ma for the studied plutons and their MMEs. The plutons range from gabbro to granite and have I-type, medium to high-K calc-alkaline, and metaluminous to slightly peraluminous characteristics. On the primitive mantle-normalized multi-trace-element variations, the plutons and their MMEs are characterized by significant enrichment in LILE/HFSE. Chondrite-normalized REE patterns of the plutons and their MMEs are close to each other and show moderate enrichment with variable negative Eu anomalies. The studied plutons have fairly homogeneous isotope composition (87Sr/86Sr(i) = 0.70502 to 0.70560; εNd(i) = +0.9 to–1.4; δ18O = +5.0 to +8.7‰, εHf(i) =–2.2 to +13.5). The MMEs show medium to high-K calc-alkaline and metaluminous character. Although the isotope signatures of the MMEs (87Sr/86Sr(i) = 0.70508 to 0.70542; εNd(i) = +0.9 to −1.1; δ18O = +5.8 to +8.0, εHf(i) = +4.3 to +10.4) are very similar to those of the host rocks. Fractionation of plagioclase, amphibole, pyroxene and Fe-Ti oxides played an important role in the evolution of the plutons. The isotopic composition of the studied plutons and MMEs are similar to I-type plutons derived from mantle sources. The MMEs show incomplete magma mixing/mingling, representing small bodies of mafic parental magma. The parental magma(s) of the studied plutons were generated from the enriched lithospheric mantle and then modified by fractional crystallisation, and lesser assimilation and mixing/mingling in the crustal magma chambers.
- MakaleYalnız künye2020Temporal, geochemical and geodynamic evolution of the Late Cretaceous subduction zone volcanism in the eastern Sakarya Zone, NE Turkey: Implications for mantle-crust interaction in an arc setting
Aydin, Faruk; Oğuz Saka, Simge; Şen, Cüneyt; Dokuz, Abdurrahman; Aiglsperger, Thomas; Uysal, İbrahim; Kandemir, Raif; Karslı, Orhan; Sarı, Bilal; Başer, Rasim
The Late Cretaceous Artvin volcanic rocks (LCAVs) from the eastern Sakarya zone (ESZ) of NE Turkey are composed of mafic/basaltic (S1-Çatak and S2-Çağlayan) and felsic/acidic (S1-Kızılkaya and S2-Tirebolu) rock types that occurred in two successive stages: (i) first stage (S1: Turonian–Early Santonian) and (ii) second stage (S2: Late Santonian–Campanian). Clinopyroxene thermobarometric results point that the S2-Çağlayan basaltic rocks have crystallised at higher temperatures and under deeper crustal conditions than those of the S1-Çatak basaltic rocks. The LCAVs show a wide compositional spectrum, ranging from tholeiite to calc-alkaline/shoshonite and are typically represented by a geochemical composition resembling subduction-related arc rocks although the 87Sr/86Sr(i) (0.7044–0.7071) and ɛNd(i) values (−0.63 to + 3.47) as well as 206Pb/204Pb(i) (18.07–18.56), 207Pb/204Pb(i) (15.57–15.62) and 208Pb/204Pb(i) (37.12–38.55) ratios show very limited variation. The parent magmas of the S1-Çatak and S2-Çağlayan mafic volcanic rocks were derived from underplated basaltic melts that originated by partial melting of metasomatised spinel lherzolite and spinel-garnet lherzolite, respectively. It is proposed that the compositions of the S1-Kızılkaya (mainly dacitic) and S2-Tirebolu (rhyolitic to trachytic) felsic rocks were particularly controlled by metasomatised mantle–crust interaction and MASH zone + shallow crustal fractionation processes. Our data, together with data from previous studies, suggest that the S1- and S2-mafic and felsic rocks of the LCAVs (~95–75 Ma) are the products of two-stage volcanic event that took place during the northward subduction of the northern Neotethys Ocean (NNO).
- MakaleAçık Erişim2020Emplacement conditions of magma(s) forming Jurassic plutonic rocks in Gümüşhane (Eastern Pontides, Turkey)
Aydinçakir, Emre; Gündüz, Ramazan; Yücel, Cem
In this study, the petrography, mineral chemistry and crystallization conditions were reported for the Alemdar and Işıkdere plutons located in limited areas in the south of the Eastern Pontides. These plutons, which trend mostly in NE-SW directions, were emplaced by cutting the Early-Middle Carboniferous-aged Gümüşhane Granitoid and Early-Middle Jurassic Şenköy formation. Petrographically, the studied plutons are compositionally fine to medium grained quartz-diorite, quartz monzodiorite and tonalite. The rocks in the plutons have granular, poikilitic, monzonitic, graphic and rare porphyritic textures with consist of plagioclase, (An05-92), hornblende (Mg# = 0.52-0.81), biotite (Mg# = 0.32-0.67), orthoclase, quartz and Fe-Ti oxide. According to thermobarometric calculations, plutons have crystallization temperatures, pressures and oxygen fugacity values ranging from 541°C to 938°C, 0.1 to 4.4 kbar, and -23 to-12, respectively. The estimated water content calculated from amphibole is between 4.4 to 7.8%. It can be concluded that the studied plutons were emplaced at mid to shallow crustal depths (~4-15 km).
