INTERNATIONAL GEOLOGY REVIEW, no.39, pp.365-382, 1997 (Refereed Journals of Other Institutions)
T h e Tokat Massif is a major metamorphi c complex of the south-centra l Pontides, th e origin and development of which have long remained unknown . Recent detailed field-based mapping has revealed th e major geological features of this complex. The Tokat Massif appears to be a tectoni c mosai c composed of thre e major components: (1) th e Yesilirmak Group ; (2) the Turha l Metaophiolite ; and (3) th e Amasya Group. Th e Yesilirmak Group, which consists of a coherent lithoiogical sequenc e involving Paleozoic basement and overlying Triassic units, represents a short-lived basin assemblage. Th e Turhal Metaophiolit e consists of an ophiolitic mélange association and slices of a stratigraphically ordered ophiolite. The Amasya Group, th e higheststanding tectoni c unit, is represented by a lower Paleozoic clastic succession. T h e different major tectonostratigraphi c assemblages of the Tokat Massif record a continentcontinen t collision between the Laurasian Amasya Group an d the Gondwana n Yesilirmak Group. T h e Turhal Metaophiolite , sandwiched between the two continenta l fragments, represents remnants of an oceani c realm that was consume d between th e two continents. Th e thre e major tectoni c components were assembled and underwen t regional metamorphism durin g the Late Triassic-Liassic transition, and were later covered durin g the Liassic by basal detrital units.