| dc.description.abstract | In order to determine how sediment transport and alteration processes change the composition of sediment relative to source rock, Icelandic, basaltic fluvial and aeolian sediments were analyzed from the Þórisjökull glacial outwash, a mineral dominated sand field, and Jökulsá á Fjöllum fluvial system, a glass dominated field. These areas were investigated as an analog to early Mars, which is thought to have an active hydrologic and sedimentary system involving glacial, fluvial, and aeolian processes in a basaltic landscape. µXRF element maps, geochemical data, grain size, and thin sections were used to characterize how sediment changes through different grain sizes, environments, and increasing distance from the source.
Sedimentologic results showed the 2021 sediments were finer and more angular than 2019 sediments. Geochemical data revealed that grain size and distance from source were primary factors affecting composition and environment of deposition was secondary. Increased transport distance increased range for geochemical oxide results, yet trends could still be seen in a short distance. FeO and MnO increased with increasing grain size, while SiO2, MgO and CaO decreased with grain size. Other oxides in this study experienced lesser trends than these. The 2021 area contained increased amounts of TiO2 compared to the 2019 area indicating a glassier source material. The 2021 area also contained larger ranges for weight percent oxides in sediments than the 2019 area indicating more geochemical variation. The µXRF element maps and thin sections detected multimineralic grains in the coarser grain sizes and the enrichment of monomineralic in finer grain sizes yet was not useful for detecting geochemical trends through a transect. Our results show that µXRF on loose sediment for specific use cases can provide valuable geochemical information on both Earth and Mars. | |
