Archives par mot-clé : Geology

Diamonds show Earth still capable of ‘superhot’ surprises

by Europlanet Media Centre, September 21, 2017 in ScienceDaily

Diamonds may be ‘forever’ but some may have formed more recently than geologists thought. A study of 26 diamonds, formed under extreme melting conditions in the Earth’s mantle, found two populations, one of which has geologically ‘young’ ages. The results show that certain volcanic events on Earth may still be able to create super-heated conditions previously thought to have only existed early in the planet’s history before it cooled. The findings may have implications for diamond prospecting.

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The Correlation of Seismic Activity and Recent Global Warming

by Arthur Viterio, 2016, in  J Earth Science Climate Change

Earth’s climate is a remarkably “noisy” system, driven by scores of oscillators, feedback mechanisms, and radiative forcings. Amidst all this noise, identifying a solitary input to the system (i.e., HGFA MAG4/6 seismic activity as a proxy for geothermal heat flux) that explains 62% of the variation in the earth’s surface temperature is a significant finding.

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Half-a-billion-year-old fossils shed light animal evolution on Earth

by University of Manchester, September 11, 2017 in ScienceDaily

The international team, including palaeontologist from The University of Manchester, found a new set of trace fossils left by some of the first ever organisms capable of active movement. Trace fossils are the tracks and burrows left by living organisms, not physical remains such as bones or body parts.

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Possible hominin footprints from the late Miocene (c. 5.7 Ma) of Crete?

by Gerard D. Gierlinski et al., August 31, 2017 in Proc.Geologist’sAssoc.

We describe late Miocene tetrapod footprints (tracks) from the Trachilos locality in western Crete (Greece), which show hominin-like characteristics. They occur in an emergent horizon within an otherwise marginal marine succession of Messinian age (latest Miocene), dated to approximately 5.7 Ma (million years), just prior to the Messinian Salinity Crisis.

The onset of widespread marine red beds and the evolution of ferruginous oceans

by Haijun Song et al., August 2017, in Nature

Banded iron formations were a prevalent feature of marine sedimentation ~3.8–1.8 billion years ago and they provide key evidence for ferruginous oceans. The disappearance of banded iron formations at ~1.8 billion years ago was traditionally taken as evidence for the demise of ferruginous oceans, but recent geochemical studies show that ferruginous conditions persisted throughout the later Precambrian, and were even a feature of Phanerozoic ocean anoxic events.

Volcanic eruptions drove ancient global warming event

by Marcus Gutjah et al., August 30,  2017 in PhysOrg

A natural global warming event that took place 56 million years ago was triggered almost entirely by volcanic eruptions that occurred as Greenland separated from Europe during the opening of the North Atlantic Ocean,

The amount of carbon released during this time was vast—more than 30 times larger than all the fossil fuels burned to date and equivalent to all the current conventional and unconventional fossil fuel reserves we could feasibly ever extract. » Ridgwell said.

An unexpected finding was that enhanced organic matter burial was important in ultimately sequestering the released carbon and accelerating the recovery of the Earth’s ecosystem without massive extinctions.

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Réchauffement climatique : le CO2 atmosphérique n’a pas toujours été le coupable

by Alex Barral et al., 2017 (U. Lyon-CNRS)

La comparaison des fluctuations du CO2 atmosphérique retracées à partir de ces estimations avec des courbes des changements de température a révélé de fortes baisses du CO2 atmosphérique (200-300 ppm), couplées à de fortes hausses de la température moyenne à la surface du globe (5-8°C) à l’échelle de quelques millions d’années.