Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Multiple Cosmic Impacts 790,000 Years Ago

22.02.2016

Heidelberg researchers determine age of rock glasses from various parts of the world

Approximately 790,000 years ago there were multiple cosmic impacts on earth with global consequences. Geoscientists from Heidelberg University reached this conclusion after dating so-called tektites from various parts of the world.


Tektites of different shapes from Australia. The force of the impact hurled the glass bodies thousands of kilometres. Some left the earth's atmosphere and acquired their flanged edge on re-entry

The research group under the direction of Prof. Dr. Mario Trieloff studied several of such rock glasses, which originated during impacts of asteroids or comets. The Heidelberg scientists employed a dating method based on naturally occurring isotopes that allowed them to date the tektites more accurately than ever.

Their studies show that the samples from Asia, Australia, Canada and Central America are virtually identical in age, although in some cases their chemistry differs markedly. This points to separate impacts that must have occurred around the same time. The results of their research funded by the Klaus Tschira Foundation were published in the journal “Geochimica et Cosmochimica Acta”.

The research group at the Institute of Earth Sciences and the Klaus Tschira Laboratory for Cosmochemistry uses isotope measurements to determine the age of craters caused by the impact of extraterrestrial rocks. “That's how we know when, where and how often projectiles struck the earth, and how big they were,” says Mario Trieloff. There have long been signs that a major event of this type took place on earth about a million years ago, according to Prof. Trieloff. This is evidenced by tektites, so-called rock glasses that arise during impact, whereby terrestrial material melts, is hurled up to several hundred kilometres and then hardens into glass.

“We have known about such tektites for some time from the Australasian region,” explains Dr. Winfried Schwarz, the study's primary author. These rock glasses form a strewn field that stretches from Indochina to the southernmost tip of Australia. Smaller tektites, known as microtektites, were also discovered in deep-sea drill cores off the coast of Madagascar and in the Antarctic. The rock glasses had been strewn over 10,000 kilometres, with some of them even leaving the earth's atmosphere. Using the 40Ar-39Ar dating method, which analyses the decay of the naturally occurring 40K isotope, the Heidelberg researchers succeeded in dating these tektites more accurately than ever before.

“Our data analysis indicates that there must have been a cosmic impact about 793,000 years ago, give or take 8,000 years,” explains Winfried Schwarz. The Heidelberg scientists also studied samples from Canada and Central America. The Canadian rock glasses had the same chemical composition and age as the Australasian tektites and could have covered similar “flight routes” as objects found in southern Australia or the Antarctic. Other finds must first confirm whether the recovery sites are really where the tektites originally landed or whether they for example were carried there by people, according to Dr. Schwarz.

The rock glasses from Central America are also tektites – the first specimens were found at Mayan sites of worship. In the meantime, hundreds of other finds have been made in Central America. “These tektites are clearly different in their chemical composition, and their geographical distribution also shows that they come from separate impacts,” explains Dr. Schwarz. “Surprisingly our age estimates prove that they originated 777,000 years ago with a deviation of 16,000 years. Within the error margin, this matches the age of the Australasian tektites.”

These findings led the Heidelberg researchers to conclude that there were multiple cosmic impacts approximately 790,000 years ago. In addition to the events in the Australasian and Central American regions, a smaller collision at around the same time created the Darwin crater in Tasmania. “The distribution of the tektites and the size of the strewn field indicate that the earth-striking body was at least a kilometre in size and released an impressive one million megatons of TNT energy within seconds of impact,” explains Dr. Schwarz.

According to the scientists, the consequences were dire. At the local level, there was fire and earthquakes for hundreds of kilometres surrounding the impact site; an ocean impact would have caused tsunamis hundreds of metres high. At the global level, dust and gases were ejected into the upper levels of the atmosphere, blocking sunlight and lowering surface temperatures. Biomass production was also affected, although according to the scientists it did not result in global mass extinction as in the case of the dinosaurs approximately 65 million years ago.

Original publication:
W. H. Schwarz, M. Trieloff, K. Bollinger, N. Gantert, V. A. Fernandes, H.-P. Meyer, H. Povenmire, E. K. Jessberger, M. Guglielmino, C. Koeberl: Coeval ages of Australasian, Central American and Western Canadian tektites reveal multiple impacts 790 ka ago. Geochimica et Cosmochimica Acta (2016), doi:10.1016/j.gca.2015.12.037

Contact:
Prof. Dr. Mario Trieloff
Institute of Earth Sciences
Phone +49 6221 54-6022
mario.trieloff@geow.uni-heidelberg.de

Communications and Marketing
Press Office
Phone +49 6221 54-2311
presse@rektorat.uni-heidelberg.de

Weitere Informationen:

http://www.geow.uni-heidelberg.de//forschungsgruppen/trieloff/trieloff.html

Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>