Archives par mot-clé : Geology

Sound waves reveal diamond cache deep in Earth’s interior

by Jennifer Chu, July 16 in MITNews


There may be more than a quadrillion tons of diamond hidden in the Earth’s interior, according to a new study from MIT and other universities. But the new results are unlikely to set off a diamond rush. The scientists estimate the precious minerals are buried more than 100 miles below the surface, far deeper than any drilling expedition has ever reached.

The ultradeep cache may be scattered within cratonic roots — the oldest and most immovable sections of rock that lie beneath the center of most continental tectonic plates. Shaped like inverted mountains, cratons can stretch as deep as 200 miles through the Earth’s crust and into its mantle; geologists refer to their deepest sections as “roots.”

In the new study, scientists estimate that cratonic roots may contain 1 to 2 percent diamond. Considering the total volume of cratonic roots in the Earth, the team figures that about a quadrillion (1016) tons of diamond are scattered within these ancient rocks, 90 to 150 miles below the surface.

Scientists discover Earth’s youngest banded iron formation in western China

by University of Alberta, July 11, 2018 in ScienceDaily


Discovery provides evidence of iron-rich seawater much later than previously thought.

The banded iron formation, located in western China, has been conclusively dated as Cambrian in age. Approximately 527 million years old, this formation is young by comparison to the majority of discoveries to date. The deposition of banded iron formations, which began approximately 3.8 billion years ago, had long been thought to terminate before the beginning of the Cambrian Period at 540 million years ago.

The Early Cambrian is known for the rise of animals, so the level of oxygen in seawater should have been closer to near modern levels. “This is important as the availability of oxygen has long been thought to be a handbrake on the evolution of complex life, and one that should have been alleviated by the Early Cambrian,” says Leslie Robbins, a PhD candidate in Konhauser’s lab and a co-author on the paper.

New Holocene geological subdivisions. The Anthropocene nowhere to be found.

by Javier, July 9, 2018 in WUWT


The International Commission on Stratigraphy (ICS) has announced that the proposal by the International Subcommission on Quaternary Stratigraphy (ISQS) for the subdivision of the Holocene Series/Epoch has been ratified unanimously by the International Union of Geological Sciences (IUGS).

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nb:  ‘No Christiana, the geologists do not think the Anthropocene is a concept worthy of consideration, and you should be better informed.’

Oxford University Spreads Fake News

by Donna Laframboise, July 8, 2018 in BigPicNews


SPOTLIGHT: The most reputable publishers imaginable are misinforming the public about basic geology.

BIG PICTURE: Last September, a book titled The Paris Agreement on Climate Change: Analysis and Commentary appeared. Five people are listed as editors, four of whom are lawyers. Two teach at universities. Another two are United Nations legal officers.

These people aren’t lightweights. You’d expect them to be in possession of elemental facts.

Nevertheless, not one of these editors objected to a blatant falsehood in the Foreword to this book. It’s hard to find a more distinguished publisher than Oxford University Press, but none of its editorial team caught it, either. …

Anthropocene: The Media’s Fake Geological Epoch

by Donna Laframboise, July 2018, in BigPictureNews


SPOTLIGHT: Forget reporting facts. Journalists pick sides and spread false news.

BIG PICTURE: The Breakthrough Institute is known for its sensible approach to environmental questions. The current issue of its journal includes a tour de force titled “Welcome to the Narcisscene: Returning Humans to the Center of the Cosmos.”

Author Mark Sagoff spends 5,000 words discussing a topic that should appall anyone who worries about science being hijacked by politics. The short version is that there’s an international organization “responsible for naming and dating geologic periods, eras, and epochs.” Comprised of geologists, this organization has been under immense pressure to assert that planet Earth is no longer in the geological epoch known the Holocene.

For nearly 20 years, non-geologists such as Nobel-winning atmospheric scientist Paul Crutzen, have been insisting that a new epoch should be officially declared – one that acknowledges humanity’s influence on the planet. They think it should be called the Anthropocene. (In ancient Greek, anthrop means ‘human’.)

 

Rapid 3D analysis of rockfalls in Yosemite

by Geological Society of America, June 28, 2018 in ScienceDaily


On 27 and 28 September 2017, eight large rockfalls occurred from the southeast face of El Capitan. These rockfalls resulted in one fatality and two serious injuries, and spurred a complicated rescue and temporary closure of the main road exiting Yosemite Valley. In order to manage these challenging events, the National Park Service (NPS) had a critical, immediate need for quantitative information about the sequence of rockfalls and the potential for additional activity.

Using new “structure-from-motion” photogrammetry techniques in conjunction with baseline laser-scanning data, scientists from the NPS, the U.S. Geological Survey, and the University of Lausanne, Switzerland rapidly analyzed these rockfalls. By comparing 3-dimensional (3D) models of the cliff before, during, and after the rockfalls, the researchers were able to pinpoint the exact locations, dimensions, and volumes of the rockfalls, along with the spatial and temporal pattern of their progression up the cliff.

