When did plate tectonics begin?

cph

When did plate tectonics begin? The early Archean was essentially shallow seas, salty water early on from rifting, shield volcanoes (no sticky silicates, since no oxygen) etc. There were no deep oceans, no mountain building, no continents, since there was no plate tectonics. One could still have uplifting oceanic like plateau (like Ontang?), but no terranes drifting together, since no plates. How long would it take a crust to cool off sufficiently so that it becomes rigid enough for plates? The earth was fully energized from mass aggregation, collisional energy, and core drop from planetesimal to proto-earth. Perhaps 1 billion years or more to cool sufficiently? Stromatolites are present at 3.5 Byrs ago, consistent with some shallow seas. If they were wide spread, might this indicate that deep oceans, high mountains, and early continent formation had not yet commenced? So was the early and middle Archean, and origin of life, largely just associated with shallow seas; very different from present plate tectonics, and resultant continents and deep oceanic environments?

DaveC426913

I would have thought the Earth as a solid enough crust in less than a billion years. I don't see why plate tectonics would not begin as soon as the crust was mostly solid.

cph

Nature 443, 811-817 (19 October 2006) | doi:10.1038/nature05191
Evolution of the continental crust

Astronuc

Well - from the abstract - "From the late Archaean to late Proterozoic eras (some 3–1 billion years ago), much of the continental crust appears to have been generated in pulses of relatively rapid growth. Reconciling the sedimentary and igneous records for crustal evolution indicates that it may take up to one billion years for new crust to dominate the sedimentary record."

So it's been evolving for the last 3 billion years or so.

The earth is rather plastic - solids flow very slowly (i.e., creep).

Ophiolite

Here is a more recent treatment that sets the initiation of plate tectonics at around 3.0 billion years ago.
http://sciencenet.cn/upload/blog/fil...4857679162.pdf

Nik_2213

Slightly OT: Have you seen how the temporary crust of lava lakes behaves ? It isn't really plate tectonics in miniature, but it suggests that a primordial 'Post-BigSplat' lava ocean would head that way as soon as any crust forms...

Of course, it would be a long time before enough depth solidifies for erosion and weathering to form sedimentary rocks...

Ophiolite

Not necessarily. The age of the Earth is 4.54 Ga. The postulated collision with Theia occured some 50 million years later. We have sedimentary zircons (from Jack Hills) dated at 4.40 Ga. So sedimentary rocks were being formed just a hundred million years after the Big Crash.

darksociety

A lot of work over the past couple of decades has been done on the Superior Province of the Canadian shield arguing for plate tectonics at least as far back as 3 Ga. This is primarily with respect to tonalite-tronjhemite-granodiorite (TGG) suites that indicate formation through metasomatized mantle wedges. The model has been further applied to explain the formation of later, Neoarchean plutons that formed from slab rollback and partial melting of thickened crust. All of that would require a process at least similar to Phanerozoic tectonics.

Prior to that time, who knows? There is evidence from ecologitic diamonds that tectonic processes were operating as far back as 3.5 Ga, but I don't think too many crustal fragments of that age have been studied for that purpose.

DaveC426913

Don' be messin' with our Canadian Shield now. Canadians believe it has been around since before the Big Bang and are very proud of it. If you go and start all ... lookin'at it an' everything ... the next thing you know it'll start falling apart like the Ross Ice Shelf and Arnie's marriage.

So just move along. It's been here forever; it'll keep bein' here forever 'f you keep your grubby mitts off it.

grandbeauch

I also think plate tectonics would start almost right after a crust formed. Kind of like a boiling pot. Movement of magma from cooler to hot drives plate tectonics. The earth had to cool for a crust to form but still stay hot enough to have convection currents.