S-I-A-type Intrusive Associations: Geodynamic Significance of Synchronism Between Metamorphism and Magmatism in Central Anatolia, Turkey

Abstract

Abstract The Central Anatolian crystalline region, comprising metasediments, ophiolitic slabs and numerous intrusives, has been called the Kırşehir Massif, the Kırşehir Block or Central Anatolian Crystalline Complex. Intrusive associations in Central Anatolia are summarized as: (1) a syncollisional, S (or C ST )-type, peraluminous and two-mica leuco-granitic association; (2) a post-collisional, I (or H LO )-type, metaluminous, high-K calcalkaline, typically K-feldspar megacrystic monzonitic association; and (3) an A-type, post-collisional and within-plate alkaline association comprising a high-K and silica-oversaturated alkaline, K-feldspar megacrystic monzonitic and synoptic subgroup, and a silica-undersaturated alkaline feldspathoid-sodalite syenite porphyry subgroup. Radiometric data suggest that metamorphism and magmatism in Central Anatolia were synchronous during the Late Cretaceous. This implies that metamorphism may have been generated by inverted metamorphism induced by the Anatolide-Pontide collision and was linked to a decreasing metamorphic grade from the north (i.e. from the main suture zone) towards the south (i.e. Taurides). Collision-related intrusive rocks within this crystalline body reflect differences in geological setting, mineralogical-chemical composition and associated ore deposition. Published data considering the distribution and timing of metamorphism and magmatism in the Central Anatolia suggest that both are related to the Anatolide-Pontide collision along the İzmir-Ankara-Erzincan Suture Zone in the Late Cretaceous. Various magmatic episodes affected along the passive margin of the Anatolides, including a syncollisional peraluminous episode, a post-collisional calc-alkaline hybrid and a post-collisional within-plate alkaline episode.