TECTONIC SIGNIFICANCE OF THE GEOCHEMISTRY AND PETROLOGY OF THE TEKIROVA (ANTALYA) OPHIOLITE, SOUTHERN TURKEY

10th International Multidisciplinary Scientific GeoConference - SGEM2010, www.sgem.org, SGEM2010 Conference Proceedings/ ISBN 10: 954-91818-1-2, June 20-26, 2010, Vol. 1, 157-164 pp

ABSTRACT

The Tekirova (Antalya) ophiolite is located at the southwestern part of the Antalya
complex along the Tauride belt in southern Turkey. The Tekirova (Antalya) ophiolite
pseudostratigraphy such as, in an ascending order: harzburgitic tectonites, ultramaficmafic
cumulates, isotropic gabbros and sheeted dikes. Comagmatic volcanics rocks in
the Tekirova ophiolite are not preserved and metamorphic sole rocks under the
harzburgitic tectonites. Numerous isolated dikes, ranging in thickness from 5 cm to 10
m, intruded the crustal rocks at different structural levels. The ultramafic-mafic
cumulate rocks are composed of wehrlite, lherzolite, olivine clinopyroxenite, olivine
gabbronorite, olivine gabbro, gabbronorite and gabbro. These rocks are characterized by
igneous layering-lamination, cross-bedding, graded bedding, isoclinal folding and
slump structures. The crystallization order within the cumulates is olivine (Fo88-
76)±chromian spinel, clinopyroxene (Mg#92-76), orthopyroxene (Mg#86-70), plagioclase
(An97-84). The presence of high Ca-plagioclase, highly magnesian olivine,
clinopyroxene, orthopyroxene and their coexistency in the cumulate gabbroic rocks are
indicative of subduction-related tectonic environment and suggest that the cumulates of
the Tekirova ophiolite were derived from an island arc tholeiitic (IAT) magma. The
isotropic gabbros are represented by gabbro, diorite and quartz diorite rocks with
granular to ophitic–subophitic textures. The isolated dikes are characterized by dolerite,
diabase and microdiorite with ophitic, intersertal and microgranular textures. The major
and trace element geochemistry of the isotropic gabbros and isolated dikes show three
different magma types. These are (i) IAT series comprising the Group I isotropic
gabbros and sheeted dikes; (ii) Low-Ti boninitic series characterized by the Group II
isotropic gabbros and sheeted dikes; (iii) OIB-type including the Group III isotropic
gabbros. All the geochemical evidence suggests that the oceanic crustal rocks of the
Tekirova (Antalya) ophiolite were generated from progressive source depletion from
island arc tholeiites (IAT) to boninites and formed in a fore-arc tectonic setting during
the closure of the southern branch of the Neotethys in Late Cretaceous.

Keywords: Suprasubduction, island arc tholeiite, boninite, alkaline, fore-arc, Turkey