Barberton Greenstone Belt

Source-This post on Barberton Greenstone Belt is based on the article “Oldest evidence of earthquakes found in strange jumble of 3.3 billion-year-old rocks from Africa” published in “Live Science” on 15th March 2024.

Why in the News?

Recently, scientists discovered evidence of some of the earliest recorded earthquakes in the Barberton Greenstone Belt.

About Barberton Greenstone Belt

Location– It is located on the eastern boundary of the Kaapvaal Craton in South Africa.

Significance

1. It is renowned for its gold deposits and for its komatiites, an uncommon type of ultramafic volcanic rock named after the Komati River that traverses the belt.

2. The Barberton Greenstone Belt in the Eswatini–Barberton areas contains some of the oldest exposed rocks on Earth, dating back over 3.6 billion years.

3. These rocks also preserve some of the earliest evidence of life on Earth, second only to the Isua Greenstone Belt in Western Greenland.

4. The Makhonjwa Mountains constitute 40% of the Barberton belt.

Note– The Barberton Greenstone Belt’s outcrops were added to UNESCO’s World Heritage Sites list in 2008 under the name ‘Barberton Makhonjwa Mountains’.

What are ultramafic rocks?

1. About– Ultramafic (or ultrabasic) rocks are dark-colored igneous and meta-igneous rocks. Ultramafic rocks are predominantly found in orogenic belts, where mountains are formed.

2. Composition– They mostly consist of over 90% mafic minerals, with high levels of magnesium oxide (more than 18% MgO) and iron oxide (FeO). They have low silica (less than 45%) and potassium content.

3. Significance– It is believed that the Earth’s mantle is made up of ultramafic rocks.

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