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- MakaleAçık Erişim2018Mineral chemistry, whole-rock geochemistry and petrology of Eocene I-type shoshonitic plutons in the Gölköy area (Ordu, NE Turkey)
Temizel, Irfan; Abdioǧlu Yazar, Emel; Arslan, Mehmet; Kaygusuz, Abdullah; Aslan, Zafer
The Eocene intermediate to felsic plutons are widespread in varying sizes and compositions throughout the Eastern Pontides Orogenic Belt in NE Turkey. Of these, two monzonitic bodies (namely the Eriko Tepe and Göl Tepe Plutons) in the Gölköy (Ordu) area, extend nearly in the orientation of NWSE and E-W and were emplaced into the Upper Cretaceous and/or Eocene volcanic and sedimentary rocks. Petrographically, the studied monzonitic plutons are compositionally fine to medium grained monzonite, monzodiorite and subordinate quartz-monzonite. They consist of plagioclase (An35-67), K-feldspar (Or61-96), quartz, clinopyroxene (Wo28-49En35-51Fs10-25), biotite (Mg#: 0.53-0.73) ± hornblende (Mg#: 0.65-0.82), Fe-Ti oxide with monzonitic, poikilitic, perthitic, rare antirapakivi and graphic textures. Mineral thermobarometer estimations imply that the plutons were crystallized in P-T conditions of mid to shallow crustal levels. Petrochemically, these monzonitic plutons show post-collisional, I-type, metaluminous (A/CNK=0.76-0.93) and shoshonitic features. The wholerock major oxide and trace element variations suggest that fractionational crystallization played a significant role in the evolution of these monzonitic plutons. The primitive mantle-normalized trace element patterns of the studied plutons are similar to each other with enrichment in large ion lithophile elements, Th, Ce and negative Nb and Ti anomalies. Moreover, the chondrite-normalized rare earth element plots of the plutons show moderately enriched concave-shaped patterns (LaN/LuN=9.3-12.6) with negative Eu anomalies (EuN/Eu∗=0.69-0.84), all of which imply plagioclase and clinopyroxene ± hornblende fractionations during their evolution. The geochemical data suggest that the monzonitic plutons have evolved from parental magmas derived from the melts of enriched lithospheric mantle, in a post-collisional setting.
- MakaleYalnız künye2014LA-ICP MS zircon dating, whole-rock and Sr-Nd-Pb-O isotope geochemistry of the Camiboǧazi pluton, Eastern Pontides, NE Turkey: Implications for lithospheric mantle and lower crustal sources in arc-related I-type magmatism
Kaygusuz, Abdullah; Arslan, Mehmet; Siebel, Wolfgang; Sipahi, Ferkan; Ilbeyli, Nurdane; Temizel, Irfan
Late Cretaceous I-type plutons are widespread in the Eastern Pontides, NE Turkey. The studied Camiboǧazi pluton is a composite pluton consisting of diorite, tonalite, monzodiorite, monzonite, quartz monzonite, granite, and mafic microgranular enclaves (MMEs). Laser ablation ICP-MS U-Pb dating of zircon yielded crystallization ages of 76.21±0.79Ma, 75.65±0.50Ma, 75.04±0.83Ma, and 74.73±0.86Ma for diorite, monzodiorite, monzonite, and granite, respectively. The rocks of the pluton have I-type, high-K to shoshonitic and metaluminous character, displaying whole-rock geochemical features of arc-related granites. They are enriched in large-ion lithophile and light rare-earth elements, and depleted in high-field-strength elements. Major element variations can be attributed to fractionation of plagioclase, clinopyroxene, hornblende, and Fe-Ti oxides. The rocks show considerable variation in 87Sr/86Sr(i) (0.70498 to 0.70622), εNd(i) (-2.79 to -0.36), δ18O values (+6.3 to +11.4) and Nd model ages (TDM) (0.81Ga to 1.26Ga). Besides, they have (206Pb/204Pb)=18.44-19.09, (207Pb/204Pb)=15.64-15.69, and (208Pb/204Pb)=38.37-38.89. Although isotope signatures of the mafic microgranular enclaves (MMEs) (87Sr/86Sr(i)=0.70551 to 0.70622; εNd(i)=-2.9 to -1.23; δ18O=+8.3 to +9.7) are largely similar to the host rocks, MMEs are characterized by relatively high Mg-numbers (32-36), low contents of SiO2 (52-56wt.%) and low ASI (0.7-0.9). Estimated crystallization temperatures for the rocks of the pluton range from 735±58°C to 844±24°C and a shallow intrusion depth (<10km) is estimated from Al-in-hornblende thermobarometry. Whole-rock geochemical and isotopic data suggest magma generation by dehydration melting of an amphibolite-type lower crustal component with additional input of a subcontinental lithospheric mantle component. Furthermore, Sr-Nd isotope mixing model reveals ~30% to 40% lower crustal magma contribution to the mantle component.
- MakaleAçık Erişim2009U-Pb SHRIMP zircon ages, geochemical and Sr-Nd isotopic compositions of the late cretaceous I-type Sariosman pluton, Eastern Pontides, NE Turkey
Kaygusuz, Abdullah; Chen, Bin; Aslan, Zafer; Siebel, Wolfgang; Şen, Cüneyt
The petrogenesis and U-Pb SHRIMP zircon ages of the Late Cretaceous Sariosman pluton in the Eastern Pontides is investigated by means of whole-rock Sr-Nd isotope data with field, petrographic and whole-rock geochemical studies. The bulk of the I-type Sariosman pluton consists of biotite-hornblende monzogranite, with minor quantities of porphyritic hornblende-biotite monzogranite. The biotite-hornblende monzogranite contains a number of mafic microgranular enclaves (MMEs) of quartz monzodiorite composition. U-Pb zircon sensitive high-resolution ion microprobe dating (SHRIMP) dates the magma emplacement age of the biotite-hornblende monzogranite at 82.7±1.5 Ma. The rocks of the pluton show high-K calc-alkaline, metaluminous to slightly peraluminous characteristics, and are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE), thus displaying features of arc-related granitoids. Chondrite-normalised rare earth-element (REE) patterns have concave upward shapes (Lacn/Lucn= 10.1-17.4) with pronounced negative Eu anomalies (Eu/Eu*= 0.61-0.80). Initial εNd values vary between -3.0 and -4.1 and initial 87Sr/86Sr values between 0.7062 and 0.707. The MMEs are characterised by higher Mg-numbers (27-29) and lower values of both SiO2 (56-58 wt%) and aluminium saturation index (0.9-1.0), compared to the monzogranites. Fractionation of plagioclase, hornblende and Fe-Ti oxides played an important role in the evolution of the Sariosman pluton. The crystallisation temperatures of the melts ranged from 700 to 800 °C and a relatively shallow intrusion depth (~2 to 7 km) is estimated from the Al-in-hornblende geobarometry. The geochemical and isotopic compositions of the Sariosman pluton suggest an origin through dehydration melting of mafic lower crustal source rocks.