Research projects – University of Copenhagen

Research projects

Here you can read about the research group's projects:

Base-line Earth, the Horizon 2020 EU ETN project (under the Marie Curie International Training Network program) 

“The ETN "BASE-LiNE Earth" project will train early stage researchers (ESRs) who will extend the knowledge of the complex and long-term Phanerozoic seawater history by the determination of original proxy information preserved in reliable ancient geological archives using cutting edge technologies and experimental approaches. In order to amplify this process the ESRs will be exposed to academic and non-academic high-tech institutions linking biogeochemical research and training in biology, ecology, geochemistry as well as chemical analytics to engineering and cutting edge analytical instrumentation.

Multi- and interdisciplinary environments will expose our ESRs to highly demanded transferable skills increasing their employability when it comes to job application. "BASE-LiNE Earth" will offer societally important deliverables like time series of past trace element and isotope cycling and models about ocean material fluxes in and out of the Phanerozoic Ocean. This will be shared in publications, reports and exhibitions. Interactive lecturing material will be offered for education in general and specifically for high school teachers.

Through collaboration with high-tech companies the ETN will contribute to establish both, new approaches for the exploration of hydrocarbon reservoirs and innovative and sophisticated analytical instrumentation for trace element and isotope measurements.

The development and application of non-traditional isotope tracers to past climate change

This project centers around the development and application of a new, non-traditional tracer – chromium isotopes - to carbonates deposited during major periods of Earth’s atmospheric oxygenation. The power of the chromium isotope system lies in its capacity to monitor and unravel subtle changes in the redox states of the ancient atmosphere and hydrosphere which are potentially preserved in limestones. Combined with the traditionally used carbon and strontium isotopic systems, chromium isotopes in carbonates offer a means to resolve fluctuations of climate and establish a link to changes of chemical weathering intensities on land through time.

The project consists of an experimental part where the mechanisms and isotopic fractionations of chromium during carbonate co-precipitations are studies, and an applications part in which the tracer is used in well constrained, well-dated world-class key sedimentary profiles in Namibia, South Africa and Argentina which were deposited during major periods of atmospheric oxygenation and which are correlated glaciations in the Paleoproterozoic (Great Oxidation Event, ~2.45 Gyr ago; Lomagundi glaciations), the Late Neoproterozoic (Marinoan and Gaskiers glaciations; ~680 Gyr and 540 Gyr ago) and in the early Phanerozoic (Great Ordovician Biodiversification Event).

The project aims at establishing the link between oxygen fluctuations on Earth through time and evolutionary stage of life, particularly those events that caused major explosion and biodiversification of life forms.

Magmatic sources during the transition from subduction to crustal break-up

Extension and eventual break-up of continents and the generation of new oceanic basins are fundamental processes in plate tectonics. These tectonic events are typically associated with magmatism, both during and after break-up, and a wide range of magmatic sources can be involved, ranging from the shallow to deep continental crust, underlying sub-continental lithospheric mantle, upwelling asthenospheric mantle and even mantle plume material from the deep mantle. The dynamic and changing tectonics can potentially result in complex interplays between these magma sources during the change from extension to complete break-up.

The aim of this study is to investigate the sources of magmatism during continental break-up, and how they vary with time, by focusing on rocks from New Zealand. The New Zealand sector of Gondwana (Zealandia) underwent a major transformation from compressional, subduction-related tectonics in the Early-mid Cretaceous through to extension and finally crustal break-up and formation of the Tasman Sea in the mid-late Cretaceous. Associated continental magmatism provides an ideal opportunity to examine the causes, styles and sources of magmatism during this transition from compressional to extensional tectonics and during the break-up of a major continent.

The project focus on detailed investigation of the timing and geochemistry of these magmas to identify the roles of crustal contamination and changing mantle sources on magmas emplaced both during and preceding break-up. In addition, detailed petrographic and geochemical investigations are being carried out on samples of the subcontinental lithospheric mantle carried to the surface in alkaline intraplate magmas to assess the role this reservoir plays in magmatism during and after break-up.

