Quaternary hemipelagic sedimentation in the basins flanking the Solomon Islands volcanic arc

Quaternary sediments in the Woodlark Basin and New Georgia Sound, adjacent to the Solomon Islands volcanic arc, are hemipelagic. They consist of mixtures of clay minerals, calcareous plankton (foraminifera, coccoliths, and pteropods), and sand- and silt-sized volcanic debris. Variations in sediment composition are related primarily to distance from land (the source of volcanic components), water depth (because of the Aragonite and Calcite Compensation Depths), and bathymetric isolation. Much of the sedimentary debris is delivered to the basin by turbidity currents and other mass movements; little material is supplied by ash fall. Sedimentation rates appear to exceed 3 cm/1,000 years in New Georgia Sound, and range from 2 to 4.5 cm/1,000 years in the Woodlark Basin.