Lithofacies evidence for the Cretaceous-Paleogene sedimentary history of Eratosthenes Seamount, Eastern Mediterranean, in its regional tectonic context (Sites 966 and 967)
Robertson, Alastair H F
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Drilling during Leg 160 penetrated an Early–Late Cretaceous and early Oligocene succession of carbonates in Hole 967E, beneath the lower northern slope of Eratosthenes Seamount. Middle Eocene pelagic carbonates were also recovered in Hole 966F, beneath the plateau area of the seamount. The base of the succession at Site 967 comprises shallow-water limestones, including coral and calcareous red algae, and occasional large foraminifers, that are interpreted as accumulations in a lagoonal setting within a carbonate platform. Neritic sedimentation ended in the upper Aptian (Lower Cretaceous) and was followed by an Upper Cretaceous pelagic carbonate succession that spans the interval from upper Cenomanian to Maastrichtian. Upper Cretaceous pelagic carbonates are locally organic rich and contain common replacement chert. In Hole 967E, Maastrichtian pelagic carbonates are unconformably overlain by lithologically similar chalks of early Oligocene age, with evidence of extensive reworking of older taxa. Minor tectonic instability is indicated by the presence of syndepositional neptunian dikes and fissures. In Hole 966F, middle Eocene pelagic chalks include reworked biota, chert, and organic-rich layers. The Eratosthenes Upper Cretaceous and Paleogene bathyal carbonates accumulated on a relatively level, submerged platform, isolated from terrigenous or gravity input. The transition from a shallow, carbonate platform to a bathyal setting (Turonian or earlier), took place before submergence of carbonate platforms in the Levant (in the Coniacian). Upper Cretaceous deposition on Eratosthenes is interpreted to have taken place seawards of a zone of high biogenic productivity that affected the Levant continental margin. Eratosthenes was also located well south of the zone of ophiolite genesis and tectonic displacement in the Upper Cretaceous. Overall, the Cretaceous and Paleogene carbonates of Eratosthenes are consistent with accumulation on an initially shallow, then submerged, carbonate platform isolated within a southern branch of the Neotethyan ocean, adjacent to the North African continental margin.