Relative involvement of mantle and crustal components in the Agacoren granitoid (central Anatolia, Turkey): Estimates from trace element and Sr-isotope data


Gulec N. , Kadioglu Y.

CHEMIE DER ERDE-GEOCHEMISTRY, cilt.58, ss.23-37, 1998 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 58
  • Basım Tarihi: 1998
  • Dergi Adı: CHEMIE DER ERDE-GEOCHEMISTRY
  • Sayfa Sayıları: ss.23-37

Özet

Trace element contents, together with Sr-isotope ratios on a limited number of samples, are reported for the central part of the Agacoren granitoid in central Anatolia (Turkey), Trace element contents are depicted in terms of Ocean Ridge Granitoid (ORG)-normalized elemental patterns. The patterns display similarities to Volcanic Arc Granitoids (VAG) and/or Collision Granitoids (COLG), and are characterized by enrichment in Large Ion Lithophile (LIL) elements relative to High Field Strength (HFS) elements, negative Ba and positive Rb, Th and Ce anomalies, and high Th/Nb ratios. A comparison with the patterns typical of upper continental crust, lower continental crust and volcanic are calc-alkaline basalt implies that the Agacoren granitoid inherited its pattern essentially from the upper crust, although inheritance-in part-from a subduction modified upper mantle is also possible. Plot of Rb/Sr ratios against the initial Sr-87/Sr-86 ratios at the time of granitoid intrusion (110 Ma) suggests the derivation of granitoid from a mixture of about 70% (upper) crustal + 30% mantle components, the mixture later undergoing a maximum of about 21% fractional crystallization. The relative proportion of mantle and crustal components, as constrained from the isotope data, exceeds the limits-for complete hybridization-imposed by mechanical and thermal arguments, but falls into the range for commingling (incomplete mixing) of mafic and felsic magmas, the validity of which is also supported by the presence of mafic microgranular enclaves in the granitoid. The modeling of trace element data based on the estimates from isotope data yield elemental patterns generally conformable to those displayed by granitic samples.