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.
Can climatic signals be discerned in a deep-water sink?: An answer from the Pearl River source-to-sink sediment-routing system
Chenglin Gong, Michael D. Blum, Yingmin Wang, Changsong Lin, Qiang Xu; Can climatic signals be discerned in a deep-water sink?: An answer from the Pearl River source-to-sink sediment-routing system. GSA Bulletin doi: https://doi.org/10.1130/B31578.1
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