Sedimentology and geochemistry of the recent sediments of the river system on Hurd Peninsula, Livingston Island, Antarctica

Abstract

Seasonal ephemeral stream systems on Livingston Island (South Shetland Islands) serve as vital natural laboratories for elucidating sedimentary processes in maritime Antarctic environments. This study presents the first comprehensive petrographic and geochemical records of terrestrial surface sediments in this region to constrain their provenance and sedimentary evolution. Micromorphological analyses reveal that these sediments comprise predominantly poorly to moderately sorted, angular to sub‐angular particles ranging from clay to sand, indicative of highly restricted transport. Geochemical proxies, including low Th/U and distinct Zr/Sc and Th/Sc ratios, strongly corroborate a first‐cycle sedimentary assemblage with negligible evidence of recycling or hydrodynamic sorting. Although the sediments generally exhibit the low chemical weathering indices typical of cold climates, localised chemical alteration is evidenced by Large Ion Lithophile Element depletion (Cs, Rb, Ba, K) and the presence of kaolinite. This alteration is attributed to the distinctively humid microclimates characteristic of Maritime Antarctica. Furthermore, elemental signatures (Co/Th, Eu/Eu*, La/YbN, Hf, Nd and Y) suggest derivation from a composite mixture of the island's bedrock. Major and trace element geochemistry, coupled with multidimensional discriminant function analyses, demonstrates that the contemporary sediment budget is governed principally by the physical disintegration of Mesozoic–Cenozoic South Shetland magmatic arc rocks—most notably the Miers Bluff Formation and associated intrusive suites. However, the system's polygenetic framework is highlighted by a subtle geochemical shift towards rift‐related domains, capturing a subordinate physical influx of Quaternary tephra superimposed onto the foundational arc‐crust signature. Ultimately, these integrated geochemical and micromorphological insights provide a critical baseline for decoding source‐to‐sink sedimentary dynamics in maritime Antarctica, offering a broader window into how high‐latitude depositional systems respond to modern polar climate shifts.