Neotectonic and volcanic characteristics of the Karasu fault zone (Anatolia, Turkey): The transition zone between the Dead Sea transform and the EastAnatolian fault zone

The Karasu Rift (Antakya province, SE Turkey) has developed between east-di pping, NNE-striking faults of the Karasu fault zone, which define the weste rn margin of the rift and west-dipping, N-S to N20 degrees -30 degreesE-str iking faults of Dead Sea Transform fault zone (DST) in the central part and eastern margin of the rift. The strand of the Karasu fault zone that bound s the basin from west forms a linkage zone between the DST and the East Ana tolian fault zone (EAFZ). The greater vertical offset on the western margin faults relative to the eastern ones indicates asymmetrical evolution of th e rift as implied by the higher escarpments and accumulation of extensive, thick alluvial fans on the western margins of the rift. The thickness of th e Quaternary sedimentary fill is more than 465 m, with elastic sediments in tercalated with basaltic lavas. The Quaternary alkali basaltic volcanism ac companied fluvial to lacustrine sedimentation between 1.57 +/- 0.08 and 0.0 5 +/- 0.03 Ma. The faults are left-lateral oblique-slip faults as indicated by left-stepping faulting patterns, slip-lineation data and left-laterally offset lava flows and stream channels along the Karasu fault zone. At Haci lar village, an offset lava flow, dated to 0.08 +/- 0.06 Ma, indicates a ra te of left-lateral oblique slip of approximately 4.1 mm.year(-1). Overall, the Karasu Rift is an asymmetrical transtensional basin, which has develope d between seismically active splays of the left-lateral DST and the left-la teral oblique slip Karasu fault zone during the neotectonic period. (C) 200 1 Editions scientifiques et medicales Elsevier SAS.