According to a recent work in Nature by Carnegie's Richard Carlson, Bradley Peters and Mary Horan along with James Day of the Scripps Institution of Oceanography, plumes of hot magma from the volcanic hotspot formed at the Réunion Island in the Indian Ocean rise from an unusual primitive source deep beneath the Earth's surface. This event of mantle differentiation preserved in these plumes has opened gates for research in early Earth geochemical process and also explains the odd seismic signatures created by dense deep mantle zones.
The research team is using the isotope data to show that the lava from the Réunion rises from the regions of the mantle that were isolated from broader, well-blended mantle. These isolated mantle regions were formed within 10% of the Earth's history. Overtime change in the number of neutrons in an isotope to gain stability is what helped scientists in understanding age and history of the isolated mantle pockets.
The ratio of these isotopes along with modeling studies and results of lab-based mimicry proves that Réunion plumes originated from a preserved pocket of the mantle despite millions of years of mantle mixing. Large-scale melting of the Earth's earliest mantle did change the composition of the mantle pocket. The findings can also help in understanding the origins of the dense regions at the boundary of core and mantle. These regions namely ultra low velocity zones and large low shear velocity provinces reflect an unusual slow speed of seismic waves.
By: Neha Maheshwari