Evidence for dynamic relationship between faulting and Neogene-Quaternary volcanism in post-collisional Central Anatolia (Turkey): Implications for shallow slab subduction and rollback

To investigate the tectonic and structural mechanisms that produced the spatial-temporal patterns of volcanism within the complex geodynamic setting of Central Anatolia, we obtained 25 new 40Ar/39Ar ages across the Miocene-Quaternary Central Anatolia Volcanic Province to constrain the ages of several individual volcanic centers. Based on the onset and duration of volcanism, we identify several Miocene-Pliocene time-progressive volcanic lineaments that are spatially and temporally associated with the Central Anatolia and Tuzgolu fault zones and the basins they developed. These new ages, coupled with existing kinematic data and geologic relationships, suggest that volcanism flared up at ca. 12 Ma after a long-lived magmatic lull in the area. Volcanism primarily migrated adjacent and parallel to transtensional and extensional fault zones and basin margins in a post-collisional extensional environment during overall plateau uplift. Regionally, the onset and duration of volcanism overwhelmingly migrated toward the southwest between ca. 12-2.5 Ma. Based on inferences from the geologic record and modern seismic observations, we suggest that the occurrence and southwest migration of magmatism in Central Anatolia was the result of southwest rollback of the Cyprean slab, which is partially torn laterally and currently dipping vertically beneath the Central Taurus Mountains. According to this model, the beginning of post-collisional extension in the early Miocene predated slab rollback and was related to complex regional tectonics of the Aegean, Anatolia, and Caucasus regions. We suggest that slab rollback induced dynamic subsidence, volcanism, and uplift above the migrating slab hinge from ca. 12-2.5 Ma. In contrast, Quaternary volcanism (ca. 2.5-0 Ma), which shows no evidence for temporal patterns, occurs in a broad NE-SW trend similar in distribution to Miocene-Pliocene volcanism and may be the product of adiabatic melting and tectonic escape following slab rollback, perhaps aided by upwelling mantle through and around the vertically-dipping and torn Cyprean slab