Rift Tectonics of the Polis Extensional Graben, N.W. Cyprus, and Associated Traps

Lester C. Ward

The Polis extensional graben, northwest Cyprus, is located west of the Troodos ophiolite massif and east of the Akamas Peninsula. It outcrops 35 km onland before trending offshore into the Cilician basin. From field studies, geophysical and seismic data, and NASA shuttle photos, the graben is seen to be asymmetric in cross section, trending north-northwest-south-southeast, and is of Miocene-Holocene age. The graben is delineated by planar and listric normal faults (oriented 160°/340°) which dip toward the axis of the graben and have dip-slip motion from slickenside studies. The Polis graben evolved at the end of late Miocene time in response to passive rifting, as evidenced by extensional boudinage, horizontal stylolites, and multiple unconformities in older pre upper Miocene formations. Rifting occurred in multiple phases which commenced in the north and propagated southward. These produced subsidence, preserving pre-graben traps from erosion. The graben is transected by major transverse faults which segment it into separate structural domains that control differential tilt and subsidence of blocks in the axis of the graben. Lithofacies analysis shows pre-graben traps include reefs and deposits formed in response to gravity and mass-flow events. Graben-fill sequences consist of coarse clastics at the base, deposited in braided-stream and alluvial-fan environments, superseded by deep-water facies, due to the Pliocene transgression, which include graded sands, turbidites, and mass-flow deposits and fan deltas. Traps are structured and tilted to p oduce rollover anticlines and monoclinal folds.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.