Doctoral Defense in Earth Sciences - Noemi Löw

Zoom Link:
https://eu01web.zoom.us/j/61049177309

Doctoral candidate:
Noemi Löw

Title of thesis:
Origin and age of the near-rift Fjallgarðar Volcanic Ridge, Northeast Iceland

Opponents:
Dr. Michael Storey, Natural History Museum of Denmark, University of Copenhagen
Dr. Colin Macpherson, Department of Earth Sciences, Durham University

Advisor:
Dr. Sæmundur Ari Halldórsson, Faculty of Earth Sciences, University of Iceland

Other members of the doctoral committee:
Dr. Christoph Beier, professor at the Department of Geosciences and Geography, University of Helsinki
Dr. Simon Matthews, Research Assistant Professor at the Geology Department of the University of Iceland
Dr. Enikő Bali, professor at the Geology Department of the University of Iceland
Dr. Guðmundur Guðfinnsson, Research Associate Professor at the Geology Department of the University of Iceland

Chair of Ceremony:
Dr. Andri Stefánsson, prófessor og deildarforseti Jarðvísindadeildar HÍ

Abstract:
The Fjallgarðar Volcanic Ridge (FVR) is a ~200 km long subglacially erupted volcanic ridge east of and parallel to the Northern Rift Zone in Iceland. Despite its size and prominent geomorphology, its origin and relationship to nearby volcanic systems and rift zone segments remain poorly constrained. This thesis investigates the origin and age of the FVR through an integrated study - petrology, geochemistry, radiogenic and helium isotope characteristics, and 40Ar/39Ar geochronological dating. The results reveal that the FVR was active between ~790 and ~100 ka and erupted exclusively during glacial periods. Two compositionally distinct basalt groups are identified throughout the FVR: a depleted tholeiitic suite and a more enriched suite. The depleted group dominated the early phase of FVR volcanism, where the geochemical and isotopic compositions suggest a clear link to source materials associated with the Icelandic mantle plume. In contrast, the enriched group, which appeared at ~400 ka, preserves geochemical characteristics of the Kverkfjöll volcano, underneath which magmas were stored before being transported laterally through long-distance dyke propagation to the FVR. The trace element and isotope data suggests that the depleted FVR basalt group was likely generated from upwelling of the plume material beneath Central Iceland and transported to the FVR analogously to the magmas from Kverkfjöll. In tandem, the depleted magmas may also have formed beneath a thicker lithospheric lid beneath or east of the FVR after plume-derived material bypassed the main rift melting zone and dispersed beneath northeastern Iceland during a period of enhanced plume flux.

About the doctoral candidate:
Noemi Löw was born in 1995 in Basel, Switzerland, and grew up in a small village on the countryside. Early on, she started exploring and learning about mountains during numerous hiking trips in the Swiss Alps with her parents and her younger brother. As a teenager, she became an avid climber and mountaineer in the Swiss Alpine Youth Association and found her love for the beauty and variety of rocks and minerals in the Alps. She began her studies in Earth Sciences at ETH Zürich in 2016, and an excursion with the geochemistry group to Namibia specifically sparked her interest in geochemistry. In 2019, Noemi began her MSc degree in Geochemistry and Mineralogy at ETH Zürich with her thesis focusing on the oxygen isotope composition of rhyolites at Krafla. She began her studies as a PhD researcher with NordVulk in 2021 where she studied the geological history and origin of the Fjallgarðar Volcanic Ridge in Northeastern Iceland through the lens of geochemistry and geochronology. This research formed the basis of her PhD project which she has been working on for the last four and a half years.