- MakaleYalnız künye2020Mineralogy, chemistry, and genesis of zeolitization in Eocene tuffs from the Bayburt area (NE Turkey): Constraints on alteration processes of acidic pyroclastic deposits
Cicerali, Derya; Arslan, Mehmet; Yazar, Emel Abdioglu; Yücel, Cem; Temizel, Irfan; Park, Sohyun; Schroeder, Paul A.
Eocene vitric tuffs in the Bayburt area (NE Turkey) possess a dacite-rhyodacite composition and contain abundant altered glass shards and flattened fibrous pumice with lesser amounts of pyrogenic minerals (plagioclase, quartz, biotite, and sanidine). Zeolitization is common and generally develops in the glassy components. The main zeolite mineral found in the tuffs is clinoptilolite, with lesser amounts of analcime and mordenite (?). Smectite is the dominant clay mineral, with lesser amounts of kaolinite also present. Opal-CT, calcite, and dolomite occur as secondary minerals. Scanning electron microscopy studies reveal the dissolution of glass, with the development of popcorn-textured smectites and tabular clinoptilolites developed. The opal-CT spheres found on the clinoptilolite crystals appear to have crystallized simultaneously and are due to excess silica in the environment. Fibrous mordenite (?) also developed on the clinoptilolites. In the clinoptilolites R-r = 0.81-0.82, Si/Al = 4.20-4.70, and K+ is the dominant exchangeable cation (0.65-3.30) seen, together with lesser amount of Ca2+ (0.39-2.25) and Na+ (0.02-2.16). The degree of zeolitization increases with the content of glassy component in the tuffs. The formation of K-clinoptilolite is controlled by the SiO2/Al2O3 (4.9-7.0) and K2O/Na2O (0.8-10.8) ratios in the zeolitized tuffs. delta O-18(V-SMOW) and delta DV-SMOW values of clinoptilolite-rich tuffs range from 22 to 25.6960 and from -96 to -111 parts per thousand, respectively, which suggests that zeolitization occurred at low temperatures (30-55 degrees C) via fluid-rock interactions. Smectite was initially formed from the devitrification of glassy components and is associated with the increase in (Na+ +K+ +Ca2+)/H+ activity and the presence of high pH similar to-9-10) fluids. The zeolites subsequently developed within a saline-alkali shallow marine environment.
- MakaleYalnız künye2019U-Pb geochronology, bulk-rock geochemistry and petrology of Late Cretaceous syenitic plutons in the Gölköy (Ordu) area (NE Turkey): Implications for magma generation in a continental arc extension triggered by slab roll-back
Temizel, İrfan; Arslan, Mehmet; Yücel, Cem; Yazar, Emel Abdioğlu; Kaygusuz, Abdullah; Aslan, Zafer
Late Cretaceous felsic plutons in the Eastern Pontides orogenic belt of Turkey are found in varying ages, sizes and compositions. The Late Cretaceous syenitic bodies, namely Direkli and Yeniköy Tepe plutons in the Ordu area, intruded into the Late Cretaceous volcanics and volcanoclastics, and compositionally consist of syenite and minor quartz-syenite with mainly granular and rarely porphyric, poikilitic and perthitic textures. The studied plutons contain K-feldspar, plagioclase, quartz, clinopyroxene, biotite and minor hornblende, and Fe-Ti oxide, apatite, and zircon. Mineral thermobarometer estimations imply that the syenitic plutons were crystallized in P-T conditions representing mid to shallow crustal levels. Petrochemically, these syenitic plutons show I-type, metaluminous-peraluminous transitional (A/CNK = 0.85–1.04) and shoshonitic features. LA-ICP-MS U-Pb zircon dating on the syenitic plutons yielded weighted mean ages of 78.5–72 Ma. Primitive mantle-normalized trace element patterns of the studied plutons are characterized by negative anomalies of Ba, Sr, Nb, Ta and Ti, and enrichment in Rb, Th, K, Ce and La. The chondrite-normalized rare earth element (REE) plots of the studied plutons show moderately enriched concave-shaped patterns (La N /Lu N = 10.3–10.7 for the Direkli pluton; La N /Lu N = 6.8–11.7 for the Yeniköy Tepe pluton) with negative Eu anomalies. The plutons have 87 Sr/ 86 Sr ratios (0.705368–0.706954), 143 Nd/ 144 Nd ratios (0.512600–0.512672), 206 Pb/ 204 Pb ratios (19.29–19.52) and 207 Pb/ 204 Pb ratios (15.65–15.67). The geochemical data, as well as regional geology, suggest that the Late Cretaceous syenitic plutons have formed in an extensional continental arc setting triggered by slab roll-back. The parental magma of syenitic plutons was derived from melts of lower crustal materials (metabasalt/metaandesite) and lithospheric mantle component.
