Early Cretaceous Calcareous Organic-Rich Source Rocks in the Northern Arabian Platform: Paleoceanographic Reconstruction during the Drowning of a Siliciclastic Shelf

Abstract

Barremian-Aptian sedimentary successions along the northern Arabian margin have been described as a transition from a siliciclastic to a carbonate-dominated marine environment, deposited upon a low-relief shelf or platform formed as a consequence of continuous regional subsidence. A long (360 m) core from northern Israel offers a unique look at this transition, providing valuable insights for the palaeoceanography, geometry and ventilation conditions that lead to Oceanic Anoxic Event 1 (OAE1) in this region. Results from high-resolution elemental, mineralogical, sedimentological and petrophysical analyses carried out revealed the emplacement of abundant mass-transport deposits (MTDs) during the Late Barremian and the Aptian. These episodes are accompanied by a high TOC background sediment (up to 32% in the Barremian) and organic matter reworking. The scarcity or absence of bioturbation in the disturbed sequences provides a hint to the sediment/water interface conditions. However, a decrease in sulphur and iron occurring at the contact between the shales and some MTDs is explained as increased oxic conditions at the sediment-water interface as a result of turbulence and mixing associated with the descending sediment masses. Such recurrent events ventilation of the low-energy basinal environment during the Late Barremian and Aptian, predate the wide-scale establishment of OAE1 in the northern Arabian margin. Moreover, the identification of coarse-grained MTDs within deep-water calcareous sediments indicates a much steeper gradient of the northern Arabian margin, challenging previous studies.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018