Geochemical constraints on the genesis of the Sancakaya intrusive rocks, Turkey: Late Paleozoic crustal melting in the central Sakarya Zone

摘要

The Sakarya Zone is intruded by several Late Paleozoic granitoids, of which the Sancakaya intrusive rocks in the central Sakarya (Eski§ehir) region, is the least-studied. The Sancakaya intrusive rocks consist mainly of quartz diorite-granodiorite, granodiorite and granite. They are, geochemically, divided into two groups: diorites and granites. The former is medium-K and calc-alkaline (mainly I-type), whereas the latter is high-K to shoshonite and calcic (I-type). Typical minerals for both rock types are plagiodase, K-feldspar, quartz, biotite, hornblende and Fe-Ti oxides. Chondrite-normalized REE patterns for the Sancakaya intrusive rocks are moderately fractionated and have small negative Eu anomalies. They are enriched in LILE and LREE relative to HFSE showing characteristics of arc-related granitoids. Geochemical characteristics of the Sancakaya intrusive rocks indicate a hybrid origin through partial melting of lower crustal source rocks.