Why in News?
A rock sample recovered nearly eight years ago from Champua in Odisha’s Kendujhar district contains a grain of magmatic zircon (a mineral that contains traces of radioactive isotopes) that is an estimated 4,240 million years old.
FACTS FOR PRELIMS
The significance of the Discovery
The only instance of zircon older than this discovery was the one found in Jack Hill, Western Australia, which was 4,400 million years old and is the oldest known rock sample. But the zircon in this case was from metamorphosed sedimentary rock, unlike the Singhbhum one, which was formed from magma.
Thus, the Singhbhum rock from where the zicron was recovered is the second oldest and its zircon, the oldest magmatic zircon on earth.
NOTE4STUDENTS-Indian Rock Formation
i)Archean Formation-It is the Oldest formation and developed during Azoid conditions. Generally Found in the Aravalli’s, parts of Deccan Peninsula and some parts of North East.
ii)Dharwar System-They are the first metamorphic sedimentary rocks in India formed some 2500-1800 million yrs ago.
Found in Dharwar Karnataka, Aravallis, Tamil Nadu, Chotanagpur plateau, Meghalaya, Delhi and the Himalayas.
iii)Cuddapah system-Rich in metamorphic rocks such as Sandstone, Shale , limestone, quartzite and slate.
Mainly found at cuddapah district of Andhra Pradesh, Chattisgarh, Rajasthan, Delhi, Lesser Himalayas.
iv)Vindhyan System-It comprises of Red sandstone and other building materials . Panna and Golconda diamonds are also formed. They are extensively distributed from Rajasthan to Bihar.
v)Gondwana System-It comprises of the major coal deposits of India. Found at Raniganj, Jharia, Kanpur, Bokaro, Odisha, Chattisgarh etc.
Damodar and Son Valley and Rajmahal hills in eastern India are the depositories of the Gondwana Rocks.