GEOCHEMICAL CORRELATION OF POST-COLLISIONAL VOLCANISM FROM THE SAKARYA ZONE (TURKEY)

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7105-98-8 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 11, 191-200 pp, DOI: 10.5593/sgem2017/11/S01.024

ABSTRACT

The Sakarya zone in Anatolia is a continental fragment >1500 km long and 120 km wide. This continent is divided into three zones: western, central and eastern. This volcanism is related to western Anatolia orogenic belt around Sakarya zone which produced Late Eocene-Late Miocene-aged mainly acidic and intermediate volcanic rocks. They are mainly composed of andesite, dacite, and latite lavas with associated pyroclastic rocks. The central Sakarya zone volcanic unit is mainly composed of Eocene-aged andesite and dacite lavas, agglomerates and lithic tuffs. In the eastern Sakarya zone, the volcanic complex consists of a plug dome and lava flows with compositions ranging from basic andesite to rhyolite. Two distinct episodes of volcanic activity in this zone occurred in western and central Sakarya zone around Early and Late Miocene. The Early Miocene volcanic sequence ranges in composition from K-rich basaltic trachyandesite to rhyolite, whereas the Late Miocene volcanic rocks are alkali basalt in composition.The Eocene-Miocene volcanic rocks of the Sakarya zone are mainly high-K calc-alkaline. They display enrichment in LILE and LREE relative to HFSE. These characteristics indicate an enriched mantle source region(s) carrying a subduction component inherited from pre-collision subduction events. The removal of subduction results in the progressive change of the chemistry of the volcanism from calc-alkaline to midly alkaline to alkaline through time was accompanied by crustal to lithosperic scale extension and decreasing amounts of subduction signature and crustal contamination.

Keywords: Anatolia, Sakarya zone, Late Cenozoic, volcanism, geochemistry