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Earth's Primeval Continents (Ancient / Bygone Continental Masses)

ramonmercado

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Long-lost continent found submerged deep under Indian Ocean
By Alice Klein

An ancient continent that was once sandwiched between India and Madagascar now lies scattered on the bottom of the Indian Ocean.

The first clues to the continent’s existence came when some parts of the Indian Ocean were found to have stronger gravitational fields than others, indicating thicker crusts. One theory was that chunks of land had sunk and become attached to the ocean crust below.

Mauritius was one place with a powerful gravitational pull. In 2013, Lewis Ashwal at the University of the Witwatersrand in South Africa and his colleagues proposed that the volcanic island was sitting on a piece of old, sunken continent.

Although Mauritius is only 8 million years old, some zircon crystals on the island’s beaches are almost 2 billion years old. Volcanic eruptions may have ejected the zircon from ancient rock below.

Now, Ashwal and his team have found zircon crystals in Mauritius that are up to 3 billion years old. Through detailed analyses they have reconstructed the geological history of the lost continent, which they named Mauritia. ...

https://www.newscientist.com/articl...id=SOC|NSNS|2017-Echobox#link_time=1485906278
 
Long-lost continent found submerged deep under Indian Ocean
By Alice Klein

An ancient continent that was once sandwiched between India and Madagascar now lies scattered on the bottom of the Indian Ocean.

The first clues to the continent’s existence came when some parts of the Indian Ocean were found to have stronger gravitational fields than others, indicating thicker crusts. One theory was that chunks of land had sunk and become attached to the ocean crust below.

Mauritius was one place with a powerful gravitational pull. In 2013, Lewis Ashwal at the University of the Witwatersrand in South Africa and his colleagues proposed that the volcanic island was sitting on a piece of old, sunken continent.

Although Mauritius is only 8 million years old, some zircon crystals on the island’s beaches are almost 2 billion years old. Volcanic eruptions may have ejected the zircon from ancient rock below.

Now, Ashwal and his team have found zircon crystals in Mauritius that are up to 3 billion years old. Through detailed analyses they have reconstructed the geological history of the lost continent, which they named Mauritia. ...

https://www.newscientist.com/article/2119963-long-lost-continent-found-submerged-deep-under-indian-ocean/?utm_medium=Social&utm_campaign=Echobox&utm_source=Twitter&utm_term=Autofeed&cmpid=SOC|NSNS|2017-Echobox#link_time=1485906278
So, Lemuria is back on the table?
 
There's a Lost Continent Hiding Beneath Europe

There's a lost continent hidden below southern Europe. And researchers have created the most detailed reconstruction of it yet.

The lost continent "Greater Adria" emerged about 240 million years ago, after it broke off from Gondwana, a southern supercontinent made up of Africa, Antarctica, South America, Australia and other major landmasses, as Science magazine reported.

Greater Adria was large, extending from what is now the Alps all the way to Iran, but not all of it was above the water. That means it was likely a string of islands or archipelagos, said lead author Douwe van Hinsbergen, the chair in global tectonics and paleogeography in the Department of Earth Sciences at Utrecht University in the Netherlands. It would have been a "good scuba diving region." ...

FULL STORY: https://www.livescience.com/ancient-lost-continent-beneath-europe.html
 
This is interesting, I think. The now sunken continent of Zealandia surrounding New Zealand. ...

Here's more about Zealandia ...

Zealandia , also known as the New Zealand continent or Tasmantis, is an almost entirely submerged mass of continental crust that sank after breaking away from Australia 60–85 million years ago, having separated from Antarctica between 85 and 130 million years ago. It has variously been described as a continental fragment, a microcontinent, a submerged continent, and a continent. The name and concept for Zealandia was proposed by Bruce Luyendyk in 1995. Zealandia's status as a continent is not universally accepted, but New Zealand geologist Nick Mortimer has commented that "if it wasn't for the ocean" it would have been recognized as such long ago.
FULL ARTICLE: https://en.wikipedia.org/wiki/Zealandia
 
Going even deeper ... New research suggests earth's earliest "continents" (or continent-scale rocky provinces) may survive as masses deep within the mantle.

Underground Continents May Be As Old As Earth

Underground continents deep in Earth's belly may have formed when an ancient ocean of magma solidified on the surface of the baby planet 4.5 billion years ago, according to a new study.

The finding was detailed in a fascinating story on the American Geophysical Union blog GeoSpace.

