Jump to content

Leaderboard

Popular Content

Showing content with the highest reputation on 08/11/24 in all areas

  1. There is a recent paper that's been in the news a bit, from Thomas Gernon, a Prof. at Southampton, et al, which accounts for why there are uplifted plateaux several hundred km from the coast in a number of places, e.g. S Africa, Brazil, India. https://www.nature.com/articles/s41586-024-07717-1 It's quite technical, but as I understand it, they propose, via modelling, that after rifting to form a new ocean, an unstable vortex of convection is set up in the asthenosphere due to something called Rayleigh-Taylor instability (a thing in fluid dynamics, apparently). This vortex moves away from the mid-ocean ridge under the continent and progressively delaminates the "keel" of lithosphere at the base of the tectonic plate. I gather the rigid upper mantle which forms the lower part of the lithosphere is actually denser than the asthenosphere it sits above (it is rigid because it has cooled, which also makes it denser), so tearing (or melting?) off this "keel" actually causes the lithosphere to tend to rise, isostatically. The delaminated material, plus the heat in the ascending side of the vortex can cause a breakthrough of volcanism, creating the Kimberlite pipes that are a curious feature in some of these places. The vortex makes its way under the continent over a period of several tens of millions of years, so these features start to arise quite a long time after the ocean opening event. I don't pretend I know a great deal about this subject but I thought it was interesting. I had not realised that our understanding of the lithosphere has moved on so much, and that tectonic plates are now thought to comprise not just crust but a substantial chunk of cooling, solid mantle beneath as well. As it cools, the density increases and eventually the whole thing becomes unstable, due to "floating" on asthenosphere that is less dense than it has become - which is a driver for subduction.
    1 point
  2. I have it on good authority that a BOOBE is a British out of body experience. It's like an OOBE except that the sense of relief is greater.
    1 point
  3. Even if you didn't want to reply to my earlier comment, Please, Please, Please don't tell me you want medics to test new drugs and treatments on people the way IT firms fail to test properly on their customers. Or would you like they medics put out a half working drug, like a half working operating system ?
    1 point
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.