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A long - lost tectonic plate that once bear out what is today the South China Sea has been rediscover 20 million years after disappearing .
The plate is recognize only from a few rock fragments from the pot of Borneo and the ghostly remnants of its huge slab detected deep in Earth ’s mantle . It was once a quarter of the size of the Pacific Ocean . Scientists have dubbed it the " Pontus home " because at the time of its creation , it sit under an ocean known as the Pontus Ocean .
The Pontus plate, which vanished around 20 million years ago and has now been rediscovered by scientists.
" It ’s surprising to find remnants of a plate that we just did n’t bonk about at all,“Suzanna van de Lagemaat , a doctoral nominee at Utrecht University in the Netherlands , tell Live Science .
Van de Lagemaat and her colleagues were initially studying the Pacific scale under the Pacific Ocean . Tectonic platesconstantly move against one another , and the impudence in oceanic collection plate is more dull than continental plate , so oceanic shell get pushed under continental plates in a cognitive process called subduction and disappear . Sometimes , however , rocks from a lost plate get incorporated into mountain - edifice events . These remainder can signal to the location and shaping of ancient plates .
The researchers were undertake to get remnant of one of these ancient lost plates , screw as the Phoenix photographic plate , while doing fieldwork in Borneo . Scientists can take care at the magnetised property of rock’n’roll to learn when and where they organise , van de Lagemaat said ; the charismatic orbit that fence in Earth gets " locked in " to rocks when they form , and that magnetic field varies by latitude .
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But the researchers found something foreign when they analyze the rock they ’d compile in Borneo .
" This parallel of latitude did n’t agree with the latitude we scram from the other plates that we already know about , " van de Lagemaat said .
To untangle the mystery , she used computing gadget models to investigate the area ’s geology over the last 160 million years . The plate reconstruction showed a hiccough between what is now SouthChinaand Borneo — an ocean once believe to be underpinned by another ancient plate called the Izanagi plate really was n’t on that denture . Instead , the Borneo rocks fitted into that mystery gap .
The researchers learn the spot was actually occupied by a never - before - known plate , which van de Lagemaat and her team name the Pontus plate .
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The reconstruction , published Sept. 29 in the journalGondwana Research , shows that the Pontus plate formed at least 160 million old age ago but was probably far erstwhile . ( The rock samples collected in Borneo escort back 135 million age . ) It was once enormous but shrank steady over its lifetime , finally getting pushed under the Australian collection plate to the south and China to the Second Earl of Guilford , disappearing 20 million years ago .
decennary - previous inquiry from the same lab also showed a suggestion of the Pontus plate . That research looked at imaging of Earth ’s in-between layer , the mantle , where the subducted crust ends up . It showed a huge slab of crust of unidentified descent , but scientists at the fourth dimension had no way to determine where it make out from , van de Lagemaat say . Now , it ’s clear that this insolence is what ’s left of the Pontus plate .
