Speedy India caused Himalayas - Study
The Himalayas and Tibetan plateau formed when a “supercontinent”
broke up and the Indian sub-continent smashed at high speed into
Eurasia, a study published on Thursday in the British journal Nature
says.
Until 140 million years ago, modern-day India formed part of a
supercontinent called Gondwanaland, which broke apart to form what,
today, is Africa, India, Australia, Antarctica and South America, it
says.
India moved at much higher speed than the other parts — at between 18
and 20 centimetres (seven to eight inches) per year, its German and
Indian authors believe.
By comparison, Australia and African plates moved at just four
centimetres (1.6 inches) per year or less, and also travelled much
smaller distances, while Antarctica remained almost stationary.
Zipping up to the north, India smashed into the continent of Eurasia
about 50 million years ago, and the mighty collision caused land to
crumple and rear up, creating the world’s highest mountain range.
The theory about Earth’s structure is that the planet comprises a
brittle outer crust, called the lithosphere, which lies atop the mantle,
the hot, elastic layer that is sandwiched between the crust and the
scorching iron-rich core.
The researchers, at the GeoForschungsZentrum (GFZ, Germany’s national
lab for geoscience) in Potsdam believe Gondwanaland fractured apart
because of a “plume” of intense heat that spewed from the mantle.
India may have been on top of, or near, this plume, with the result
that its lithospheric roots were literally burned away, leaving the
sub-continent rather like a plate floating on a fluid.
Using a method called the shear-wave receiver function technique to
measure the thickness of lithospheric plates, the GFZ team calculate the
Indian plate to be only about 100 kilometres (60 miles) thick.
That compares with between 180 and 300 kilometres (112 and 190 miles)
of thickness for the other parts of Gondwanaland, which suggests that
these parts kept some roots in the mantle, thus limiting their ability
to move. Shorn of its anchor, India was transformed “from a sloth to a
cheetah,” making it able to roam far and fast, said Dietmar Mueller, a
University of Sydney geoscientist, in a review of the study.
Paris,Thursday, (AFP) |