Abstract: 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.

Abstract Potassium-argon dating indicates two episodes of basaltic magmatism in south eastern Turkey at c. 19–15 and c. 2.3–0.6 Ma. Each produced olivine-titanaugite basalts, whose chemical compositions are difficult to classify using any conventional model in both the Anatolian continental fragment and the Arabian Platform. It is proposed here that both episodes of volcanism, and the associated crustal thickening and surface uplift, result from heating of the mantle lithosphere by crustal thickening caused by inflow of plastic lower crust from adjoining regions. Thus, although this study region has remained in a plate boundary zone for tens of millions of years, its volcanism has no direct relationship to local plate motions. It is suggested instead that both episodes of volcanism are the result of loading effects caused by glacial to interglacial sea-level variations, which will cause net flow of lower crust from beneath the offshore shelf to beneath the land: the moderate glaciations of Antarctica which began in the Early-Middle Miocene, and the more intense lowland glaciations of the northern hemisphere which began around c. 2.5 Ma.