The Oldest Rock in the Earth's Surface
Updated: Apr 19, 2018
Ever wonder what is the oldest rock in the world?
And where is it located?
Many theories about the oldest formation, oldest rock and even the oldest mineral are now being proven by radiometric dating. Some may depend on the latest research, either part of the Isua Greenstone Belt, Narryer Gneiss Terrane, Nuvvuagittuq Greenstone Belt, or the Acasta Gneiss.
The Acasta Gneiss Complex of northwestern Canada contains some of the oldest dated rocks on earth. According to Stern and Bleeker of the Geological Survey of Canada, Zircon grains from the Acasta Gneiss Complex were studied based on their U-Pb isotope systematics, to have crystallized at ~4.03 Ga. Hence, considered this as one of the few old rocks known to have survived a few hundred million years of Earth's history.
The Acasta Gneiss Complex is composed of the Archaean igneous and gneissic cores of ancient mountain chains that have been exposed in a glacial peneplain.
The rock is composed mostly of quartz, plagioclase, biotite and hornblende. This is also identified as tonalite gneiss.
As of today, geologists have been discovering some other metamorphic rocks that could be as old as this one. But until then, the Acasta Gneiss is the oldest rock in the earth's surface.