Physics Forums

Physics Forums (http://www.physicsforums.com/index.php)
-   Earth (http://www.physicsforums.com/forumdisplay.php?f=84)
-   -   Plate tectonics (http://www.physicsforums.com/showthread.php?t=333935)

zankaon Sep1-09 12:48 AM

Plate tectonics
 
When did plate tectonics start? http://en.wikipedia.org/wiki/Plate_tectonics

sylas Sep1-09 01:49 AM

Re: Plate tectonics
 
Quote:

Quote by zankaon (Post 2329324)
When did plate tectonics start? http://en.wikipedia.org/wiki/Plate_tectonics

That's a bit of an open question; but it seems there are indications that it began very early; as much as 4 billion years ago. This is associated with new ideas about the "Hadean" (Hellish) era; it may not have been as diabolical as previously thought.

Here's an article from the NYT which discusses these ideas: A New Picture of the Early Earth. The relevant science article is
  • Hopkins, M. et. al. (2008) "Low heat flow inferred from >4 Gyr zircons suggests Hadean plate boundary interactions" in Nature 456, 493-496 (27 November 2008) doi:10.1038/nature07465

Cheers -- sylas

zankaon Sep9-09 01:38 AM

Re: Plate tectonics
 
Quote:

Quote by zankaon (Post 2329324)
When did plate tectonics start? http://en.wikipedia.org/wiki/Plate_tectonics

Perhaps a little at a time. Might south Pacific, with any example of colliding oceanic crust, with subducting, be suggestive? That is for 2 Archean brittle pieces colliding, with one somewhat cooler, and hence denser, might subduction occur? Might such localized process be occurring planet wide? Of course one could have ongoing mantle differentiating.

zankaon Sep12-09 03:27 AM

Re: Plate tectonics
 
Quote:

Quote by zankaon (Post 2329324)
When did plate tectonics start? http://en.wikipedia.org/wiki/Plate_tectonics

Is perhaps Mars an example wherein plate tectonics never started? Might any uniformity (i.e. no layering) to Vallis Marineris walls be consistent with no plate tectonics there? Is Mar's major volcano Olympus Mons consistent with no plate motion on Mars? Might uniqueness of 1 major volcano on Mars relate to uniqueness of Hawaiian plume? That is, might respective persistence suggest an ancient impact, and ongoing active deep conduit system? http://en.wikipedia.org/wiki/Mars

Xnn Sep12-09 08:47 PM

Re: Plate tectonics
 
Quote:

Quote by zankaon (Post 2344904)
Is perhaps Mars an example wherein plate tectonics never started?

Actually, Mars likely did have plate tectonics when it was young with a significantly molten interior. However, since Mars is so much smaller than earth, it has cooled off and there is no longer the convection necessary to move the plates.

Quote:

NASA scientists have discovered additional evidence that Mars once underwent plate tectonics, slow movement of the planet's crust, like the present-day Earth. A new map of Mars' magnetic field made by the Mars Global Surveyor spacecraft reveals a world whose history was shaped by great crustal plates being pulled apart or smashed together.
http://www.nasa.gov/centers/goddard/...gs_plates.html

zankaon Sep16-09 01:01 AM

Re: Plate tectonics
 
If one thinks of earth and Mars as heat engines, then the work they try to do is force x distance. In other words, resulting in plate motion. However the Mars heat engine (.3 earth mass) would not seem sufficient to result in plate motion. The very large size of Olympus Mons would seem consistent with no plate motion.

BigFairy Sep16-09 05:58 AM

Re: Plate tectonics
 
... it would need to be correct or.. no cigar.


All times are GMT -5. The time now is 12:26 AM.

Powered by vBulletin Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
© 2014 Physics Forums