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Studies of ‘Crater Capital’ in the Baltics show impactful history

18 Sep 2017, 05:00 UTC
Studies of ‘Crater Capital’ in the Baltics show impactful history

European Planetary Science Congress 2017 Press Notice
Embargoed for 05:00 UTC, Monday, 18 September
Studies of ‘Crater Capital’ in the Baltics show impactful history
Studies of craters in the Baltics (Estonia) are giving insights into the many impacts that have peppered the Earth over its long history. In southeastern Estonia, scientists have dated charcoal from trees destroyed in an impact to prove a common origin for two small craters, named Illumetsa. A third submarine crater located on seabed in the Gulf of Finland has been measured and dated with unprecedented precision. Results will be presented by two teams of researchers at the European Planetary Science Congress (EPSC) 2017 in Riga, Latvia, on Monday, 18th September 2017.
Illumetsa are a pair of small craters in Põlva County, Estonia, that have recently been studied by a team led by Dr Anna Losiak, a young researcher at the Polish Academy of Sciences in Warsaw. The two craters are known locally as “Hell’s Grave” and “The Devil’s Grave”, the biggest of the two being up to 80 metres in diameter at its widest point, and 12.5 metres deep. The study defined precisely the age of the two structures using a new technique.
Losiak explains: “During the impact, small pieces of charcoaled tree fragments were buried in the material expelled from the crater, called the ejecta blanket. These small pieces were found about 10 metres from the rim, at a depth of around 60 centimetres. We have established their age by carbon-14 dating. We found that both craters were formed between 7,170 and 7,000 years ago. A similar method had been used recently to date other craters in the region.”
The fact that the two Illumetsa craters are the same age strongly supports the theory that they were formed in a meteorite impact. Losiak says: “Until now, the two craters had not been firmly proven to be of extraterrestrial origin: neither remnants of the projectile nor other identification criteria had been found up to this point. The lack of signs of high temperature and pressure is not surprising because such small craters are formed by relatively low energy impacts. The lack of pieces of meteorite fragments is more unusual, but not impossible. Most small impact craters are produced by iron meteorites and you usually can find broken pieces lying around with the aid of a metal detector. Other kinds of meteorites, such as stony ones, produce impact craters only in very rare cases as they usually blow up in atmosphere – like the recent Chelabinsk meteor. However, there are exceptions and Illumetsa could have been formed by stony meteorites, not leaving any trace of the meteorite after thousands of years weathering.”
Further results were presented at EPSC about a submarine impact structure, called the Neugrund crater. The study was led by Sten Suuroja, a researcher at the Geological Survey of Estonia. Neugrund is located on the bottom of the sea at the entrance to the Gulf of Finland, to the east of the Estonian island, Osmussaar. The crater is also called the “Tomb of Odin” because Osmussaar’s name originates from the Swedish, “Odensholm”, which means the Island of Odin (a god in Germanic and Norse mythology). Distinctive structures like the central plateau and ring walls are at depths of just 2–30 metres, so are easily accessible for scuba divers.
The 20-kilometre diameter crater was discovered in 1995 through a co-operation between Estonian and Swedish geologists. The origin and development of its structural elements have been studied in numerous marine expeditions, but this new study reveals its full story.
Says Suuroja: “We found that the Neugrund structure, was formed in an asteroid impact during early Cambrian period some 535 million years ago. The body was about a kilometre in diameter and hit the sea where the depth was about 100 metres. After the impact, the crater was buried under sediments and remained covered until the Ice Age. As a result, it is probably the best preserved example of an undersea crater we have.”
Glaciation dispersed impacted rocks, called Neugrund-breccia, from newly uncovered crater rims southwards to the Estonian mainland and archipelago, up to a distance of 170 kilometres.
“There are a total of 190 structures identified around the globe as meteorite craters. Estonia could claim to be the world’s ‘Capital of craters’, being the country with the highest number per square kilometres. This record doesn’t depend on the chances of being hit: every country has roughly the same probability of being impacted by an asteroid coming from space. But regions with older rocks, that have not experienced later intensive geological activity, such as mountain formation, have a higher chance of accumulating impacts with time. Many of the craters that can be found in the Baltic region are also related to local stories and legends. Some are sightseeing venues and have become tourist attractions in recent years,” says Suuroja.
