The Sawqirah contourite drift system in the Arabian Sea (NW Indian Ocean): A case study of interactions between margin reactivation and contouritic processes

摘要

The relationships between oceanic circulation in the Arabian Sea and Late Cenozoic climate changes, including variations in monsoon intensity at the million year time-scale, remain poorly investigated. Using multibeam and seismic data, we provide the first description of a contourite drift in the Arabian Sea, along the south-eastern Oman margin. This contourite drift is referred as the "Sawqirah Contourite Drift System". Late Miocene reactivation of the south-eastern Oman margin resulted in the formation of a complex anticline system, which shaped the seafloor topography above which the Sawqirah Drift subsequently developed. The drift resulted from the circulation of bottom currents within the North Intermediate Indian Water. Major seismic unconformities identified within the Sawqirah Drift were tied to Ocean Drilling Program (ODP) drill holes, and allowed defining distinct episodes of drift construction. At least two of these unconformities record reorganizations of the oceanic circulation at similar to 4.5-4.8 Ma and similar to 2.4 Ma. The 4.5-4.8 Ma-old unconformity is coeval with the onset of upwelling of deep and cold waters in the Owen Basin. The 2.4 Ma-old unconformity records a major episode of Indian monsoon intensification (at the million year time scale) over the Arabian Sea, indicating strong coupling between oceanic and atmospheric circulation processes. (C) 2016 Elsevier B.V. All rights reserved.