[meteorite-list] 65 Million-Year-Old Meteorite Traces Deep In The Ocean

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 18 Apr 2007 14:57:17 -0700 (PDT)
Message-ID: <200704182157.l3ILvHT26075_at_zagami.jpl.nasa.gov>

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

Meteorite Traces Deep In The Ocean
Kizilova Anna
Russia InfoCenter
April 17, 2007

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 Wed 18 Apr 2007 05:57:17 PM PDT