Further Information
EPSC 2017 abstracts:
http://meetingorganizer.copernicus.org/EPSC2017/EPSC2017-307.pdf
http://meetingorganizer.copernicus.org/EPSC2017/EPSC2017-934.pdf
Related results can be found in Losiak et al, “Dating a small impact crater: An age of Kaali crater (Estonia) based on charcoal emplaced within proximal ejecta”, published in Meteoritics & Planetary Science, Volume 51, Issue 4, pages 681–695, April 2016.
A map of all the confirmed impact craters on Earth can be found at: http://www.passc.net/EarthImpactDatabase/Worldmap.html
Images
Caption: An inside view of the larger Ilumetsa Crater. Credit: A. Losiak
A cross-section through the ejecta blanket of the larger Ilumetsa crater, along with close-ups of the small pieces of charcoal used to date this structure. Credit: A. Losiak
Map showing location of Estonian meteorite craters. Credit: Sten Suuroja
The seabed relief of the Neugrund crater area. Credit: Sten Suuroja
The seabed relief of the Neugrund crater area, showing the locatin of Osmussaar Island. Credit: Sten Suuroja
Science Contacts
Dr Anna Losiak
Planetary Geology Lab, Institute of Geological Sciences, Polish Academy of Sciences, Poland
anna.losiak@twarda.pan.pl
+48 660 53 56 57
Dr Sten Suuroja
Geological Survey of Estonia
s.suuroja@egk.ee
+372 53409924
Media Contacts
Anita Heward
EPSC 2017 Press Officer
+44 07756 034243
anita.heward@europlanet-eu.org
Livia Giacomini
EPSC 2017 Press Officer
livia.giacomini@europlanet-eu.org
Notes for Editors
EPSC 2017
The European Planetary Science Congress (EPSC) 2017 (www.epsc2017.eu) is taking place at the Radisson Blu Latvija in Riga, from Sunday 17 to Friday 22 September 2017. EPSC is the major European annual meeting on planetary science and in 2017 is hosted for the first time in the Baltic States. Around 800 scientists from Europe and around the world will attend the meeting and will give around 1,000 oral and poster presentations about the latest results on our own Solar System and planets orbiting other stars.
EPSC 2017 is organised by Europlanet and Copernicus Meetings. The Local Organising Committee is led by Baltics in Space, a not-for-profit organisation that is supporting 25 members centred around nine Baltic space facilities for the conference. The meeting is sponsored by Investment and Development Agency of Latvia, the Latvian Ministry of Education and Science, Latvijas Mobilais Telefons, Finnish Meteorological Institute, The Estonia-Latvia programme, The Representation of the European Commission in Latvia, the Planetary Science Institute, Latvijas Universitate and The Division for Planetary Sciences of the AAS.
Details of the Congress and a full schedule of EPSC 2017 scientific sessions and events can be found at the official website:
http://www.epsc2017.eu/
Europlanet
Since 2005, the Europlanet project has provided European’s planetary science community with a platform to exchange ideas and personnel, share research tools, data and facilities, define key science goals for the future and engage stakeholders, policy makers and European Citizens with planetary science. Europlanet is the parent organisation of the European Planetary Science Congress (EPSC), and the EPSC Executive Committee is drawn from its membership.
The Europlanet 2020 Research Infrastructure (RI) is a €9.95 million project to address key scientific and technological challenges facing modern planetary science by providing open access to state-of-the-art data, models and facilities across the European Research Area. The project was launched on 1st September 2015 and has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654208. Europlanet 2020 RI is led by the Open University, UK, and has 33 beneficiary institutions from 19 European countries.
Project website: www.europlanet-2020-ri.eu
Outreach website: www.europlanet-eu.org
Follow @europlanetmedia
Baltics in Space
The philosophy of the nonprofit organization, Baltics in Space, is to “Inventory, Identify, and Integrate” with a sprinkling of Inspiration to build a space product greater than the sum of its parts. The best resource in the space business is people. With an eye to strengthening the triple helix links (Industry, Education, Research), its planned outcomes are integrating Baltic-wide space events, compiling catalogs of skill-sets for prospective users and Baltic space project development with distributed teams and Baltic space education.
http://www.balticsinspace.eu

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