Talk:East African Rift

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[edit] Plate boundary?

The article says that the African plate is in the process of splitting into two sub-plates. Can we therefore treat the entire rift as a plate boundary? The world has many examples of continental rifts that came very close to break-up but then became inactive, having reached beta factors of 4+ e.g. the Gulf of Suez rift and the Rockall Basin. Mikenorton (talk) 07:58, 1 April 2008 (UTC)

From what I gather in the various references, it is still regarded as one plate, although in the process of splitting. I don't know if there are any hard and fast rules about what the cutoff parameters are, but I will guess in this instance that until there is a substantial line of separation at the surface between blocks of continental crust with oceanic-type crust interposed, there is still a single plate with protoplates. Right now, we mostly see all continental crust with extension, fault blocks, grabens, etc. The southern extent of the East African Rift under the Indian Ocean is also incompletely defined, and may actually only amount to indefinite fractures on the seafloor rather than a distinct ridge or transform. A work in progress. Tmangray (talk) 21:40, 2 April 2008 (UTC)

That's my understanding also. Therefore, would it be better to reword the lead as something like

"The East African Rift is a continental rift zone that appears to be a divergent tectonic plate boundary in the making. The rift represents a narrow zone in which the African Plate is in the process of splitting into two new plates called the Nubian and Somalian subplates or protoplates. It runs from the Afar Triple Junction in the Afar Depression southward through eastern African. It is believed to run offshore of the coast of Mozambique along the Kerimba and Lacerda rifts or grabens ^[1], terminating in the Andrew Bain Fracture Zone complex, where it is believed to have its junction with the Southwest Indian Ridge. ^[2]

The East African Rift and the smaller Baikal Rift Zone in eastern Russia, are the only currently active examples of continental rift zones on Earth that appear likely to evolve into divergent plate boundaries.

The East African Rift consists of two main branches called the Eastern Rift Valley and the Western Rift Valley. These result from the actions of numerous normal (dip-slip) faults which are typical of all tectonic rift zones."

I've made a few other minor changes in there as well. What do you think? Mikenorton (talk) 08:17, 3 April 2008 (UTC)

Seems reasonable. Tmangray (talk) 15:51, 3 April 2008 (UTC)

I rev. the one paragraph because it's important to emphasize the uniqueness of the circumstances. The rift is already regarded as a divergent plate boundary, even though the plates involved are protoplates. Perhaps I should insert another qualifier like "developing" divergent plate boundary. In the case of Baikal, there's apparently already a real-life under"sea" rift under the lake, and some geologists have already declared the Amur Plate as a full-fledged plate. Tmangray (talk) 00:38, 7 April 2008 (UTC)