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It ’s one of many unique things about Earth : Unlike every other known major planet in the universe , Earth ’s surface is made up of rigid plates that shift , crash into each other and dive into the planet ’s interior .
But when did Earth ’s control surface splinter into tectonic plate ? And when did those plates start move ? It ’s an important doubt because home plate plate tectonic theory seems to fuel the evolution and complexness of life .
A depiction of Earth’s tectonic plates. While we know where the plates are now and into the distant past, we don’t know when the process first began.
Surprisingly , geologists do n’t have a right answer for when plate architectonics emerged , and estimates range from 700 million twelvemonth ago to before 4 billion year ago , when Earth was still in its infancy .
The old unambiguous evidence of advanced denture plate tectonic theory dates to the Neoproterozoic ( 1 billion to 541 million years ago),Robert Stern , a geoscientist at the University of Texas , Dallas , tell Live Science . That ’s when the geological record reveals plenteous ophiolites — bits of pelagic encrustation shoved onto Continent — and blueschists , which are metamorphous rocks that organise insubduction zones , or area where the plates clash and dive into the planet ’s inside . Subduction is a feature of home architectonics , so these widespread John Rock show with certainty that plate were ram into and slip under one another .
But many geologists intend Stern ’s view is too conservative .
Critics correspond that rocks revelatory of plate plate tectonics became far-flung for the first time 700 million to 900 million age ago . But these rocks could have live earlier and been wiped away by time , they propose .
For example , the Indian subcontinent collided with southerly Asia a simple 55 million year ago , and many of those rock have already erode off , saidMark Harrison , a prof emeritus of geoscientist at UCLA . " The Tibet - India collision is n’t over yet , " Harrison told Live Science . If the evidence of tectonics is go away even as a plate - to - plate collision is take place , what Bob Hope is there of finding these same rock from the much more remote past ?
Stern argues that there is evidence for alittle installment of subduction 1.8 billion years ago that did n’t quite take , bolstering his stand that if there had been plate plate tectonics consistently before about 800 million eld ago , it would be clearer in the rock record . ( Other scientists see this blip as grounds that collection plate plate tectonics was well underway by then . )
Many investigator put the transition to plate architectonics much earlier . There are numerous sign of some kind of geologic shift during the Archean Eon ( 4 billion to 2.5 billion years ago ) , with idea of on the button when rank from 2.5 billion to 3.8 billion year ago . For example , at least one ophiolite preserved todaydates back 2.5 billion year .
Another line of evidence is in the chemical science of the impertinence . If the incrustation is brand - novel volcanic stone , its chemistry will look much like the mantle from whence it came . If it is remelted and recycled by denture tectonics , this chemistry shifts . Aninfluential 2012 studyfound that more crust begin to be recycled around 3 billion years ago . This could mark the switch to subduction demolish and reworking crust , said study co - authorChris Hawkesworth , an emeritus professor of geosciences at the University of St. Andrews in the U.K ..
Research on zircons — minerals that outlive even when the rocks around them evaporate and reform — evoke that Earth ’s cheekiness shifted to begin with , around3.8 billion years ago . " We jump to see zircon structures that start to look more and more like what we see in subduction zones today , " bailiwick authorNadja Drabon , an Earth and planetary scientist at Harvard University , told Live Science . impertinence also became shorter - dwell around that prison term , again suggest the recycling appendage of subduction .
But does this modulation reflect honest plate plate tectonics ? Zircon researchpublished in 2023 , which enquire the charismatic field of operation conditions on Earth when the minerals shape , suggests that these grains more or less stick where they were made until 3.4 billion long time ago , suggest that landmasses were n’t on the move until that point .
It ’s potential that different aspects of shell tectonics emerged at different times , Drabon noted . Perhaps subduction started 3.8 billion age ago , but it took clip for the continent to start drifting around the globe .
— How many architectonic plates does Earth have ?
— home tectonics fired up at least 3 billion age ago , study of ancient rocks in Australia indicates
— Earth ’s home base architectonics retrace back to ' tipping degree ' 3.2 billion years ago
A newer and more controversial thought indicate that Earth developed plate tectonics in the Hadean ( 4.5 billion to 4 billion geezerhood ago ) . This idea springs from increase grounds that the new-sprung Earth was a surprisingly modern - looking position with oceans and Continent — a conclusion draw fromzircon researchand thechemistry of Earth ’s oldest surviving rock . Some studies of Earth ’s oldest zircon , which particular date to this mysterious menses of geologic account , found that theylook signally wish zirconium silicate that form in volcanic arcsover subduction zones today . And theoretical modeling prove it ’s possible forplate tectonics to exist in Hadean weather , Jun Korenaga , a professor of Earth and planetary scientific discipline at Yale University , told Live Science .
Every piece of grounds for each of these origin narrative comes with weaknesses . For instance , the vast majority of very old zircon amount from one position , the Jack Hills in Australia , and might not stand for what was happening on the rest of the planet . The oldest rocks might also be unearthly — perhaps they ’re still advert around today because they were n’t like all the other rocks on ancient Earth . And you do n’t want to get in the middle of computer modelers when they ’re arguing about assumptions of the state of the mantle 4 billion years ago .
" It ’s shocking to realise there ’s no consensus purview on when [ plate plate tectonics ] started,“Jesse Reimink , a geoscientist at The Pennsylvania State University told Live Science .
