Geology, geochemistry, and the evolution of an oceanic crustal rift at Sithonia, NE Greece

Abstract

At Sithonia an approximately 3km thick pseudostratified volcanic arc consisting of abyssal volcanics intruded by granophyres and alternating with turbidites and platform limestones is exposed. During the Late Jurassic, the volcanic arc was subjected to short-termed rifting that resulted in the formation of an oceanic crustal sequence comprising a sheeted dyke complex, submarine volcanics and a coeval Upper Jurassic shallow-water sedimentary cover. Field relations indicate that this sequence was created within a wall-to-wall. NE-trending rift that is at most 30k wide and 10km long. Rifting commenced without passing through phases of extensional faulting, subsidence and sedimentation. The sheeted dykes immediately invaded the previously deformed arc volcanics. Rift-related magmatism is meager and is restricted to microdioritic dykes of island-arc affinity. After a spreading period of at most 1.5 Ma, the rift closed by NE-directed overthrusting of first its axial sequence along a former transform onto the adjacent arc volcanics prior to the SW transport of the Serbomacedonian massif. -from Author