Students Day: Three Msc/PhD Students and Postdocs present their work

1 - Lea Huber, BSc, Institute of Earth Sciences, Heidelberg University

Expedition to Hess Rise: sampling an oceanic plateau with RV SONNE

Abstract

This summer, the German research vessel  SONNE embarked on a research cruise to Hess Rise, a Large Igneous Province in the northern Pacific Ocean. Two scientists from Heidelberg were on board to investigate the deep sea and recover volcanic rock samples from the seafloor. This talk provides a brief insight into life and scientific work on board from a student’s perspective.

2 - Merit Neibig, BSc, Institute of Earth Sciences, Heidelberg University

Paleocene Island-Arc Rocks from the Eastern Cayman Margin: New Constraints on Tectonic Evolution of the Northwestern Caribbean

Abstract

The northern Caribbean plate boundary is characterized by relative motion between the Caribbean and North American plates, which has been accommodated by strike-slip faults along the widening Cayman Trough since the Eocene. This study investigates the onset of extension and the transition to generation of oceanic crust in this narrow pull-apart basin. Two basalts and six granodiorites dredged from the eastern Cayman margin between Cuba and Jamaica were analyzed using petrography, mineral chemistry, whole-rock major- and trace-element geochemistry, and SIMS zircon U-Pb geochronology. Three granitoids yielded concordant zircon crystallization ages of ∼64 Ma with rare Late Cretaceous inherited zircon cores (69–90 Ma). The rock chemistry of the I-type calc-alkaline granitoids is indicative of subduction-related intra-oceanic island-arc origin. Both age and geochemistry closely resemble those of granitoids from Jamaica and the Northern Nicaraguan Rise but differ significantly from the western Cayman Ridge granitoids’ continental affinity, suggesting two distinct magmatic origins. In terms of early rifting, the eastern Cayman margin granitoids confirm the non-oceanic character of the thinned pre-Eocene basement. However, unlike proposed for this slow-spreading ridge, they show no clear signs of transitional crust. The samples record variable degrees of strain, but despite a complex tectonic history, most exhibit minor deformation. The results presented in this thesis constrain the initial rifting of the Cayman Trough and the tectonic setting shaping its eastern margin.

3 - Estefany Villanueva-García, MSc, Institute of Earth Sciences, Heidelberg University

From rivers to deep-marine systems: coastal sourcing, redistribution and provenance partitioning along an active continental margin, northern Colombia

Abstract

Source-to-sink reconstructions commonly emphasize direct fluvial-to-deep-marine transfer, yet the coastal domain may actively modify provenance signals before offshore delivery. This study investigates how contrasting sediment-routing systems along ~300 km of the northern Colombian Caribbean margin may generate, preserve, or transform provenance signatures across fluvial, coastal, and deep-marine domains. We integrate detrital zircon U–Pb geochronology from ten new coastal samples with bulk and clay mineralogy, grain-size data, and previously published fluvial and offshore provenance records. The high-discharge Magdalena River system produces polymodal zircon age spectra that are consistently preserved from the river through the coastal domain into the Magdalena Canyons System, where Magdalena-derived sources account for 77–85% of the modeled zircon-age signal. In contrast, the Sierra Nevada de Santa Marta (SNSM) coast, characterized by low fluvial supply and bedrock exposed at the shoreline, introduces a distinct Paleogene zircon signal (~51–54 Ma; 84–92%) that cannot be reproduced by available fluvial endmembers and is consistent with erosion of the Santa Marta Batholith. This coastal-sourced signal is subsequently routed through La Aguja Canyon, where SNSM-derived sources dominate (71–76%). Distal offshore samples record contributions from both systems, indicating progressive provenance integration at basin scale. These results demonstrate that the coastal domain can function either as a passive transfer zone preserving upstream provenance or as an active sediment source introducing new signals, depending on the balance between fluvial supply and shoreline source availability. Consequently, provenance deviations in canyon and fan deposits may reflect coastal sourcing rather than drainage reorganization, highlighting the need to incorporate coastal domains in source-to-sink reconstructions.