Structure of the Kizildag ophiolite, a slow-spread Cretaceous ridge segment north of the Arabian promontory

Abstract

The Cretaceous Kizildag ophiolite in southern Turkey is part of the Neotethyan ophiolite belt around the Arabian promontory and consists of two structurally distinct massifs that are separated by a northwest-striking high-angle oblique fault. This fault is interpreted as an accommodation zone that permitted differential movements between the adjacent crustal blocks during the evolution of the ophiolite. The main massif to the west includes an antiformal peridotite core adjoined on the southeast by the normal-fault-bounded plutonic sequence and sheeted dike complex, which collectively form a structural graben reminiscent of slow-spreading ridge axes. The inferred spreading axis and axis-parallel fault contacts are intersected and offset at right angles by tear faults that are geometrically and kinematically analogous to transfer faults in modern oceanic lithosphere at slow-spreading ridge environments. The secondary massif to the east consists mainly of serpentinized peridotites directly overlain along tectonic and/or intrusive contacts by lava flows, rotated dike blocks, and plutonic rocks, and can be interpreted as a segment of oceanic lithosphere evolved at and near the accommodation zone. The general structure of the ophiolite suggests its evolution via magmatic accretion and subsequent tectonic extension along a low-angle shear zone at a slow-spreading ridge environment.