Sea-level controls on terrigenous sediment input to deep water of the Pearl River margin since the last glacial maximum

Glacio-eustatic sea-level changes since the Last Glacial Maximum (LGM) have been frequently regarded as the primary driver of terrigenous input to deep-water settings of marginal sea basins. However, on those continental margins where shelf edges lie at water depths farther exceeding 120 m, whether and how eustatic sea-level changes since the LGM have controlled terrigenous sediment input to deep water remains a topic of considerable interest. Taking the Pearl River margin that has a shelf edge with average water depth of 250 m as the study area, we use the depositional records of two piston cores on the head and mouth of a submarine canyon to reconstruct the history of terrigenous input to deep water since the LGM. We then relate the variations of terrigenous input to the contemporary eustatic sea-level changes to examine the details of the role of sea-level changes on terrigenous input. The results indicate that since the LGM there was a three-stage temporal evolution of terrigenous input to deep water on the Pearl River margin. During glacial, deglacial, and interglacial periods, terrigenous input were respectively high, decreasing, and low, correlating well with sea-level lowstands, sea-level rising, and sea-level highstands. Such tight coupling strongly suggests that glacio-eustatic sea-level changes since the LGM could still control terrigenous input to deep water on the Pearl River margin. Specifically, after the LGM, the first rapid sea-level rise, occurred in the periods of Heinrich Stadial 1 (HS1) and Bølling-Allerød (B-A), dramatically inundated the shelf, shifted the shoreline landward and thus, caused a millennial-scale drop of terrigenous input. Within the interglacial period, the sea level had risen almost to its present level and remained relatively stable, during which fluctuations in East Asian Monsoon (EAM) might have an influence on terrigenous input. Therefore, within the interglacial period, terrigenous input, though generally having low levels, showed a slight fluctuation correlated well with the changes of monsoonal climates. This study deepens our knowledge on the fundamental role of sea-level changes in sediment dispersal systems and provides implications for understanding deep-sea dynamics, especially within the context of a continental margin where shelf edges are found at much greater water depths and climatic conditions are rapidly changing.