An international team, including researchers at the University of Liverpool, have shown that south east Iceland is underlain by continental crust.
The team found that the accepted theory, that Iceland consists of very thick oceanic crust, generated by the interaction between the ocean-ridge seafloor and a mantle plume, is incorrect.
In the report, maps of crustal thickness produced from satellite gravity data by Professor Nick Kusznir at the University’s School of Environmental Sciences, together with geochemical, plate tectonic reconstruction and mantle plume track analysis undertaken by the other team members, were used to show that south east Iceland is underlain by a fragment of continental crust separated from the Jan Mayan micro-continent.
Professor Kusznir said: “The established theory is that geological features such as Iceland are generated by the interaction of ocean-ridge seafloor spreading with the hot mantle of a mantle plume. Our results suggest that there is another critical ingredient which is the presence of fragments of continental crust.”
Crustal thickness mapping shows thick crust under south east Iceland of up to 30 km and more ‘typical’ continental crust, in comparison to much thinner crust in the surrounding ocean basins and under the rest of Iceland, University of Liverpool wrote.
The thick crust of south east Iceland extends eastwards offshore and is interpreted as being a sliver of continental crust originally part of, but now separated from, the Jan Mayan micro-continent to the north from which it has rifted during the formation of the north east Atlantic in the last 55 million years.
Professor Kusznir added: “Global crustal thickness mapping using gravity inversion suggests that tectonic features, such as those identified in Iceland, formed by the interaction of mantle plumes, sea-floor spreading and micro-continent fragments, are quite common.”
Crustal thickness mapping using the satellite gravity inversion methodology was developed by Professor Kusznir and has been used for locating the transition between continental and oceanic crust and micro-continents for the United Nations Convention on the Law of the Sea (UNCLOS) territorial claims and is used extensively by the hydrocarbon industry in deep water oil and gas exploration.