2nd International Symposium on the Geology of the Black Sea Region (ISGB-2), Ankara, Turkey, 1 - 04 October 2009, pp.106-107
Late Cretaceous volcanism across the Western Pontides followed two stages of activity: Early and Late Stages. During the Early Stage between Middle Turonian and end of Coniacian, lavas with a calc-alkaline character and a distinct subduction signature erupted (i.e. Dereköy fm. in the East and Bozhane fm. in the West). The aforementioned lavas and associated volcaniclastics are intercalated with deep marine sediments. The volcanic activity ceased throughout the W Pontides between Late Santonian and Early Campanian, during the deposition of a red pelagic carbonates (i.e. Unaz fm.). By Early Campanian (i.e. the Late Stage), volcanic activity was resumed all over the region during the deposition of Cambu formation in the East and Garipçe formation in the West. Volcanic activity became more intensified during the Late Stage, producing a much greater volume of volcanic material compared to that of the Early Stage. At the beginning, calcalkaline lavas dominated the volcanic sequence however, around the middle of the Late Stage, alkaline and mildly-alkaline (mostly aphyric & occasionally pillowed) lavas began erupting, intercalated with calcalkaline lavas. These two contrasting magma series interacted intensively with each other via magma mixing during their magma chamber evolutions. Alkaline lavas became gradually dominant towards the end of the Late Stage while lavas chemistry, in general, was becoming more basic. Our data support a model for the genesis of the Late Cretaceous lavas, in which magma generation was associated with an extensional arc setting whose final stage was influenced by an oceanic spreading ridge-trench collision.
Keywords: Western Pontides, Late Cretaceous, subduction component, magma mixing, ridge subduction.