Háskóli Íslands

The defence will take place on Friday May 15th at 14:00 and will be streamed live: https://www.youtube.com/user/HIvarp/live

Ph.D. student: Anett Blischke

Dissertation title: The Jan Mayen microcontinent and Iceland Plateau: Tectono-magmatic evolution and rift propagation.

Opponents: Dr. Jenny Collier, Professor of marine geophysics, Faculty of Engineering, Department of Earth Science & Engineering, Imperial College London, United Kingdom
Dr. Sylvie Leroy, Director of research, Institut des Sciences de la Terre de Paris, Sorbonne University – CNRS, France

Advisor: Bryndís Brandsdóttir, Research Scientist at the Institute of Earth Sciences, University of Iceland

Doctoral committee: Dr. Martyn S. Stoker, visiting research fellow, Australian School of Petroleum and Energy Resources, University of Adelaide, Australia.
Dr. Prof. Carmen Gaina, Director at the Centre for Earth Evolution and Dynamics, (CEED), University of Oslo, Norway.
Dr. Freysteinn Sigmundsson, Research Scientist at the Institute of Earth Sciences, University of Iceland.

Chair of Ceremony: Dr. Magnús Tumi Guðmundsson, Professor an the Head of the Faculty of Earth Sciences, University of Iceland.

Abstract:

This study focused on the tectono-magmatic reconstruction of the Jan Mayen microcontinent (JMMC) and Iceland Plateau Rift (IPR) in context to the breakup and opening processes of the Northeast Atlantic region. The JMMC represents a narrow section of continental crust that was detached from the central East Greenland margin during the opening of the Northeast Atlantic and activation of the Iceland Plateau Rift. The IPR represents an igneous domain consisting of four distinct stages of rifting (IPR-I to IV) each corresponding to a structural domain. A tectonickinematic model was constructed by utilizing structural, volcano-stratigraphic and igneous province-mapping based on vintage and new geological, geophysical, and geochemical datasets (1960s–2017). Eleven Cenozoic seismic-stratigraphic units, define the stratigraphic framework, bound by ten unconformities and disconformities. Six of these boundaries are regional and reflect discrete tectonostratigraphic phases in the evolution of the Northeast Atlantic region.
Eocene to Miocene overlapping ridge segmentation developed during seven distinct tectonomagmatic phases, initially along the Ægir Ridge and subsequently along the northward propagating Iceland Plateau Rift, that interlinked the microcontinent with the anomalous Greenland-Iceland-Faroe ridge, prior to the subaerial formation of Iceland: (1) Pre-breakup to initial breakup phase during Paleocene (~63-56 Ma), characterized by extension, fracture and rift zone formation, followed by plateau basalt emplacement of the North Atlantic igneous province; (2) Syn-breakup during Early Eocene (∼55-53 Ma), with stepwise north-to-south development of seaward-dipping reflectors along the microcontinent´s northeastern margin and NV-SE striking fracture zone segments, prior to spreading at the Ægir ridge; (3) Full breakup along the microcontinent´s eastern margin and initiation of IPR-I during Early-Mid Eocene (~53-50 Ma); (4) Rift-transfer during Eocene (∼49-36 Ma), characterized by SSW to NNE magmatic propagation within the JMMC domain and forming of the IPR-II segment intersecting IPR-I, contemporary with cessation of spreading at the Ægir ridge; (5) Ridge transfer and tectonic rearrangement during Late Eocene to Oligocene (~36-25 Ma) was associated with the formation of segment IPR-III, the south-western Jan Mayen igneous province, and the Jan Mayen trough, separating the Jan Mayen southern ridge complex from the main Jan Mayen ridge through SW-NE rift propagation. These events were accompanied by by large scale intrusion and flood basalts, in clear proximity to the Iceland hotspot. (6) Final breakup during Late Oligocene (25-22 Ma) with emplacement of a second igneous breakup margin along the western flank of the microcontinent in conjunction with the formation of the IPR-IV and the proto-Kolbeinsey ridge, and the initiation of the proto-Iceland shelf region. (7) Full separation of the JMMC-IPR domains from the central East Greenland margin during Miocene (22-0 Ma) and spreading along the Kolbeinsey ridge. In summary, the initiation of the fanned-shaped Iceland Plateau Rift and the Jan Mayen microcontinent´s southern ridge complex was accompanied by crustal breaches and melt incursions that formed several axial rift systems and volcanic ridges. The JMMC-IPR igneous domains portray the complexity of a long-lived (Eocene to Miocene) volcanic margin within an unstable rift-transfer tectonic setting. The region represents a unique analogue Icelandtype crust; the systematic build-up of up to 10-14 km thick oceanic crust and reactivation of preexisting structural complexes by mantle anomalies; rift-transfer processes; and overlapping subaerial and sub-surface igneous activity in conjunction with microplate formation.

About the doctoral candidate:

Anett Blischke, born 1971, was raised in East Berlin, Germany. She graduated with a BSc degree in geology and palaeontology from the Technical University of Berlin in 1994. Following a year of graduate studies in regional geology, remote sensing, petrology and hydrogeology in Berlin she entered the University of Oklahoma, and graduated with a MSc degree in petroleum geology and geophysics in 1997. Anett was employed as a reservoir geologist by Phillips Petroleum in Texas and Oklahoma 1996-2001 and by Conoco-Phillips in England and Scotland, UK, 2001-2004. Anett moved to Iceland in 2004 and has since been an employee of the Akureyri Branch of the Iceland Geosurvey, specializing in geology/geophysics, geothermal exploration and marine geophysics. Anett commenced her PhD project in marine geology and geophysics, at the University of Iceland in 2015.

Anett´s PhD project is based on a compilation of a vast amount of geophysical and geological data from the Jan Mayen and Iceland Plateau regions. Her new model of the tectono-magmatic evolution of the Jan Mayen microcontinent and rift propagation within the Iceland Plateau is founded on interpretation of more than 30.000 km of seismic reflection profiles from the Iceland GeoSurvey, National Energy Authority of Iceland and cooperating institutions, collected during the last 45 years.

Anett is married to Oddur Vilhelmsson, a professor of microbiology at the University of Akureyri and they have two sons.

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