An embryonic rift valley in Botswana, the southwestern extension of the East African Rift System, where some of the earliest hominids have been discovered, may also hold answers to continental breakup, according to a UMR geologist who is studying how the rift has formed.
"This rift will provide us with an early snapshot of how continental rifting all begins," says Dr. Estella Atekwana, an associate professor of geology and geophysics at UMR. The study of rift basins could help scientists better understand the initial stages of continental breakup, she says.
Atekwana’s research into tectonic plate processes in Botswana’s East African Rift "will broaden our understanding of the earliest stages of passive margin development, or continental separation — a missing link in the study of early rifting processes." The sediment trapped in the basin offers clues to humanity’s past, she says.
"Almost all of the hominids that have been discovered in East Africa have come from the Rift Valley, including Olduvai Gorge, Tanzania and the Main Ethiopian Rift," says Atekwana. "It is necessary to understand rift formation mechanisms in order to unravel a large portion of the Earth’s history."
Aided by a $63,742 grant from the National Science Foundation, Atekwana is studying how tectonic plates move and develop into continental rift zones. "Here, one can examine active rifting processes in near real time without the added complication of volcanic activity and potentially related complex underplating of magmas in the crust," says Atekwana.
In an active continental rift zone, two plates are separating causing geologic activity such as volcanic eruptions, says Atekwana. But during passive margin development the plates have already separated and the volcanic eruptions have ceased, which creates the unique opportunity to study the sediment.
Such is the case at the East African Rift zone where the ground is splitting apart, revealing layers of sediment dating to more than 14 million years ago. The sediment contains not only evidence of past plants and animals, but is also an indicator of past climate.
Atekwana recently returned from a two week visit to the East African Rift zone, and also chaired a session on the structure and evolution of rift systems during the International Conference on the East African Rift System, held June 20-24 in Addis Ababa, Ethiopia.