T110 Modern to Precambrian Subduction Systems: Convergent Margin Behavior and Evolution Over Geologic Time II

Monday, 23 October 2006
1:30 PM - 5:30 PM

CHANGE FROM CONVERGENT TO COLLISIONAL TRANSFORM BOUNDARY CONDITIONS BETWEEN THE AFRICAN AND ANATOLIAN PLATES, BASED ON THE GEOLOGY OF CYPRUS

Paper number: T110-16
Program: Technical Sessions
Time: 5:15 PM – 5:30 PM

Authors

Abstract

Located on the Anatolian plate adjacent to its boundary with the African plate, the island of Cyprus occupies a valuable position for interpreting the Late Cretaceous & Cenozoic history of plate boundary conditions in the Eastern Mediterranean. The geologic record of Cyprus indicates that Late Cretaceous was the last period of active subduction (convergence); tectonic mélanges of Late Cretaceous deep-water sediments & oceanic crust mark a destructive, compressional plate margin, probably related to northward subduction. However, there are no other indications of any subsequent subduction along this segment of the plate margin; rather, the geologic record is consistent with development in Late Cretaceous of major left-lateral transform faults along & near the plate boundary that have remained persistent throughout the Cenozoic. Obduction & CCW rotation of oceanic crust (Troodos) is interpreted as being the result of shear coupling across these transform faults. The Ovgos fault zone in northern Cyprus is one of these transform structures that was active in the Paleogene & Miocene; as a boundary between areas of transtension & transpression, it juxtaposed differing sedimentary units of deep-marine & shallow-platform origin. Escape tectonics of the Anatolian plate (including Cyprus) was initiated by changes in relative plate motions at ~5Ma.

The present-day tectonic setting is typified by the recently discovered Larnaca fault zone (LFZ), which is an active, >40 km-long, NNE-trending, left-lateral strike-slip structure; late Pleistocene and Holocene activity on LFZ is documented by deformation of sediments dated at 13Ka (OSL) at Cape Kiti, destruction & stranding 400 m inland from current coastline of the Phoenician harbor of Kition-Bamboula approximately 4,000 years ago, and Holocene deformation at a restraining bend near the northern end of the LFZ. In concert with other geological and geophysical observations, such as the absence of a Benioff zone, absence of a volcanic arc & related back arc basin, other documented onshore strike-slip faults of Quaternary age, abundance of strike-slip structures (positive and negative flower structures) identified offshore by geophysical methods, and offshore earthquake focal mechanism resolutions, the LFZ data are consistent with a restraining bend model for the Anatolian-African plate boundary south of Cyprus.