As reporter Abigail Eisenstadt explains, scientists have known about these buried blobs of hot, compressed rock since the 1970s. Earthquakes reverberate through the rest of the mantle at a steady pace, but hit serious speed bumps when they rumble through these massive hunks of stone. These peculiar patterns of seismic activity helped scientists spot the continents on the border of Earth's mantle and molten outer core, but they still don't know when or how the structures emerged. Some scientists theorize that bits of the planet's crust dipped down into the mantle, broke off and clumped together over time, Geospace reported.

Now, new analyses of volcanic rock paint a different picture: The underground continents may be as old as Earth itself, and likely survived the planet-rocking impact that first formed the Moon, the study authors reported July 31 in the journal Geochemistry, Geophysics, Geosystems.

It’s amazing that these regions have survived most of Earth’s volcanic history relatively untouched, study co-author Curtis Williams, a geologist at the University of California, Davis, told GeoSpace. ...
FULL STORY:
https://www.livescience.com/alcohol-producing-gut-bacteria-harm-liver.html

EARLIER SOURCE @ GEOSPACE BLOG:
https://blogs.agu.org/geospace/2019...ntle-untouched-for-more-than-4-billion-years/
 
The Zealandia continent (or microcontinent, if you prefer ... ) has now been mapped in detail. Illustrative maps can be accessed in the articles and website cited below.
New maps and website give fresh insights into NZ continent - 22/06/2020

21/06/2020 9:03 am

Two maps and a website released by GNS Science this week give insights into the amazing forces that shaped Aotearoa New Zealand and the mostly submerged continent that lies beneath our feet.

The maps cover the bathymetry (shape of the ocean floor) and the tectonic origins of Earth’s eighth continent – the 5 million square kilometre Te Riu-a-Māui / Zealandia on which New Zealand sits.

They can also be accessed through a new interactive website called E Tūhura - Explore Zealandia (TEZ) – http://data.gns.cri.nz/tez. TEZ is designed for exploring onland and offshore geoscience data in and around Te Riu-a-Māui / Zealandia.

“These maps are a scientific benchmark – but they’re also more than that. They’re a way of communicating our work to our colleagues, stakeholders, educators and the public,” lead author of the maps, geologist Dr Nick Mortimer says. ...

FULL STORY:
https://www.gns.cri.nz/Home/News-an...e-fresh-insights-into-NZ-continent-22-06-2020

See Also:
https://www.sciencealert.com/we-now...e-recently-discovered-8th-continent-zealandia
 
As the examples cited above illustrate, the earliest continental masses were relatively fragile and didn't last long. Newly published research based on modeling provides an explanation ...
Continents Were Weak and Prone to Destruction in Their Infancy

Monash University geologists have shed new light on the early history of the Earth through their discovery that continents were weak and prone to destruction in their infancy.

Their research, which relies on mathematical modeling, was published this month in Nature.

The Earth is our home and over its 4,500,000,000 (4.5 billion) year history has evolved to form the environment we live in and the resources on which we depend.

However, the early history of Earth, covering its first 1.5 billion years remains almost unknown and, consequently, poorly understood.

“This was the time of formation of the first continents, the emergence of land, the development of the early atmosphere, and the appearance of primordial life – all of which are the result of the dynamics of our planet’s interiors,” said lead study author ARC Future Fellow Dr. Fabio Capitanio from the Monash University School of Earth, Atmosphere and Environment.

“Reproducing the conditions of the early Earth in computer-generated numerical models, we show that the release of internal primordial heat, three to four times that of the present-day, caused large melting in the shallow mantle, which was then extruded as magma (molten rock) onto the Earth’s surface,” he said.

According to the researchers, the shallow mantle left behind by this process was dehydrated and rigid and formed the keels of the first continents.

“Our results explain that continents remained weak and prone to destruction in their infancy, ~4.5 to ~4.0 billion years ago, and then progressively differentiated and became rigid over the next billion years to form the core of our modern continents,” Dr. Capitanio said.

“The emergence of these rigid early continents resulted in their weathering and erosion, changing the composition of the atmosphere and providing nutrients to the ocean seeding the development of life.” ...

FULL STORY:
https://scitechdaily.com/continents-were-weak-and-prone-to-destruction-in-their-infancy/

PUBLISHED PAPER:
Capitanio, F.A., Nebel, O. & Cawood, P.A.
Thermochemical lithosphere differentiation and the origin of cratonic mantle.
Nature 588, 89–94 (2020).
https://doi.org/10.1038/s41586-020-2976-3
 
Another prehistoric (micro-?) continent has been tentatively identified as Balkanatolia - currently buried beneath the Balkans and Anatolia. Researchers speculate that Balkanatolia provided an intermittent land bridge or archipelago across which Asian mammals came to colonize Europe circa 40 million years ago.