- MakaleAçık Erişim2018Petrography, mineral chemistry and crystallization conditions of cenozoic plutonic rocks located to the north of Bayburt (Eastern Pontides, Turkey)
Kaygusuz, Abdullah; Yücel, Cem; Arslan, Mehmet; Sipahi, Ferkan; Temizel, Irfan; Çakmak, Gökhan; Güloglu, Z. Samet
The Eastern Pontides comprise many intrusive bodies varying in composition, size and age from Palaeozoic to Cenozoic. Especially Cenozoic aged bodies are commonly observed in the southern part, while they are rarely exposed in the northern part of the Eastern Pontides. In this study, the petrography and mineral chemistry of the Cenozoic aged Çiçekli, Somarova, Sorkunlu, Şaşurluk, Aydintepe, Kemerlikdagi and Pelitli plutons located to the north of Bayburt are determined, and the crystallisation conditions of the studied bodies were estimated by means of thermobarometer calculations. The studied plutons extend mostly in NE-SW directions and are approximately ellipsoid in shape. The contacts between the plutons and surrounding rocks are sharp, and plutons commonly contain mafic microgranular enclaves (MMEs) of different sizes. Petrographic and mineral chemistry studies reveal some disequilibrium textures reflecting the magma mixing process. Based on modal mineralogy, the plutonic rocks are gabbroic diorite, diorite, tonalite, granodiorite and monzogranite in composition. The rocks have fine to medium granular, porphyric, monzonitic, poikilitic, occasionally myrmekitic and micrographic textures. The main minerals are labradorite and albite (An68-02), magnesiohornblende and actinolite (Mg# = 0.6-0.9), diopside and augite (Wo44-46), clinoenstatite (En53-57) and Fe-Ti oxide minerals. Crystallization temperatures calculated from amphibole, biotite, clinopyroxene, magnetite and ilmenite minerals are 405°C to 1161°C, pressure values are 0.1 to 2.7 kbar, and oxygen fugacity (log10 fO2) is -20 to -12. Estimation of water content calculated by using amphiboles is between 2.9 and 6.8%. Based on obtained data, it is suggested that the studied plutons were emplaced at shallow depths (∼ 1-8 km).
- MakaleAçık Erişim2017Evolution of K-rich magmas derived from a net veined lithospheric mantle in an ongoing extensional setting: Geochronology and geochemistry of Eocene and Miocene volcanic rocks from Eastern Pontides (Turkey)
Yücel, Cem; Arslan, Mehmet; Temizel, İrfan; Abdioğlu Yazar, Emel; Ruffet, Gilles
The Eocene and Miocene volcanic rocks between the cities of Trabzon and Giresun in the Eastern Pontides (NE Turkey) erupted as mildly and moderately alkaline magmas ranging from silica-saturated to silica-undersaturated types. 40Ar-39Ar dating and petrochemical data reveal that the studied volcanic rocks are discriminated in two: Lutetian (Middle Eocene) mildly alkaline, (basaltic rocks: 45.31 ± 0.18 to 43.86 ± 0.19 Ma; trachytic rocks: 44.87 ± 0.22 to 41.32 ± 0.12 Ma), and Messinian (Late Miocene) moderately alkaline volcanic rocks (tephrytic rocks: 6.05 ± 0.06 and 5.65 ± 0.06 Ma). The trace and the rare earth element systematic, characterised by moderate light earth element (LREE)/heavy rare earth element (HREE) ratios in the Eocene basaltic and trachytic rocks, high LREE/HREE ratios in the Miocene tephrytic rocks, and different degrees of depletion in Nb, Ta, Ti coupled with high Th/Yb ratios, show that the parental magmas of the volcanic rocks were derived from mantle sources previously enriched by slab-derived fluids and subducted sediments. The Sr, Nd and Pb isotopic composition of the Eocene and Miocene volcanic rocks support the presence of subduction-modified subcontinental lithospheric mantle. During the magma ascent in the crust, parental magmas of both the Eocene and Miocene volcanic rocks were mostly affected by fractional crystallisation rather than assimilation coupled with fractional crystallisation and mixing. The silica-undersaturated character of the Miocene tephrytic rocks could be attributed to assimilation of carbonate rocks within shallow-level magma chambers. The parental magmas of the Eocene volcanic rocks resulted from a relatively high melting degree of a net veined mantle and surrounding peridotites in the spinel stability field due to an increase in temperature, resulting from asthenospheric upwelling related to the extension of lithosphere subsequent to delamination. The parental magmas for the Miocene volcanic rocks resulted from a relatively low melting degree of a net veined mantle domain previously modified by metasomatic melts derived from a garnet peridotite source after decompression due to extensional tectonics, combined with strike-slip movement at a regional scale related to ongoing delamination.
