* Astronomy

Unique meteorite from asteroid smash-up

Scientists have identified a completely new type of meteorite.
The 8cm space rock is said to be chemically distinct from any of the 50,000 other such objects held in collections.
Called Österplana 65, it was found in a limestone quarry in Thorsberg, Sweden, that produces floor tiles.
Dating suggests the meteorite's parent body was involved in a huge collision in the asteroid belt between Mars and Jupiter some 470 million years ago.
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Microscopic meteorites found in Scotland have unveiled major clues about a catastrophic event which dramatically altered the Earths surface nearly 500 million years ago.
The evidence shows that life at this time, which was restricted to the seas, faced the consequences of an event far out in space.
Recent studies in Sweden have revealed that a massive collision in the asteroid belt between Mars and Jupiter resulted in thousands of meteorites landing on the Earth.
Studies by experts from the University of Aberdeen have now uncovered tiny remnants of meteorites, smaller than a grain of sand, within rocks exposed along the shore near Durness, which they believe can be tied to this event.  
The find has confirmed previous scientific speculation, that this meteorite shower was so vast in size that it affected locations across the globe including Scotland.

The study, led by Professor John Parnell from the School of Geosciences at the University of Aberdeen, has also shown that the meteorites falling to Earth may have been responsible for large earthquakes and tidal waves throughout the world.
The research, which has been published in Nature Geoscience this month, has revealed that in locations from China to the Yukon and Australia to Norway, large blocks of rock tumbled down slopes from shallow to deep water.
Pieces of rock the size of a football stadium also went sliding down hillsides in Korea, Argentina and the English Lake District.
These findings will now help scientists to investigate if there is any connection between the meteorites falling and the diversification of underwater species which took place around the same period.

Source

Title: Asteroid breakup linked to the Great Ordovician Biodiversification Event
Authors: Birger Schmitz, David A. T. Harper, Bernhard Peucker-Ehrenbrink, Svend Stouge, Carl Alwmark, Anders Cronholm, Stig M. Bergström, Mario Tassinari & Wang Xiaofeng

The rise and diversification of shelled invertebrate life in the early Phanerozoic eon occurred in two major stages. During the first stage (termed as the Cambrian explosion), a large number of new phyla appeared over a short time interval approx540 Myr ago. Biodiversity at the family, genus and species level, however, remained low until the second stage marked by the Great Ordovician Biodiversification Event in the Middle Ordovician period1, 2, 3. Although this event represents the most intense phase of species radiation during the Palaeozoic era and led to irreversible changes in the biological make-up of Earth's seafloors, the causes of this event remain elusive. Here, we show that the onset of the major phase of biodiversification approx470 Myr ago coincides with the disruption in the asteroid belt of the L-chondrite parent bodythe largest documented asteroid breakup event during the past few billion years4, 5. The precise coincidence between these two events is established by bed-by-bed records of extraterrestrial chromite, osmium isotopes and invertebrate fossils in Middle Ordovician strata in Baltoscandia and China. We argue that frequent impacts on Earth of kilometre-sized asteroidssupported by abundant Middle Ordovician fossil meteorites and impact craters6accelerated the biodiversification process.

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Space rocks are blamed for a lot of rough times on Earth, from the die-off of most marine animals some 250 million years ago to the disappearance of the dinosaurs 65 million years in the past.
A new theory, however, suggests that catastrophic meteorite impacts are linked to an explosion in biodiversity about 470 million years ago, during the Ordovician Period. Within a few million years, the number of trilobite species and scores of other creatures on Earth jumped at least three to four times.


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Credit Goniagnostus

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-- Edited by Blobrana at 21:34, 2007-12-17