To study the chemical composition of the syenites.
In the southern part of the Indian ocean is the formation of “embryonic on the continent,” reports the Chronicle.info with reference to Browser.
To such conclusion the French and Australian geologists after studying the composition of rocks of the Islands of the Kerguelen archipelago, located in the Indian ocean near Antarctica.
According to the study, the granite magma, and hence continental crust can be formed not only in subduction zones but also directly in the center of the oceans. The authors suggest that this emerging new continents.
The Islands of the archipelago is, in fact, rising above the water-capped volcanoes breaking the oceanic crust of the Kerguelen plateau. Slivovitsa of these volcanoes and basalt flows formed the island.
However, along with basalts, traditional for the oceans, there is one intrusion (magmatic introduction) more acidic in composition of rocks of the granite family – syenites are found only on continents. Due to this, the introduction of the earth’s crust in the region of Kerguelen abnormally thick on the continents.
After studying the geometry and internal structure of the intrusions of syenite Intrusive complex South Rale-du-Bati on the Central island of the archipelago, the researchers found that implementation took place as well as on the continents, in several layers, each of which was gradually raised surrounding rocks.
Dating of the layers showed that the total time of formation of the syenite intrusion covers approximately 3.7 million years from 11.6 to 7.9 million years ago.
The authors formulated the hypothesis that the syenite massif of the island of Kerguelen is, in fact, “the embryo of the continent”, which, through millions of years to become a full-fledged continent. In the article they stress that for a final conclusion it is necessary to study in detail the chemical composition of the syenite, in order to understand the origin of its magma and to reconstruct the history of its evolution.
An array of South Rale-du-Bati – the only known example of the intrusions of acid composition, located in the center of the oceanic lithospheric plate.