Archives de catégorie : only geology

New insight into how magma feeds volcanic eruptions

by University of Liverpool, February 2, 2018  in ScienceDaily

Researchers have provided new insights into how molten rock (magma) moves through the Earth’s crust to feed volcanic eruptions. Using laboratory experiments involving water, jelly and laser imaging, researchers were able to demonstrate how magma magma flows through the Earth’s crust to the surface through magma-filled cracks called dykes.

Plants colonized Earth 100 million years earlier than previously thought

by Bristol University, February 19, 2019 in ScienceDaily

A new study on the timescale of plant evolution has concluded that the first plants to colonize the Earth originated around 500 million years ago — 100 million years earlier than previously thought.

For the first four billion years of Earth’s history, our planet’s continents would have been devoid of all life except microbes.

Asteroid ‘time capsules’ may help explain how life started on Earth

by Georgia Institute of Technology, February 17, 2018 in ScienceDaily

In popular culture, asteroids play the role of apocalyptic threat, get blamed for wiping out the dinosaurs — and offer an extraterrestrial source for mineral mining. But for one researcher, asteroids play an entirely different role: that of time capsules showing what molecules originally existed in our solar system. Having that information gives scientists the starting point they need to reconstruct the complex pathway that got life started on Earth.

Why the seafloor starts moving Marine scientists find possible cause of landslides off Northwest Africa

by Helmholtz Centre for Ocean Research Kiel (GEOMAR), February 13, 2018 in ScienceDaily

When the seabed loses its stability and starts to move, it often happens in much larger dimensions than landslides ashore — and at slopes with very low gradients. At the same time, discplacement of large amounts of sediment under water scan cause devastating tsunamis. However, why and when submarine landslides develop is hardly understood. Marine scientists have now published possible causes based on observations on submarine landslides off the coast of northwest Africa.

Sensitivity to lunar cycles prior to the 2007 eruption of Ruapehu volcano

by T. Girona, C. Huber, C. Caudron,  January 24, 2018 in Nature

A long-standing question in Earth Science is the extent to which seismic and volcanic activity can be regulated by tidal stresses, a repeatable and predictable external excitation induced by the Moon-Sun gravitational force. Fortnightly tides, a ~14-day amplitude modulation of the daily tidal stresses that is associated to lunar cycles, have been suggested to affect volcano dynamics. However, previous studies found contradictory results and remain mostly inconclusive. Here we study how fortnightly tides have affected Ruapehu volcano (New Zealand) from 2004 to 2016 by analysing the rolling correlation between lunar cycles and seismic amplitude recorded close to the crater. (…)

Unique underwater stalactites

by Heidelberg University, November 24, 2017 in ScienceDaily

In recent years, researchers have identified a small group of stalactites that appear to have calcified underwater instead of in a dry cave. The Hells Bells in the El Zapote cave near Puerto Morelos on the Yucatán Peninsula are just such formations. Scientists have recently investigated how these bell-shaped, meter-long formations developed, assisted by bacteria and algae.

Water cooling for the Earth’s crust

by Helmholtz Centre for Ocean Research Kiel (GEOMAR), November 21, 2017 in ScienceDaily

How deep can seawater penetrate through cracks and fissures into the seafloor? By applying a new analysis method, an international team of researchers has now discovered that the water can penetrate to depths of more than 10 kilometers below the seafloor. This result suggests a stronger cooling effect on the hot mantle.

Credit : GEOMAR

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Doggerland – The Europe That Was

by National Geography, 2017

The British Isles were once neither British nor isles

Things aren’t always what they seem on the surface. Looking at the area between mainland Europe and the eastern coast of Great Britain, you probably wouldn’t guess it had been anything other than a great expanse of ocean water. But roughly 12,000 years ago, as the last major ice age was reaching its end, the area was very different. Instead of the North Sea, the area was a series of gently sloping hills, marshland, heavily wooded valleys, and swampy lagoons: Doggerland.

The effect of giant lateral collapses on magma pathways and the location of volcanism

by F. Maccaferri et al., October 23, 2017 in NatureCommunication

Open Article

The results reveal that a lateral collapse can trigger a significant deflection of deep magma pathways in the crust, favouring the formation of a new eruptive centre within the collapse embayment. Our results have implications for the long-term evolution of intraplate volcanic ocean islands.

Global nickel anomaly links Siberian Traps eruptions and the latest Permian mass extinction

by Michael R. Rampino et al., October 2017, in Nature

Anomalous peaks of nickel abundance have been reported in Permian-Triassic boundary sections in China, Israel, Eastern Europe, Spitzbergen, and the Austrian Carnic Alps. New solution ICP-MS results of enhanced nickel from P-T boundary sections in Hungary, Japan, and Spiti, India suggest that the nickel anomalies at the end of the Permian were a worldwide phenomenon.

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Did life on Earth start due to meteorites splashing into warm little ponds?

by McMaster University, October 2, 2017 in ScinceDaily

Life on Earth began somewhere between 3.7 and 4.5 billion years ago, after meteorites splashed down and leached essential elements into warm little ponds, say scientists. Their calculations suggest that wet and dry cycles bonded basic molecular building blocks in the ponds’ nutrient-rich broth into self-replicating RNA molecules that constituted the first genetic code for life on the planet.

Lost continent of Zealandia: Scientists return from expedition to sunken land

by National Science Foundation, September 26, 2017  in ScienceDaily

Expedition co-chief scientist Rupert Sutherland of Victoria University of Wellington in New Zealand said researchers had believed that Zealandia was submerged when it separated from Australia and Antarctica about 80 million years ago.

Big geographic changes across northern Zealandia, which is about the same size as India, have implications for understanding questions such as how plants and animals dispersed and evolved in the South Pacific.