Sediment Dynamics and Monsoon Influences in Coastal Regions

Coastal sediment dynamics arise from the interplay of river discharge, waves, tides and monsoon-driven precipitation. Riverine sediments deliver terrigenous material to deltas and continental shelves, where hydrodynamic processes—longshore currents, contour currents and gravity flows—redistribute particles across a range of depths. Seasonal and interannual variations in monsoon intensity modulate erosion rates in source areas, chemical weathering intensity and sediment supply, leaving distinct mineralogical and geochemical signatures in coastal deposits. Sediment cores thus serve as archives of past monsoon behaviour, capturing shifts associated with abrupt climatic events, sea-level change and anthropogenic modification of catchments. Understanding these mechanisms is crucial for predicting coastal resilience, managing erosion hazards and informing sustainable development in monsoon-affected regions worldwide.

Research from Nature Portfolio

Recent studies have employed high-resolution sediment cores from the northwest South China Sea to map changes in grain size, clay mineralogy and major element geochemistry over the past 13 000 years. Illite crystallinity and smectite/(illite + chlorite) ratios emerged as reliable proxies for monsoon-driven chemical weathering and terrigenous input, revealing millennial-scale shifts corresponding to Younger Dryas, Bond events and Holocene monsoon intensifications. Earlier foundational work on clay assemblages extended back 400 ka, demonstrating orbital-scale controls of northern hemisphere summer insolation on weathering intensity and provenance. Together, these investigations clarify the coupling between monsoon variability, river discharge and sediment deposition in coastal settings.

Sediment Dynamics and Monsoon Influences in Coastal Regions publication trend

The graph below shows the total number of articles in sediment dynamics and monsoon influences in coastal regions across all publications each year (not limited to Nature Index journals).

Technical terms

Illite crystallinity index: A measure of ordered stacking of illite layers, acting as a proxy for chemical weathering intensity in source areas.

Smectite/(illite + chlorite) ratio: A clay mineral proxy sensitive to monsoon-driven weathering and precipitation variability.

Contour currents: Alongslope ocean currents that transport sediments parallel to bathymetric contours, influencing lateral dispersal on continental margins.

Chemical index of alteration (CIA): A geochemical ratio (Al₂O₃/(Al₂O₃+CaO+Na₂O+K₂O)) indicating the extent of chemical weathering in sediments.

References

1. Paleoenvironmental changes in the coastal zone of the northwest South China Sea during the last 13 kyr. Scientific Reports (2023).
2. Fate of sediments delivered to the sea by Asian large rivers: Long-distance transport and formation of remote alongshore clinothems. The Sedimentary Record (2009).
3. Clay mineralogical and geochemical proxies of the East Asian summer monsoon evolution in the South China Sea during Late Quaternary. Scientific Reports (2017).
4. Spatiotemporal patterns of sediment deposition on the northern slope of the South China Sea in the last 150,000 years. Journal of Palaeogeography (2021).
5. Multi—Proxy Reconstructions of Climate Change and Human Impacts Over the Past 7000 Years From an Archive of Continental Shelf Sediments off Eastern Hainan Island, China. Frontiers in Earth Science (2021).
6. Sedimentary Responses to Climate Changes and Human Activities Over the Past 7400 Years in the Western Sunda Shelf. Frontiers in Earth Science (2021).