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What caused the mass extinction of Earth’s first animals?

by Arizona State University, June 27, 2018 in ScienceDaily


Scientists have argued for decades over what may have caused this mass extinction, during what is called the “Ediacaran-Cambrian transition.” Some think that a steep decline in dissolved oxygen in the ocean was responsible. Others hypothesize that these early animals were progressively replaced by newly evolved animals.

The precise cause has remained elusive, in part because so little is known about the chemistry of Earth’s oceans that long ago.

A research team, led by scientists from Arizona State University and funded by NASA and the National Science Foundation, is helping to unravel this mystery and understand why this extinction event happened, what it can tell us about our origins, and how the world as we know it came to be. The study, published in Science Advances, was led by ASU School of Earth and Space Exploration graduate student Feifei Zhang, under the direction of faculty member Ariel Anbar and staff scientist Stephen Romaniello. (…)

Geologists detail likely site of San Andreas Fault’s next major quake

by Utah State University, June 26, 2018 in ScienceDaily


The discovery of the Durmid Ladder reveals the southern tip of the San Andreas Fault changes fairly gradually into the ladder-like Brawley Seismic zone. The structure trends northwest, extending from the well-known main trace of the San Andreas Fault along the Salton Sea’s northeastern shore, to the newly identified East Shoreline Fault Zone on the San Andreas’ opposite edge.

“We now have critical evidence about the possible nucleation site of the next major earthquake on the San Andreas Fault,” says Jänecke, professor in USU’s Department of Geology. “That possible nucleation site was thought to be a small area near Bombay Beach, California, but our work suggests there may be an additional, longer ‘fuse’ south of the Durmid Ladder within the 37-mile-long Brawley Seismic zone.” …

Stacking Up Volcanoes

by Willis Eschenbach, June 25, 2018 in WUWT


As readers of my posts know, I’ve held for many years that there are a variety of emergent phenomena that regulate the earth’s temperature. See my posts The Thermostat Hypothesisand Emergent Climate Phenomena for an overview of my hypothesis.

One of the predictions derivable from my hypothesis is that the earth should be relatively insensitive to small changes in forcing. According to my hypothesis, if the total energy entering the system changes in such a manner that the global temperatures start to drop, inter alia the system responds through changes in the time and strength of the daily emergence of the tropical cumulus field and the associated thunderstorms. This allows more sunlight to enter the system and decreases the thunderstorm-caused surface heat losses, balancing out the energy lost elsewhere and maintaining the temperature.

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Why life on Earth first got big

by University of Cambridge, June 25, 2018 in ScienceDaily


Some of the earliest complex organisms on Earth — possibly some of the earliest animals to exist — got big not to compete for food, but to spread their offspring as far as possible.

The research, led by the University of Cambridge, found that the most successful organisms living in the oceans more than half a billion years ago were the ones that were able to ‘throw’ their offspring the farthest, thereby colonising their surroundings. The results are reported in the journal Nature Ecology and Evolution.

Prior to the Ediacaran period, between 635 and 541 million years ago, life forms were microscopic in size, but during the Ediacaran, large, complex organisms first appeared, some of which — such as a type of organism known as rangeomorphs — grew as tall as two metres.

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See also here

Study provides less gloom and doom about Antarctica

by Anthony Watts, June 22, 2018 in WUWT


Antarctic ice sheet is melting, but rising bedrock below could slow it down

An international team, led by DTU Space at the Technical University of Denmark with Colorado State University, has found that the bedrock below the remote West Antarctic Ice Sheet is rising much more rapidly than previously thought, in response to ongoing ice melt.

The study, “Observed rapid bedrock uplift in the Amundsen Sea Embayment promotes ice-sheet stability,” reveals new insights on the geology of the region and its interaction with the ice sheet and is published in the journal Science. The authors noted that the findings have important implications in understanding and predicting the stability of the ice sheet and Earth’s rising sea levels.

No. The Miocene is not an example of the “last time it was as warm as it’s going to get later this century”… Argh!

by David Middleton, June 19, 2018 in WUWT


From ARS Technica, one of the most incoherent things I’ve ever read…

The shocking thing is that Howard Lee has a degree in geology.  The fact that he makes his living as an “Earth Science writer” and not as a geologist might just be relevant.

