Sedimentary responses to the cross-shelf transport of terrigenous material on the East China Sea continental shelf

Abstract

Sedimentary responses to the cross-shelf transport on the East China Sea continental shelf are ascertained based on analyses of the sediment grain size and detrital mineral components of surficial sediments. Sedimentological data show that fine-grained sediments can be transported across the continental shelf and have formed a tongue-shaped zone with an axis located near 29°N that extends from the coast to 124°40′E or beyond. The sediments in this tongue-shaped zone are rich in very fine silt and clay, as are the dominant sediment fractions discharged by the modern Yangtze River indicating a modern terrigenous source. Sediment with grain sizes 7–9 Φ is the main fraction that is transported across the continental shelf. In contrast to the regions in the same longitude, in the tongue-shaped zone the relatively low heavy mineral content, high schistose mineral content and high dolomite content and the mixture of fresh and weathered minerals show that modern Yangtze River sediment has been widely transported to this region. Meanwhile, the simultaneous existence of the fine-grained tongue and a coarse-grained area immediately south of the base of the tongue coincident with the nearshore Kuroshio branch current intrusion area indicate that the Kuroshio intrusion plays an important role in triggering the cross-shelf flows.