The Geology and Evolution of the Tokat Massif, South-Central Pontides, Turkey

Abstract

The Tokat Massif is a major metamorphic complex of the south-central Pontides, the origin and development of which have long remained unknown. Recent detailed field-based mapping has revealed the major geological features of this complex. The Tokat Massif appears to be a tectonic mosaic composed of three major components: (1) the Yesilirmak Group; (2) the Turhal Metaophiolite; and (3) the Amasya Group. The Yesilirmak Group, which consists of a coherent lithoiogical sequence involving Paleozoic basement and overlying Triassic units, represents a short-lived basin assemblage. The Turhal Metaophiolite consists of an ophiolitic melange association and slices of a stratigraphically ordered ophiolite. The Amasya Group, the highest-standing tectonic unit, is represented by a lower Paleozoic clastic succession. The different major tectonostratigraphic assemblages of the Tokat Massif record a continent-continent collision between the Laurasian Amasya Group and the Gondwanan Yesilirmak Group. The Turhal Metaophiolite, sandwiched between the two continental fragments, represents remnants of an oceanic realm that was consumed between the two continents. The three major tectonic components were assembled and underwent regional metamorphism during the Late Triassic-Liassic transition, and were later covered during the Liassic by basal detrital units.