Can the Miocene tell our future?  I’ll let Bubba’s mom answer that question:

 

HOW THE EARTH BECAME A HOTHOUSE BY H2O

by Wim Röst, June 15, 2018 in WUWT


Water, H2O, determines the ‘General Background Temperature’ for the Earth, resulting in Hothouse and Ice House Climate States. During geological periods the movement of continents changes the position of
continents, oceans and seas. Because of the different configurations, a dominant warm or a dominant cold deep-water production configuration ‘sets’ average temperatures for the deep oceans. Changing vertical oceanic circulation changes surface temperatures, especially in the higher latitudes. During a Hot House State, higher temperatures in the high latitudes result in a high water-vapor concentration that prevents a rapid loss of thermal energy by the Earth.

These three processes, plate tectonics (continental drift), vertical oceanic circulation variability and variations in atmospheric water vapor concentration and distribution, caused previous Hot House and Warm House Climate States. A change in the working of those mechanisms resulted in a transition from the previous Hot House Climate State to the very cold ‘Ice House State’ that we live in now. That change was set in motion by the changing configuration of continents, oceans and seas.

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Corals use epigenetic tricks to adapt to warmer and “more acidic” water

by JoNova, June 12, 2018 inJoNovaBlog


After half a billion million years of climate change, I’m shocked, shocked I tell you, that life on Earth (and specifically corals) have so many ways to cope with the climate changing. After all, it’s natural (if you are trained by Greenpeace) to assume that corals can only survive in a world with one constant stable temperature just like they never had.

One more tool in the coral-reef-workshop

Corals don’t just have a tool-box, they have a Home Depot Warehouse. h/t to GWPF

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Volcanic activity, declining ocean oxygen triggered mass extinction of ancient organisms

by Florida State University, June 11, 2018 in ScienceDaily


Global climate change, fueled by skyrocketing levels of atmospheric carbon dioxide, is siphoning oxygen from today’s oceans at an alarming pace — so fast that scientists aren’t entirely sure how the planet will respond.

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Millions of years ago, scientists discovered, powerful volcanoes pumped Earth’s atmosphere full of carbon dioxide, draining the oceans of oxygen and driving a mass extinction of marine organisms.

Le Précambrien de l’Afrique de l’Ouest : que d’événements globaux riches d’enseignements

by Alain Préat, 31 mai 2018, Académie Royale des Sciences d’Outre- Mer


Le Précambrien représente 88% de l’histoire de la Terre âgée de 4,567 milliards d’années (Ga).

C’est au cours de cette période peu connue, peu enseignée que se sont déroulés ou mis en place des événements physico-chimiques et biologiques déterminants: différenciation des enveloppes terrestres, tectonique des plaques et premières ‘pangées’ ou supercontinents, champ magnétique, chaînes de montagnes, glaciations, anoxies des bassins, remplacement du CO2-CH4par l’oxygène atmosphérique, formation de gisements (uranium, manganèse, nickel …. et même pétrole), émergence dès 3,8 Ga des procaryotes puis des eucaryotes …

Vu l’absence de fossiles stratigraphiques, et donc de biozones, la stratigraphie du Précambrien est encore très difficile, elle  est intialement basée sur la lithostratigraphie. De grands progrès ont récemment été réalisés grâce à la chimiostratigraphie istotopique (C, O, Sr….) en plus de la radiométrie absolue.

L’exposé se consacrera aux événements sédimentaires liés au Grand Evénement de l’Oxygène il y a environ 2,5-2,1 Ga (Paléoprotérozoïque) et à ceux liés à la ‘Terre Boule de Neige’ (Snowball Earth) avec la glaciation marinoenne il y a 0,635 Ga (Néoprotérozoïque), à partir des séries de l’Afrique de l’Ouest.

 

When the dinosaurs died, so did forests — and tree-dwelling birds

By Field Museum, May 24, 2018 in ScienceDaily (CurrentBiology)


Sixty-six million years ago, the world burned. An asteroid crashed to Earth with a force one million times larger than the largest atomic bomb, causing the extinction of the dinosaurs. But dinosaurs weren’t the only ones that got hit hard — in a new study, scientists learned that the planet’s forests were decimated, leading to the extinction of tree-dwelling birds.

Remember when were told sea creatures couldn’t run from global warming? Never mind.

by Anthony Watts, may 17, 2018 in WUWT


By investigating fossils, Prof. Kießling and Dr. Carl Reddin, who is also at GeoZentrum Nordbayern, have shown that coral, molluscs, and sponges have been following their preferred cold and warm zones for half a billion years. Isotherms (geographic lines denoting the same temperature, for example 20°C) shift towards the poles or the equator as soon as the global temperature rises or decreases. Isotherms have been shifting towards the poles for several years due to global warming.

The tendency towards climate-related migration is most apparent in tropical species. This may be due to the fact that several of these species live near the thermal maximum for complex organisms of 35-45°C . Current global warming trends are driving marine animals towards the poles, provided there is a suitable habitat they can migrate to.

