Linking Surface and Tectonic Processes to Marine Sedimentary Archives in the Amazon River-Fan System Through the Integration of Detrital Geochronology, and Chemical, and Physical Sedimentology

Source-to-Sink (S2S) systems offer insights into climate-surface interactions, revealing the interplay between climate change, weathering, erosion, and tectonics. The Amazon S2S system transfers significant amounts of sediment to the equatorial Atlantic Ocean where the offshore submarine fan is a repository of material transferred from ~6 million km2 of the South American continent over multi-million-year timescales. Chemical signatures in marine sediment from Neogene offshore basins have improved our understanding of the evolution of the Amazon drainage system since the Miocene, while detrital low-temperature geo-thermochronology of Pleistocene detritus has revealed the timing of major tectonic cycles experienced by the hinterland over tens to hundreds of millions of years. Here, we summarize existing and new detrital geo-thermochronologic data sets (zircon U–Th/He and fission track dating), and present new whole rock XRF and ICP-AES/MS (125 samples) and quantitative grain size analyses (40 samples) of fine-grained sediment recovered from the upper 450 m of the Amazon deep-sea fan (ODP Sites 931, 936, and 946). These geochemical data reveal provenance and paleo-weathering trends with potential climatic controls vs. grain size controls. When integrated with low-temperature detrital geo-thermochronology, these geochemical methods help paint a more complete picture of S2S system behavior that includes multi-millennial signals of changing boundary conditions recorded in the fine-grained sediment fraction, with implications for the study of other systems.