Insight into magma genesis at convergent plate margins - a case study from the eastern Pontides (NE Turkey)

Kaygusuz A., Siebel W., Ilbeyli N., Arslan M., Satir M., Şen C.

NEUES JAHRBUCH FUR MINERALOGIE-ABHANDLUNGEN, cilt.187, sa.3, ss.265-287, 2010 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 187 Sayı: 3
  • Basım Tarihi: 2010
  • Doi Numarası: 10.1127/0077-7757/2010/0178
  • Dergi Adı: NEUES JAHRBUCH FUR MINERALOGIE-ABHANDLUNGEN
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED)
  • Sayfa Sayıları: ss.265-287
  • Anahtar Kelimeler: Cretaceous-Paleocene, Eastern Pontides, Sr-Nd-Pb isotopes, subduction, arc magmatism, U-Pb SHRIMP, GEOCHEMICAL CHARACTERISTICS, VOLCANIC-ROCKS, I-TYPE, TRACE-ELEMENT, ISOTOPIC COMPOSITIONS, TECTONIC EVOLUTION, GRANITOIDS, AREA, CRUST, SEA
  • Karadeniz Teknik Üniversitesi Adresli: Evet

Özet

Convergent plate margins are the most intense areas of granitoid magmatism on Earth. The Eastern Pontide Magmatic Belt in NE Turkey represents a paleo-arc with numerous quartz diorite to syenite intrusions, ranging in age from 142 to 56 Ma and being composed of K-feldspar, plagioclase, quartz, pyroxene, hornblende, biotite, and Fe-Ti oxides. The granitoids exhibit low-to high-K calc-alkaline, metaluminous to slightly peraluminous I-type features and contain abundant mafic magmatic enclaves (MME). They are characteristically enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE). Chondrite-normalized REE patterns are fractionated (La-N/Lu-N = 1.49-17.4) with pronounced negative Eu anomalies (Eu/Eu* = 0.46-1.77). Initial Sr-87/Sr-86 values are between 0.7056 and 0.7079, and epsilon(Nd(i)) values between -5.3 and 1.6. Fractional crystallization, magma mixing/mingling and crustal contamination played an important role during magma evolution. All these characteristics, combined with the low values of K2O/Na2O, Mg-number, ASI and ratios of Al2O3/(FeOT+MgO+TiO2) and (Na2O+K2O)/(FeOT+MgO+TiO2), suggest an origin by dehydration melting of mafic (amphibolitic) or tonalitic lower crustal source rocks.