Earth’s orbital changes have influenced climate, life forms for at least 215 million years

by Columbia University, May 7, 2018 inPhysOrg


Scientists drilling deep into ancient rocks in the Arizona desert say they have documented a gradual shift in Earth’s orbit that repeats regularly every 405,000 years, playing a role in natural climate swings. Astrophysicists have long hypothesized that the cycle exists based on calculations of celestial mechanics, but the authors of the new research have found the first verifiable physical evidence. They showed that the cycle has been stable for hundreds of millions of years, from before the rise of dinosaurs, and is still active today. The research may have implications not only for climate studies, but our understanding of the evolution of life on Earth, and the evolution of the Solar System. It appears this week in the Proceedings of the National Academy of Sciences.

Read more here

Tiny fossils unlock clues to Earth’s climate half a billion years ago

by University of Leicester, May 9, 2018 in ScienceDaily


The research, published in Science Advances, suggests that early animals diversified within a climate similar to that in which the dinosaurs lived.

This interval in time is known for the ‘Cambrian explosion’, the time during which representatives of most of the major animal groups first appear in the fossil record. These include the first animals to produce shells, and it is these shelly fossils that the scientists used.

Data from the tiny fossil shells, and data from new climate model runs, show that high latitude (~65 °S) sea temperatures were in excess of 20 °C. This seems very hot, but it is similar to more recent, better understood, greenhouse climates like that of the Late Cretaceous Period.

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West Antarctic Volcano and Fault Belt Part of ‘Pacific Ring of Fire’

by J.E. Kamis, May 7, 2018 in ClimateChangeDispatch


The inclusion of the here-termed West Antarctic Volcano and Fault Belt into the Pacific Ring of Fire will raise scientific awareness concerning the idea, as per the Plate Climatology Theory, that geologically induced heat flow is the root cause of many anomalous changes in Antarctica’s ecosystems, oceans, climate, and ice masses.

Did the transition to plate tectonics cause Neoproterozoic Snowball Earth?

by R.J. Stern and N.M. Miller, December 20, 2017 in TerraNova


When Earth’s tectonic style transitioned from stagnant lid (single plate) to the modern episode of plate tectonics is important but unresolved, and all lines of evidence should be considered, including the climate record. The transition should have disturbed the oceans and atmosphere by redistributing continents, increasing explosive arc volcanism, stimulating mantle plumes and disrupting climate equilibrium established by the previous balance of silicate‐weathering greenhouse gas feedbacks. Formation of subduction zones would redistribute mass sufficiently to cause true polar wander if the subducted slabs were added in the upper mantle at intermediate to high latitudes. The Neoproterozoic Snowball Earth climate crisis may reflect this transition. The transition to plate tectonics is compatible with nearly all proposed geodynamic and oceanographic triggers for Neoproterozoic Snowball Earth events, and could also have contributed to biological triggers. Only extraterrestrial triggers cannot be reconciled with the hypothesis that the Neoproterozoic climate crisis was caused by a prolonged (200–250 m.y.) transition to plate tectonics.

How Oman’s Rocks Could Help Save the Planet

by Henri Fountain, April 26, 2018 in TheNewYorkTimes


IBRA, Oman — In the arid vastness of this corner of the Arabian Peninsula, out where goats and the occasional camel roam, rocks form the backdrop practically every way you look.

But the stark outcrops and craggy ridges are more than just scenery. Some of these rocks are hard at work, naturally reacting with carbon dioxide from the atmosphere and turning it into stone.

Veins of white carbonate minerals run through slabs of dark rock like fat marbling a steak. Carbonate surrounds pebbles and cobbles, turning ordinary gravel into natural mosaics.

Even pooled spring water that has bubbled up through the rocks reacts with CO2 to produce an ice-like crust of carbonate that, if broken, re-forms within days.

Scientists say that if this natural process, called carbon mineralization, could be harnessed, accelerated and applied inexpensively on a huge scale — admittedly some very big “ifs” — it could help fight climate change. Rocks could remove some of the billions of tons of heat-trapping carbon dioxide that humans have pumped into the air since the beginning of the Industrial Age.

And by turning that CO2 into stone (…)

Clear as mud: Desiccation cracks help reveal the shape of water on Mars

by Geological Society of America and in Geology, April 19,2018 in ScienceDaily


.pdf of the article

In early 2017 scientists announced the discovery of possible desiccation cracks in Gale Crater, which was filled by lakes 3.5 billion years ago. Now, a new study has confirmed that these features are indeed desiccation cracks, and reveals fresh details about Mars’ ancient climate.

“We are now confident that these are mudcracks,” explains lead author Nathaniel Stein, a geologist at the California Institute of Technology in Pasadena. Since desiccation mudcracks form only where wet sediment is exposed to air, their position closer to the center of the ancient lake bed rather than the edge also suggests that lake levels rose and fell dramatically over time.