MapOfBalkanatolia.jpeg
A Forgotten Continent From 40 Million Years Ago May Have Just Been Rediscovered

A low-lying continent that existed some 40 million years ago and was home to exotic fauna may have "paved the way" for Asian mammals to colonize southern Europe, new research suggests.

Wedged between Europe, Africa and Asia, this forgotten continent – which researchers have dubbed "Balkanatolia" – became a gateway between Asia and Europe when sea levels dropped and a land bridge formed, around 34 million years ago.

"When and how the first wave of Asian mammals made it to south-eastern Europe remains poorly understood," palaeogeologist Alexis Licht and colleagues write in their new study.

But the result was nothing short of dramatic. Around 34 million years ago, at the end of the Eocene epoch, huge numbers of native mammals disappeared from Western Europe as new Asian mammals emerged, in a sudden extinction event now known as the Grande Coupure.

Recent fossil findings in the Balkans, however, have upended that timeline, pointing towards a 'peculiar' bioregion that appears to have enabled Asian mammals to colonize southeastern Europe as much as 5 to 10 million years before the Grande Coupure occurred. ...

This southern pathway to Europe across Balkanatolia was perhaps more favorable for adventurous animals than traversing higher-latitude routes through Central Asia which at the time were drier, cooler, desert steppes ...

However, [the researchers] point out in their paper that the "past connectivity between individual Balkanatolian islands and the existence of this southern dispersal route remain debated", and that the story pieced together thus far "is only built on mammalian fossils and a more complete picture of past Balkanatolian biodiversity remains to be drawn". ...
FULL STORY: https://www.sciencealert.com/a-forg...-mammals-colonize-europe-34-million-years-ago


Here are the bibliographic details on the published research report. A snippet view of the report is provided at the link below.

Alexis Licht, Grégoire Métais, Pauline Coster, Deniz İbilioğlu, Faruk Ocakoğlu, Jan Westerweel, Megan Mueller, Clay Campbell, Spencer Mattingly, Melissa C. Wood, K. Christopher Beard,
Balkanatolia: The insular mammalian biogeographic province that partly paved the way to the Grande Coupure
Earth-Science Reviews, Volume 226, 2022, 103929, ISSN 0012-8252.
https://doi.org/10.1016/j.earscirev.2022.103929.

SOURCE / SNIPPET SUMMARY: https://www.sciencedirect.com/science/article/abs/pii/S0012825222000137
 
Newly published research results suggest the formation of cratons (the extra-dense crustal "cores" of continental masses) were created by massive impacts / impactor strikes during the earliest (Archaean) era of earth's history.
Continents on Ancient Earth Were Created by Giant Meteorite Impacts, Scientists Find

To date, Earth is the only planet we know of that has continents.

Exactly how they formed and evolved is unclear, but we do know – because the edges of continents thousands of miles apart match up – that, at one time long ago, Earth's landmass was concentrated in one big supercontinent.

Since that's not what the planet looks like today, something must have triggered that supercontinent to break apart. Now, we have new evidence to suggest that giant meteorite impacts played a significant role.

The smoking gun consists of crystals of the mineral zircon, excavated from a craton in Western Australia, a piece of Earth's crust that has remained stable for over a billion years.

Known as the Pilbara Craton, it is the best-preserved chunk of crust on the planet… and the zircon crystals within it contain evidence of ancient meteorite impacts before the continents broke apart.

"Studying the composition of oxygen isotopes in these zircon crystals revealed a 'top-down' process starting with the melting of rocks near the surface and progressing deeper, consistent with the geological effect of giant meteorite impacts," explained geologist Tim Johnson of Curtin University in Australia.

"Our research provides the first solid evidence that the processes that ultimately formed the continents began with giant meteorite impacts, similar to those responsible for the extinction of the dinosaurs, but which occurred billions of years earlier."

The work was conducted on 26 rock samples containing fragments of zircon, dating between 3.6 and 2.9 billion years old. ...
FULL STORY: https://www.sciencealert.com/the-continents-were-created-on-early-earth-by-giant-meteorite-impacts

See Also: https://www.livescience.com/4-billion-year-old-crust-australia
 
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