Small mounded contourite drifts associated with deep-water coral banks, Porcupine Seabight, NE Atlantic Ocean
D. Van Rooij, D. Blamart, M. Kozachenko, J.-P. Henriet, 2007. "Small mounded contourite drifts associated with deep-water coral banks, Porcupine Seabight, NE Atlantic Ocean", Economic and Palaeoceanographic Significance of Contourite Deposits, A. R. Viana, M. Rebesco
Download citation file:
Numerous studies on sediment drifts have demonstrated a close interaction between sea-bed morphology, palaeoceanography, sediment supply and climate. Contourites have been reported in areas along continental margins directly influenced by the effect of intensive deep-water currents from the global conveyor belt. In this paper, we report the occurrence of a small-scale confined contourite drift from Porcupine Seabight, SW of Ireland, and its association with a province of coral banks. The Porcupine Basin is a relatively shallow, semi-enclosed basin characterized by the presence of cold-water coral bank provinces. These coral banks are often associated to a strong northward-flowing bottom current, created and steered by a complex interaction of the water mass characteristics, tidal influences and sea-bed morphology. Very high-resolution seismic stratigraphy allowed the identification of a small mounded drift, located between a depression created by (1) an irregular palaeotopography caused by a vigorous Late Pliocene erosion event and (2) a north-south alignment of coral banks. Core MD99-2327, taken on the flank of this drift mound, shows the variability of the bottom currents. Sortable silt data show several periods of bottom-current enhancement, which may be linked with warmer periods and an inferred influx of Mediterranean Outflow Water. The glacial part of the core has been interpreted as a muddy contourite with a high content of ice-rafted debris. The lower part of the core is a deep-water massive contourite sand resembling the present-day sea-floor sediments.
Figures & Tables
There has lately been a growth in the number and level of studies of contourite deposits. Most recent studies of contourites have two major lines of interest. One, propelled by the oil industry's continuous move into increasingly deep waters, concerns their economic significance. The other involves the stratigraphic/palaeoceanographic record of ocean circulation changes imprinted on contourite deposits that can be a key to understanding better the climate-ocean connection. The application of many different theoretical, experimental and empirical resources provided by geophysics, sedimentology, geochemistry, petrology, scale modeling and field geology are used in the 16 papers of this volume, proposing answers to those two main aspects. The papers are subdivided into two major categories (economic interest and stratigraphic/palaeoceanographic significance), with case studies ranging from well-documented drifts to new examples of modern and fossil series, involving a large diversity of geographic and physiographic scenarios worldwide.