麻豆传媒

Regional mapping of the distribution, style, and thickness of acoustic facies within a herein established seismic-stratigraphic framework provides new insight in the Late Cenozoic sedimentation history of the Labrador Sea. Four widespread reflecting horizons: Ra, Rb, Rc and Rd, are defined and traced throughout the deeper portion of the basin (in water depths greater than 2500 m) and into the adjacent continental margins. Correlation to deep-water wells DSDP Site 113 and ODP Site 646 indicate approximate ages of late Early Pliocene, early Late Pliocene, late(?)-mid(?)-to-late Late Pliocene and Pleistocene for Rd, Rc, Rb, and Ra respectively. Rapid build up of Eirik Ridge, Hamilton Spur, and a previously undefined sediment drift beneath the southern Labrador Rise occurred during a brief period of intensified bottom circulation in the Mid Pliocene, prior to the onset of widespread continental glaciation. Bottom circulation declined during the Late Pliocene, probably in response to reduced bottom water formation in an ice-covered Norwegian Sea. A previously undefined channel heading off Godthaab, transported turbidites into the Labrador Basin throughout the Pliocene, but reached its zenith during the Late Pliocene at a time of worldwide sea-level lowering. A late Late Pliocene-Early Pleistocene influx of turbidites from off Hudson Strait may indicate the onset of continental glaciation in the eastern Canadian Arctic. Pronounced shelf edge progradation and contemporaneous development of a complex pattern of deep-sea channels, including NAMOC, mark the initial advance of continental ice sheets across the Labrador Shelf in the Mid-Late Pleistocene.

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Supervisor: D. J. W. Piper

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