Abstract

Using integrated two- and three-dimensional seismic and shallow borehole data from the Pearl River source-to-sink system, this study demonstrates that submarine fan deposition records climatic signals of Asian monsoons and the mid-Pleistocene climate transition, but with a lag time of 100 k.y., providing new tools to predict the past climate and important insights in source-to-sink context. Specifically, cooler and drier climates during weakened monsoons from marine oxygen isotope stages (MIS) 20 to 12 (814–478 ka), with reduced global ice volumes, led to decreased overall sediment supply and reduced amplitudes of sea-level change, which, in turn, decreased cross-shelf transit distances and gave rise to much sandier prograding intraslope fans. Warmer and wetter strengthened monsoons from MIS 12 to 1 (478 ka to recent), with larger global ice volumes and corresponding amplitudes of sea-level change, in contrast, led to increased overall sediment supply but served to increase cross-shelf transit distances, resulting in much muddier retrograding intraslope fans. Climatic changes in source areas, coupled with global climate and sea-level changes, therefore modulated the lithological characteristics of terminal sinks in the Pearl River source-to-sink system. High-frequency (43 k.y.) and low-amplitude sea-level changes (mean value of sea level = –55.8 m, with the standard deviation of ±24.2 m) during the mid-Pleistocene climate transition caused shorelines to more frequently reside proximal enough to the shelf edge to deliver coarse sediments to deep-water areas, leading to higher sediment delivery rates (Rs) of 5–15 km/m.y. and larger prograding intraslope submarine fans. Lower-frequency (100 k.y.) and higher-amplitude sea-level fluctuations (mean value of sea level = –62.7 m, with the standard deviation of ±33.2 m) after the mid-Pleistocene climate transition, in contrast, prevented shorelines from staying close enough to the shelf edge to continuously deliver coarse sediments to deep water, resulting in lower Rs of 4–8 km/m.y. and smaller retrograding intraslope submarine fans. Climatically controlled eustatic fluctuations, thus, determined sediment delivery rates and volumes of the terminus of source-to-sink systems.

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