Geochemistry and Significance of Mafic Dyke Swarms in the Pozantı-Karsantı Ophiolite (Southern Turkey)


Abstract: The Pozantı-Karsantı ophiolite, which is one of a number of the Late Cretaceous oceanic lithospheric remnants in southern Turkey, is situated in the eastern Tauride belt and consists of three distinct thrust sheets: an ophiolitic melange, a metamorphic sole, and an ophiolitic stratigraphic sequence. These units (except the ophiolitic melange) are intruded by isolated microgabbro-diabase dykes at all structural levels. The dykes from the lower crustal rocks (cumulates) are subalkaline in character and chemically similar to island arc tholeiitic basalts and basaltic andesites. They are enriched in some LIL elements (Rb, Ba, K and Sr) and depleted in HFS elements (Nb, Ti, Y) relative to N-MORB. The presence of positive Th and LIL anomalies and a negative Nb anomaly, relative to the other incompatible elements, are thought to represent a subduction zone component. Tectonomagmatic discrimination diagrams based on the immobile trace elements suggest a suprasubduction zone environment for the origin of the mafic dyke swarms. All the evidence indicates that the mafic dykes from the lower crustal rocks (cumulates) in the Pozantı-Karsantı ophiolite formed in the same geodynamic environment (suprasubduction zone) as their host rocks did in the north of Tauride-Anatolide block during Late Cretaceous in the Neo-Tethyan ocean.

Keywords: Isolated dyke, Geochemistry, Supra-subduction zone, Pozantı-Karsantı ophiolite, Southern Turkey

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