Linkage between chemical erosion and human-induced vegetation pattern during the late Holocene period

Geochemistry of marine sediments serves as a reliable proxy for past continental erosion patterns. Available studies on paleo-erosion although have evaluated the impact of natural factors (climate, vegetation, basin slopes) on erosion rates, the impact of anthropogenic forces on the land surface processes has received limited attention. Recognizing this, major and trace elemental compositions of a sediment core (SSK40/GC06) from the eastern Arabian Sea have been investigated to reconstruct the temporal change in erosional pattern, if any, during the late Holocene period. The chronology of the core has been established using the AMS-¹⁴C age of foraminifera samples. The SSK40/GC06 sediments are mostly clayey to silty in nature, with minimal change in size with depth. Depth profiles of Al-normalized elemental ratios and patterns of rare earth elements point to an insignificant change in relative sediment contributions from the major provenances. In contrast, temporal trends of multiple weathering indices show a significant increase in chemical erosion since ~ 1600 yr BP to the present. Past climatic and sedimentary records show no major change in the southwest monsoon regime during this period. However, existing studies based on sedimentary records from peninsular India show a synchronous rise in the C4 vegetation, which possibly is linked to human-induced agricultural practices. This increase of C4 vegetation with shallow root systems may erode young soils more efficiently, which in turn expose fresh minerals for chemical weathering in basins. The observed trends, along with available past vegetation records, show a strong linkage between chemical erosion and anthropogenic activity.