Fluvio-Sedimentary Responses to Late Quaternary Climate Change in the Lower Latitudes

Under changing climate and the varying strength of monsoon systems, the hydrology of humid low-latitude rivers has varied dramatically during the Late Quaternary. As a consequence, fluvial systems throughout the tropics and subtropics have displayed acute responses, such as orders of magnitude variation in discharge; several fold changes in sediment load; 10's of meters of floodplain incision and aggradation; shifting sediment source areas; and altered sediment mineralogy and geochemistry. Many of these responses can be correlated across several continents, indicating global-scale effects. Altogether, common response patterns are emerging from these low-latitude dispersal systems and suggest that a coherent long-term record of fluviosedimentary behavior can be reconstructed. Furthermore, such patterns may better establish climate records as proxies for past fluvial-sediment discharge to the margin. This is significant, because tropical and subtropical rivers support the world's highest erosion and weathering rates and presently account for >75% of all riverine sediment delivered to the world's continental margins. However, many questions related to the magnitude, impacts, and preservation of such climate-induced responses remain, despite the apparent similarity and synchronicity of events.