Shrimp dating zircon
Geochemically, the older granitoids are metaluminous and exhibit characteristics of I-type granites and most likely formed in a convergent margin (arc) tectonic environment.
On the other hand, the younger granites are peraluminous and exhibit the characteristics of A-type granites; these are post-collisional granites.
Zircons from both samples show subrounded to rounded shapes and patchy CL patterns without inherited igneous cores, indicating that they are metamorphic zircons.
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The team examined samples and found zircons dating back three billion years in a piece of the island’s six-million-year-old piece of igneous volcanic rock.
Lewis Ashwal, a professor of geology at Wits University, said: “Earth is made up of two parts – continents, which are old, and oceans, which are ‘young’.“On the continents you find rocks that are over four billion years old, but you find nothing like that in the oceans, as this is where new rocks are formed.“Mauritius is an island, and there is no rock older than 9 million years old on the island.
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