New Geological Map Of Earth’s Lost Continent ‘Zealandia’ Published
Possible Zealandia continent in earth planet
An artist's impression of how Earth's eight continent named Zealandia may
have looked like. [image: Possible Zealandia continent in earth planet]
In 2017, the discovery of a previously unknown continent off the shores of
New Zealand–appropriately named Zealandia or Te Riu-a-Māui in the Māori
language–made headlines worldwide. Covering more than 5 million
square-kilometres it is two-thirds the size of Australia. But despite its
size, it is no wonder it wasn't discovered sooner, as 95 percent of its
area is submerged beneath the southwest Pacific Ocean. Only remnants of a
large mountain-chain (the two islands of New Zealand) and some isolated
peaks, now small oceanic islands, are visible on the surface. Some
speculated if this "lost continent" was the inspiration for the myth of the
lost civilization of Atlantis. However, Zealandia vanished under the sea
long before humans existed on Earth.
For geologists, a continent is a large area of thick continental crust
composed of granite or similar igneous rocks, forming the continental base,
in combination with metamorphic rocks, formed in tectonically active areas
and sediments deposited by erosion on the land surface. Zealandia fits all
those points, but being almost inaccessible, little is known about its
geology in detail. (KR Hope you remember Indonesia islands and Lambok birds
written a few days back when techno plates jammed and rifted}
A team of geologists coming from New Zealand, New Caledonia, Australia, the
U.S., Denmark and Tasmania compiled a new geological map using a
combination of rock samples recovered from the sea and geophysical mapping
methods.
The researchers used rock samples recovered from the shores of various
islands, brought back from drilling operations in the open sea and dredged
from the seafloor north of New Zealand to map the extent of various
geological formations. They discovered large submersed sandstone formations
following the outer margins of Zealandia and deposits of basaltic rock
pebbles.
Survey ships mapping the magnetic field in the sea strait between Australia and
Antarctica discovered various magnetic anomalies. One anomaly is of great
interest to the geologists, as it suggests the existence of a large fault
zone along the south border of Zealandia. This fault is likely a "scar" in
Earth's crust, formed when Zealandia broke off from Antarctica and
Australia about 150 million years ago becoming its own landmass. During
this process, the continental crust was stretched and thinned out. The
crust of Zealandia is between 10 and 30 kilometres thick, which is thinner
than the 30 to 45 kilometres of the other continents.
The mapped sandstones are approximately 95 million years old and contain
older granite and volcanic pebbles, suggesting that rivers flowing from
volcanic highlands filled up tectonic basins when Zelandia was dry land.
The highlands were an active volcanic range between about 110 million and 128
million years, but likely already heavily eroded when the sandstone was
deposited. An analogous landscape resembling this depositional environment
could be the Basin and Range province covering much of the Western United
States and northwestern Mexico today.
The basalt pebbles, a typical rock associated with underwater volcanoes,
show that Zealandia was gradually flooded around 40 million years ago. The
whole region subsided by at least a kilometre to its present depth, maybe
in response to widespread tectonic activity along fault zones surrounding
the Pacific. (KR Hope you remember how sea below 256 meters rose to
submerge many parts of the earth around Indonasia}
KR IRS 15324
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