Provenance of late Quaternary loess along the Middle and Lower Danube River, Europe

Thesis

Loess-palaeosol sequences along the Danube River are often the only Quaternary environmental and climatic archive spanning the whole last glacial-interglacial (and beyond) in Eastern and Central Europe. Despite long standing loess research their origins and formation processes are still debated. This thesis aims to fill this gap by investigating timing of deposition and provenance of loess deposits along the Danube River. The analysis pivots around geochemistry and geochronology.

Application of the latest luminescence dating protocols provides a basis for answering questions regarding the timing and rate of sediment accumulation, while detrital zircon U-Pb dating and Hf isotopes were utilised to better understand the source(s) of loess deposits along the Danube River. The timing of deposition and sediment origins provides insights into depositional history and sediment transport pathways.

The luminescence dating supports previous suggestions that loess deposits are not continuous and likely contain hiatuses. The hiatuses may not be spatially extensive, therefore high-resolution sampling approaches are critical to better understand these deposits. Further spatial analysis of mass accumulation rates shows deposition is not constant over time but varies greatly. Importantly comparison of multiple sites indicates that activity periods are not uniform spatially but rather site specific.

Provenance results show the Danube’s alluvium is the immediate geomorphological source of sediment for the loess profiles, indicating that sediment is predominantly transported over short distances. Rivers remain a crucial component of the source-to-sink loess model, though this research goes a step further showing that they are responsible for homogenising sediment, e.g. Danube sits on a mixing line between the Alp draining Sava and the Carpathian draining Tisza. Moreover, the results suggest that the Alps, Bohemian Massif and Carpathians are the main sediment proto-sources. However, for the first-time the importance of smaller not extensively glaciated mountain belts e.g. Dinaric and Balkan Mountains is shown which questions glacial action as a crucial sediment producing mechanism. Finally, the results suggest that sites along the Danube share sources and that sediment source remained unchanged over the Quaternary timescale.

Authors: Fenn, K

• DOI: 10.5287/ora-kqmxgzbrd
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Geochronology; Hf isotopes; MARs; Loess; Provenance; Luminescence; Zircons; U-Pb dating
• Subjects: Geology; Geography