The continent fragment known as Mauritia detached about 60 million years ago while Madagascar and India drifted apart, and had been hidden under huge masses of lava. Such micro-continents in the oceans seem to occur more frequently than previously thought, says a study in the latest issue of Nature Geoscience ("A Precambrian microcontinent in the Indian Ocean," Nature Geoscience, Vol 6, doi: 10.1038/NGEO1736).
The break-up of continents is often associated with mantle plumes: These giant bubbles of hot rock rise from the deep mantle and soften the tectonic plates from below, until the plates break apart at the hotspots. This is how Eastern Gondwana broke apart about 170 million years ago. At first, one part was separated, which in turn fragmented into Madagascar, India, Australia and Antarctica, which then migrated to their present position.
Plumes currently situated underneath the islands Marion and Reunion appear to have played a role in the emergence of the Indian Ocean. If the zone of the rupture lies at the edge of a land mass (in this case Madagascar / India), fragments of this land mass may be separated off. The Seychelles are a well-known example of such a continental fragment.
A group of geoscientists from Norway, South Africa, Britain and Germany have now published a study that suggests, based on the study of lava sand grains from the beach of Mauritius, the existence of further fragments. The sand grains contain semi-precious zircons aged between 660 and 1970 million years, which is explained by the fact that the zircons were carried by the lava as it pushed through subjacent continental crust of this age.
This dating method was supplemented by a recalculation of plate tectonics, which explains exactly how and where the fragments ended up in the Indian Ocean. Dr. Bernhard Steinberger of the GFZ German Research Centre for Geosciences and Dr. Pavel Doubrovine of Oslo University calculated the hotspot trail: "On the one hand, it shows the position of the plates relative to the two hotspots at the time of the rupture, which points towards a causal relation," says
Steinberger. "On the other hand, we were able to show that the continent fragments continued to wander almost exactly over the Reunion plume, which explains how they were covered by volcanic rock." So what was previously interpreted only as the trail of the Reunion hotspot, are continental fragments which were previously not recognized as such because they were covered by the volcanic rocks of the Reunion plume. It therefore appears that such micro-continents in the ocean occur more frequently than previously thought.
Torsvik, T.H., Amundsen, H., Hartz, E.H., Corfu, F., Kusznir, N., Gaina, C., Doubrovine, P.V., Steinberger B., Ashwal, L.D. & Jamtveit, B., „A Precambrian microcontinent in the Indian Ocean", Nature Geoscience, Vol. 6, doi:10.1038/NGEO1736.
F. Ossing | Source: EurekAlert!
Further information: www.gfz-potsdam.de
More articles from Earth Sciences:
NASA's Landsat Satellite Looks for a Cloud-Free View
23.05.2013 | NASA's Goddard Space Flight Center
NASA's SDO Observes Mid-level Solar Flare
23.05.2013 | NASA's Goddard Space Flight Center
New indicator molecules visualise the activation of auto-aggressive T cells in the body as never before
Biological processes are generally based on events at the molecular and cellular level. To understand what happens in the course of infections, diseases or normal bodily functions, scientists would need to examine individual cells and their activity directly in the tissue.
The development of new microscopes and fluorescent dyes in ...
A fried breakfast food popular in Spain provided the inspiration for the development of doughnut-shaped droplets that may provide scientists with a new approach for studying fundamental issues in physics, mathematics and materials.
The doughnut-shaped droplets, a shape known as toroidal, are formed from two dissimilar liquids using a simple rotating stage and an injection needle. About a millimeter in overall size, the droplets are produced individually, their shapes maintained by a surrounding springy material made of polymers.
Droplets in this toroidal shape made ...
Frauhofer FEP will present a novel roll-to-roll manufacturing process for high-barriers and functional films for flexible displays at the SID DisplayWeek 2013 in Vancouver – the International showcase for the Display Industry.
Displays that are flexible and paper thin at the same time?! What might still seem like science fiction will be a major topic at the SID Display Week 2013 that currently takes place in Vancouver in Canada.
High manufacturing cost and a short lifetime are still a major obstacle on ...
University of Würzburg physicists have succeeded in creating a new type of laser.
Its operation principle is completely different from conventional devices, which opens up the possibility of a significantly reduced energy input requirement. The researchers report their work in the current issue of Nature.
It also emits light the waves of which are in phase with one another: the polariton laser, developed ...
Innsbruck physicists led by Rainer Blatt and Peter Zoller experimentally gained a deep insight into the nature of quantum mechanical phase transitions.
They are the first scientists that simulated the competition between two rival dynamical processes at a novel type of transition between two quantum mechanical orders. They have published the results of their work in the journal Nature Physics.
“When water boils, its molecules are released as vapor. We call this ...
23.05.2013 | Physics and Astronomy
23.05.2013 | Health and Medicine
23.05.2013 | Ecology, The Environment and Conservation
17.05.2013 | Event News
15.05.2013 | Event News
08.05.2013 | Event News