Environmental signals recorded in modern sediments of tropical South American rivers

Abstract

Archives like marine sediment cores register environmental conditions through proxies in an indirect way. Thus, the appropriate reconstruction of paleoenvironmental changes rely on understanding the relationship between the aimed original environmental signal and the analyzed proxy. Here we will (i) determine how environmental signals are recorded in modern fluvial sediments, and (ii) assess possible seasonal changes in environmental signals transported by fluvial sediments of the main tributaries of the Amazon River drainage basin. Our focus relies on determining the source of detrital sediments, the amount of rainfall and the main types of vegetation. Therefore, we will sample and analyze the following proxies in modern fluvial sediments from a carefully selected suite of fluvial stations from tropical South America: (i) neodymium isotopic composition of the detrital fraction (a proxy for the source of detrital sediments); and (ii) stable hydrogen and carbon isotopic composition of plant-wax-derived lipids (proxies for the amount of rainfall and the main types of vegetation, respectively). By doing this, we will provide an in-depth understanding about the way environmental signals are recorded in modern sediments and transported by tropical South American rivers, improving tropical South American paleoenvironmental reconstructions based on marine sediment cores.