Decoding the signals of sediment weathering: Toward a quantitative approach

Abstract

In order to better interpret the signals of weathering intensity recorded in terrigenous sediment archives, it is essential to appropriately assess the effects of hydrodynamic sorting and sedimentary recycling. To achieve this, we utilized a compiled dataset of major element geochemistry of river sediments from East Asia to develop a quantitative index for evaluating the extent of quartz enrichment related to hydrodynamic sorting and sedimentary recycling. By leveraging the trend of present-cycle weathering products in the CIA-WIP diagram, we proposed the chemical index of quartz-enrichmen (CIQ), which can assess the hydrodynamic sorting and sedimentary recycling effects on the present-cycle weathering products. The CIQ vs. CIA/WIP diagram clearly discriminates the influences of weathering intensity, hydrodynamic sorting and sedimentary recycling on bulk sediment chemistry. In this diagram, representative sediments for the present-cycle weathering product typically cluster around CIQ = 0, and the CIA/WIP (or CIA) of which reflect the recorded weathering intensity. The application of our method to depth profiles from the world's largest rivers provides evidence supporting the utilization of sedimentary records to reconstruct paleo-weathering intensity. This study provides a practical and efficient approach to assess whether or to what extent siliciclastic sediments can accurately depict the present-cycle weathering products. This sheds new light on the quantitative deciphering of weathering intensity signals in terrestrial clastic sediments.