Research Information System
Earth, Planet and Space, vol.56, pp.429-446, 2004 (SCI-Expanded)
The Pontides are an east-west trending orogenic belt which is subdivided into west, middle and eastern sectors
according to their different tectonostratigraphy. The Eastern Pontides are represented by west-east-trending tectonic
zones resulted from a common Mesozoic-Tertiary history, comprises dominantly of magmatic rocks. The magmatic
belt in the Eastern Pontides includes a large batholith, termed the Composite Kac¸kar Batholith (CKB) in which there
are various granitic facies. The emplacement of CKB occurred in pulses between the Early Cretaceous and Eocene
period during the development of the eastern Pontide magmatic arc and following collisional events. The members
of the CKB are Dereli-S¸ ebinkarahisar (Giresun) in the west, southern Araklı (Trabzon) in the middle and Kac¸kar
Mountain and its surrounding area (Rize) in the east. The plutons ranging from syenite through monzonite to
granite are typically medium-high K calc-alkaline rarely tholeiitic and metaluminous I-type. The studied members
of the CKB intrudes into the Late Cretaceous arc volcanics and are determined to be Late Cretaceous-Eocene
(75
.7 ± 1.55; 41.2 ± 0.89) in K-Ar age. The tectono-magmatic setting of the granitoids has been interpreted as an
arc-related granitic suite, a post-collisional granitic suite and a post-orogenic granitic suite. Some plutons including
mafic magmatic enclaves (MME) and K-feldspar megacrystals suggest magma. mixing/mingling. HFS and LIL
element geochemistry of the granitic intrusions also suggest that fractional crystallization, magma mixing/mingling
and crustal contamination played an important role in the evolution of the CKB. All the data mentioned above
show that the granitoids in the three different regions may have been derived from an arc, developed in response to
the northward subduction of the northern branch of neo-Tethyan oceanic crust beneath the Eurasian plate in Late
Cretaceous and a collision between the Pontide arc and the Anatolide-Tauride platform in Paleocene.
Key words:
Granite, Turkey, arc magmatism, collision; Eastern Pontides.