Weathering and Global Denudation

TLDR

Sediment yield is negatively correlated with weathering history (CIA), with equilibrium denudation regions showing a clear control while nonequilibrium regions exhibit scattered relationships. Low yields arise from moderated erosion or incorporation of unweathered glacial debris, whereas high yields result from human‑induced accelerated erosion such as cultivation and land use. These processes markedly affect global sediment discharge, with pre‑human discharge estimated at 12.6 × 10¹⁵ g yr⁻¹, roughly 60 % of today’s level.

Abstract

A negative correlation between sediment yield and weathering history, as measured by the chemical alteration (CIA) of the suspended sediment, is observed for many of the world's major rivers and other regions of denudation. The weathering history is a first-order control on the sediment yield of such areas, termed equilibrium denudation regions. For other areas, data scatter with either apparent increases or decreases of sediment yield for given CIA values. These areas are termed nonequilibrium denudation regions. Low sediment yields can be attributed to moderated erosion (either natural or human induced) and/or the incorporation of unweathered glacial debris. Accelerated erosion, resulting in high sediment yield, is primarily human-induced and results from cultivation and other land use. Each of these effects has a profound influence on global sediment discharge from the continents. Pre-human suspended sediment discharge from the continents is estimated to be $$12.6 \times 10^{15} g/yr$$ or about 0.6 the present discharge.