Journals / Turkish Journal of Earth Sciences / 2004 / Cilt: 13 - Sayı: 3
Field, Petrographic and Geochemical Characteristics of the Hamit Alkaline Intrusion in the Central Anatolian Crystalline Complex, Turkey
- Pages
- 269–286
- DOI
- —
Abstract
The Hamit pluton is one of the alkaline intrusions in the Central Anatolian Crystalline Complex (CACC). The pluton consists of nepheline syenite, pseudoleucite syenite, alkali-feldspar syenite and quartz syenite. The nepheline syenite and pseudoleucite syenite are cut by foid-bearing microsyenitic dykes, whereas the alkali-feldspar syenite and quartz syenite are cut by aplitic and silicic dykes. The predominantly peralkaline Hamit intrusive rocks possess field, petrographic and geochemical characteristics comparable to A-type granites. All intrusive rocks of this pluton show enrichment in LILE and LREE relative to HFSE. The Th/Yb versus Ta/Yb plot suggests that the intrusive rocks formed from an enriched mantle source region carrying a subduction component inherited from pre-collision subduction events. Either thermal perturbation of the metasomatised lithosphere by delamination of the thermal boundary layer (TBL) or removal of a subducted plate (slab breakoff) are the likely mechanisms for initiation of the post-collisional magmatism of this complex.
Özet
Hamit plütonu, Orta Anadolu Kristalen Kompleksi (OAKK) içerisinde yeralan alkalen intrüzyonlardan biridir. Plüton, nefelin siyenit, psödolösit siyenit, alkali feldspat siyenit ve kuvars siyenitden meydana gelir. Nefelin siyenit ve psödolösit siyenit, foidli mikrosyenitik dayklar taraf›ndan kesilirken, alkali feldspat siyenit ve kuvars siyenit ise aplitik ve silisli dayklar taraf›ndan kesilir. Peralkalen Hamit intrüzif kayaçlar› arazi, petrografik ve jeokimyasal özellikleri ile A-tipi granitlere benzerlik gösterirler. Tüm intrüzif kayaçlar HFSE nazaran, LILE ve LREE ile zenginleflmifltir. Th/Yb–Ta/Yb diyagram›, intrüzif kayaçlar için kaynak bölgesinin, çarp›flma öncesi dalma-batma olay› ile zenginleflmifl manto oldu¤unu göstermektedir. Kompleks de çarp›flma sonras› magmatizman›n bafllang›c› için uygun mekanizmalar, ya metasomatize olmufl litosferin termal s›n›r tabakas›n›n (TST) delaminasyonu ya da dalmakta olan levhan›n (k›r›l›p?) yok edilmesidir (slab breakoff).