[meteorite-list] Boris and Natasha write about meteorite crater in ocean

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Tue, 17 Apr 2007 10:09:10 -0500
Message-ID: <keo9231lln5i5nos89b5v064ruqf06ahrk_at_4ax.com>

Article good, English not so good. Much catch Moose and Squirrel for Fearless
Leader.

http://www.russia-ic.com/education_science/science/breakthrough/450/

Meteorite Traces Deep In The Ocean


 
A theory suggests a giant meteorite falling on Earth 65 million years ago and
killing all dinosaurs. Russian scientists have found traces of this meteorite.
During a marine expedition, organized by the Institute of Marine Geology and
Geophysics (Russian Academy of Sciences) and aimed at ocean studies, the crew of
the science and research ship ?Morskoy Geofizik (Marine Geophysicist)?
discovered an astroblem ? a circular structure, which usually forms after a
celestial body falls down from the sky ? at the bottom in north-west of the
Pacific. Researchers gave found astroblem the name ?Sakhalinka?. .

The processes that take place after celestial bodies fall into the ocean are
studied very poorly, because scientists know location of very few underwater
craters on our planet, and the fact that every new astroblem causes a tide of
scientific interest and curiosity is not surprising at all. The ?Sakhalinka?
astroblem is unique, since it is located very deep at the ocean bottom. All
known underwater craters ? Chicxulub of Mexico, Mj?lnir impact structure in the
Barents Sea and Lockne of Sweden are located between 200 and 400 m, whereas
Pacific astroblem lies as deep as 6 thousand meters.


During the expedition discovered crater was investigated by means of CSP
(continuous seismic profiling), thus its exact contours and some other
parameters were detected. Crater?s diameter at 5900 m depth is 12 km, and its
depth in basement topography is 7 hundred meters. Crater?s centre has following
geographic coordinates ? 30 degrees and 15 minutes of north latitude and 170
degrees 3 minutes of east longitude.

Scientists have thought over possible conditions, which led to ?Sakhalinka?
astroblem formation, and their calculations suggest meteorite?s diameter to
reach 500 m. Statistics of meteorite falling claims that such large objects
approach our planet only once in 100 thousand years. When such a meteorite falls
into the ocean, it generates tsunamis with waves, higher than 10 m, 1 thousand
km away from the epicenter, or the impact point in other words. However, no
matter what a splash a giant celestial body makes, when it falls to the ocean,
it forms no crater, when the ocean in the point of impact is deeper than 4
thousand meters. Therefore, ?Sakhalinka? astroblem appeared at those times, when
the ocean was much shallower than it is today.


 Russian think-tank has performed a reconstruction of paleooceanologic
environment, which brought researchers to a conclusion that during the
Cretaceous period ocean level was about 2 km lower than its current level.
Sedimentary deposits, filling the astroblem, allow stating possible crater?s age
? the structure most likely formed between the Cretaceous and Paleogene. And
then scientists have suddenly remembered the hypothesis about Earth?s collision
with a giant meteorite, happened some 65 million years ago. Meteorite rounded
our planet from south-west to north-east and fell to many smaller meteorites,
thus forming a ?crater belt?, and finally fell somewhere to the ocean. Last
trace of said celestial body on Earth scientists consider to be Kara
cryptoexplosion structure. Bearing in mind movements of ocean plate in Cenozoic
era, geologists think that ?Sakhalinka? perfectly fits into the Euro-African
crater belt and appeared because of said meteorite or a part of meteoritic cloud
had fallen to the Earth. Everything indicates that dinosaurs were in fact killed
by a giant meteorite.
Received on Tue 17 Apr 2007 11:09:10 AM PDT