Bushveld Igneous Complex

About Bushveld Igneous Complex (BIC):

• It is the largest layered igneous intrusion within the Earth's crust.
• It is located in northern South Africa, exposed at the edge of the Transvaal Basin.
• It covers a pear-shaped area of over 66,000 sq.km.
• The complex varies in thickness, sometimes reaching 9 kilometres (5.6 mi) thick. 
• It is renowned for containing some of the richest ore deposits.
  • The complex contains the world's largest reserves of platinum-group metals (PGMs), i.e., platinum, palladium, osmium, iridium, rhodium, and ruthenium, along with vast quantities of iron, tin, chromium, titanium, and vanadium.
• BIC is divided into an eastern and western lobe, with a further northern extension. All three sections of the system were formed around the same time, about 2 billion years ago. 
• Formation:
  • Vast quantities of molten rock from the Earth's mantle were brought to the surface through long vertical cracks in the Earth's crust, creating the geological intrusion known as the BIC.
  • The effects of these injections of molten rock over time, combined with the crystallisation of different minerals at different temperatures, resulted in the formation of a structure rather like a layered cake consisting of distinct rock strata including three PGM-bearing layers, referred to as reefs.

Q1: What are Igneous rocks?

Igneous rocks form when magma (molten rock) cools and crystallizes, either at volcanoes on the surface of the Earth or while the melted rock is still inside the crust. All magma develops underground, in the lower crust or upper mantle, because of the intense heat there. Igneous rocks can have many different compositions, depending on the magma they cool from.

Source: Earth’s Oldest Living Organisms Discovered Trapped in 2-Billion-Year-Old Rock