Fuerte River floods, an overlooked source of terrigenous sediment to the Gulf of California

• Unusual sedimentary facies as been described as clastic mud beds.
• Terrigenous deposits are related to discrete historical climatic events.
• Fuerte River floods contribute significantly to terrigenous delivery to the Gulf of California.

Sediments deposited on the southeastern continental shelf of the Gulf of California, near the Fuerte River mouth, have been investigated using sediment XRF elemental composition, magnetic parameter and radiogenic element activities, and imply lithogenic elements as a promising proxy for terrigenous input and river discharge. Clastic mud beds are observed in the sediment core DIPALV-C33. These layers are massively bedded and characterized by coarser terrigenous sediment than typically observed in the Gulf of California. Based on this distinct lithology observed recurrently in the Fuerte River mouth region, we suggest these beds form during flooding events of the river. Comparing our results with instrumental data, we associate these unusual beds with Hurricane Lidia in October 1981 and a strong winter storm in January 1944. Elemental ratios Zr/Rb and K/Ti in the sediment core are strongly correlated with the lithologic changes, supporting their use as flood event proxies. Finally, we show that the three events observed account for 15% of the cumulative sediment deposited in DIPALV-C33 locations during the last two centuries, suggesting that in addition of seasonal eolian supply, floods events may contribute significantly to terrigenous delivery to the Gulf of California.