Drainage response to Arabia-Eurasia collision: Insights from provenance examination of the Cyprian Kythrea flysch (Eastern Mediterranean Basin)

摘要

The Cenozoic geodynamics of the north-eastern Mediterranean Basin have been dominated by the subduction of the African Plate under Eurasia. A trench-parallel crustal-scale thrust system (Misis-Kyrenia Thrust System) dissects the southern margin of the overriding plate and forms the structural grain and surface expression of northern Cyprus. Late Eocene to Miocene flysch of the Kythrea (De?irmenlik) Group is exposed throughout northern Cyprus, both at the hanging-wall and footwall of the thrust system, permitting access to an extensive Cenozoic sedimentary record of the basin. We report the results of a combined examination of detrital zircon and rutile U-Pb geochronology (572 concordant ages), coupled with Th/U ratios, Hf isotopic data and quantitative assessment of grain morphology of detrital zircon from four formations (5 samples) from the Kythrea flysch. These data provide a line of independent evidence for the existence of two different sediment transportation systems that discharged detritus into the basin between the late Eocene and late Miocene. Unique characteristics of each transport system are defined and a sediment unmixing calculation is demonstrated and explained. The first system transported almost exclusively North Gondwana-type, Precambrian-aged detrital zircon sourced from siliciclastic rock units in southern Anatolia. A different drainage system is revealed by the middle to late Miocene flysch sequence that is dominated by Late Cretaceous- Cenozoic-aged detrital zircon, whose age range is consistent with the magmatic episodicity of southeast Anatolia, along the Arabia-Eurasia suture zone. Deposition of these late Miocene strata took place thereupon closure of the Tethyan Seaway and African-Eurasian faunal exchange, and overlap in time with a pronounced uplift of eastern Anatolia. Our analytical data indicate the onset of prominent suture-parallel sediment transport from the collision zone of south-eastern Anatolia into the Kyrenia Range of norther