Mineralogy, whole-rock and Sr-Nd isotope geochemistry of mafic microgranular enclaves in Cretaceous Dagbasi granitoids, Eastern Pontides, NE Turkey: Evidence of magma mixing, mingling and chemical equilibration


Kaygusuz A., Aydincakir E.

CHEMIE DER ERDE-GEOCHEMISTRY, cilt.69, ss.247-277, 2009 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 69 Konu: 3
  • Basım Tarihi: 2009
  • Doi Numarası: 10.1016/j.chemer.2008.08.002
  • Dergi Adı: CHEMIE DER ERDE-GEOCHEMISTRY
  • Sayfa Sayıları: ss.247-277

Özet

Rocks of the Late Cretaceous Dagbasi Pluton (88-83Ma), located in the eastern Pontides, include mafic microgranular enclaves (MMEs) ranging from a few centimetres to metres in size, and from ellipsoidal to ovoid in shape. The MMEs are composed of gabbroic diorite, diorite and tonalite, whereas the felsic host rocks comprise mainly tonalite, granodiorite and monzogranite based on both mineralogical and chemical compositions. MMEs are characterized by a fine-grained, equigranular and hypidiomorphic texture. The common texture of felsic host rocks is equigranular and also reveals some special types of microscopic textures, e.g., oscillatory-zoned plagioclase, poikilitic K-feldspar, small lath-shaped plagioclase in large plagioclase, blade-shaped biotite, acicular apatite, spike zones in plagioclase and spongy-cellular plagioclase textures and rounded plagioclase megacrysts in MMEs. Compositions of plagioclases (An(33)-An(60)), hornblendes (Mg# = 0.77-1.0) and biotites (Mg# = 0.61-0.63) of MMEs are slightly distinct or similar to those of host rocks (An(12-57); hbl Mg# = 0.63-1.0; Bi Mg# = 0.50-0.69), which suggest partial to complete equilibration during mafic-felsic magma interactions.