Magmatic evidence for the changes in the coupling of convergent plates and the recycling of continental and oceanic crust into the deep mantle at subduction zones

Oceanic as well as considerable parts of the continental crust are returned to the mantle at subduction zones but the mechanisms are not well understood. A study of the Southern Volcanic Zone in Argentina is aimed to constrain the the interaction of the two converging lithospheric plates as reflected in the the compositions of backarc and arc magmatism in the Andes.

Changing plate convergence rates and the crustal structure at the plate interface results in variation with time between roll-back of the oceanic plate accompanied by extension in the continental plate and flatslab subduction and crustal thickening at  times of strong convergence. During the latter, the leading edge of continental plate is abraded and transported into the mantle via the subduction channel. The changing position of the subducting slab relative to the continental margin also imposes translation of the asthenospheric mantle wedge. These major plate tectonic processes can be detected in the erupted magmas which are generated both as a consequence of the addition to the mantle of subducted material and as a consequence of the asthenospheric flow. The resulting magmas range from the compositional extremes of typical arc magmas and clearcut ocean island basalts, and this variation laterally and temporally is used to model the interaction of the plates and the flux of material into the deep mantle over the last 20 million years.

Mantle plumes and mantle dynamics

Upwellings of boyant mantle sometimes rising from the core-mantle boundary is accompanied by hot spot volcanism as seen e.g. in Iceland and the Cape Verde Islands. The initiation of hot spot volcanism may be manifest in the most massive outpourings of lava on Earth, continental flood volcansim, and result in clima change.

Around 60-55 million years ago there was a large pulse of magmatism beneath Greenland that eventually culminated in the opening of the North Atlantic. This magmatism is typically considered to be the result of the impact of a mantle plume, the remnants of which are the source for modern volcanism on Iceland. Detailed geochemical and isotopic investigations of magmatic rocks generated during break-up in East Greenland and the Faroe Islands, as well as more modern volcanics on Iceland are being used to understand the mantle sources involved in magmatism and how they have changed, or remained consistent, over time.

We also study the climatic effects and unusual volcanology of cataclysmic explosive basaltic volcanism at the end of flood basalt volcanism at these continental margins. Another study focuses on the Cape Verde hot spot which records a 20 million years  time series of changing compositions of hot mantle rising from the core-mantle boundary. These studies provide important information on mantle dynamics, in particular the transfer of energy, mass and material from the Earth’s surface, into the deep mantle and then back to the surface.

Mountain building in the wake of continental collision

Questions regarding changing climate, topography, lithosphere structure, and mantle dynamics in Central Asia are related through the single most important occurrence in the history of the region: The India-Asia collision. This event is widely recognized as a punctuated switch in the paleomagnetic, faunal and sedimentary records, and the start of renewed uplift and Ca-alkaline magmatism at 55-50 Ma. Nevertheless, very little is known about the actual geodynamic evolution of the lithosphere at the time, or during the 25 million years that followed. What processes in the deep lithosphere were responsible for the extreme changes that occurred at the surface? What triggered them, and how did they interact?

This research aims to address these and other questions relating to the evolution of the lithosphere in central Asia and its role in the formation of the extensive mountain ranges and orogenic plateaus we see in the Pamir and Tibet today. Focus areas for this research are in the Tajik Pamir and the Tibetan Himalaya, where fragments of the deep crust have become erupted and exhumed to the Earth’s surface.

The research relies on a combination between micro-structural and petrological analyses, and geochronology in order to obtain detailed information about the history of the deep crust. The mineral garnet plays a central role in these analyses. For example, garnet geochronology using the Lu-Hf and Sm-Nd systems is used to investigate the early stages of lithosphere deformation, when regional thickening and heating commenced. The information obtained from the archetypal collisional mountain belt of the Pamir-Karakorum-Himalaya serves as a guide for the geodynamics of modern collisional orogens and is of crucial importance to unravelling the lithosphere-scale feedbacks that determine the fate of our continents.