9-7 Tracking Sediment Mixing of Southern California Rivers in the San Pedro and Oceanside Littoral Cells

Session: Sedimentary Systems and Provenance in the Western Cordillera (Posters)

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In many river and beach ecosystems, sediment transfer has been affected by human modification. The creation of infrastructure continues to create problems, leading to the changing of the natural key processes of the Earth’s ecosystems. Namely the reduction of sediment reaching the coast will negatively impact coastal resilience to rising sea level induced erosion. This research aims to investigate how human infrastructure has impacted the rivers’ capability to transfer sediment in the Southern California basins to coastal regions and subsequently deposit in submarine canyons. This will be accomplished through examining the composition of the coastal deposits before significant human influence to identify key shifts in sediment transport over time. In this work we compile initial detrital zircon and apatite U-Pb results from the Los Angeles, Orange, and San Diego County river systems, as well as the associated beaches these rivers terminate. We will integrate geographical information systems to study the watersheds of these river systems and make watershed models of erosion and sediment transport to the coastal regions. These new data will serve as a modern baseline to compare against offshore samples that we expect to record in the Southern California landscape before significant agriculture, irrigation, and development.  We will also take advantage of the U-Pb results to generate a robust detrital zircon dataset that can shed light on ancient magmatic arc processes in the Southern California and Peninsular Ranges Batholiths, which is essential to reconstructing the history of Baja California’s tectonics. 

Geological Society of America Abstracts with Programs. Vol. 58, No. 3, 2026

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