by David Middleton, January 18, 2019 in WUWT
“The Anthropocene as a geological epoch is not formally recognized”… So… “The term Anthropocene has” NOT “been widely used for the current period in Earth’s geological history“. It may be frequently used by activists and scientists who are ignorant of basic geology, but geologically speaking the term “Anthropocene” does not exist in any relationship to any period, epoch, age, era or eon in Earth’s geological history.
Yes, we have no Anthropocene, we have no Anthropocene today… Sung to the tune of Yes, We Have No Bananas.
by A. Préat et al., December 2018 in GeologicaBelgica (with .pdf)
Explaining the color of rocks is still a complex problem. This question was raised long ago in the community of geologists, particularly for the pigmentation of the ‘red marbles’ of the Frasnian of Belgium at the beginning of the last century, with many unsatisfactory hypotheses. Our recent analysis of different red carbonate rocks in Europe and North Africa (Morocco) may provide an alternative explanation for the color of these rocks. For this it was necessary to bring together diverse and complementary skills involving geologists, microbiologists and chemists. We present here a synthesis of these works. It is suggested that the red pigmentation of our studied Phanerozoic carbonate rocks, encompassing a time range from Pragian to Oxfordian, may be related to the activity of iron bacteria living in microaerophilic environments. A major conclusion is that this red color is only related to particular microenvironments and has no paleogeographic or climatic significance. All red carbonates have not necessarily acquired their pigmentation through the process established in this review. Each geological series must be analyzed in the light of a possible contribution of iron bacteria and Fungi.
by Alain Préat, 21 décembre 2018 in ScienceClimatEnergie
Cet article est le résultat d’une recherche multi-disciplinaire entre géologues et biologistes. Une synthèse de cette recherche vient d’être publiée en décembre 2018 sur le site de Geologica Belgica. Un article déjà publié dans SCE peut également être consulté.
Contrairement à ce que l’on peut penser, une question simple nécessite parfois des années de recherches avec des équipes diverses et des moyens sophistiqués. La question simple concerne ici la géologie et plus particulièrement la couleur des roches sédimentaires.
by eLife, December 18, 2018 in ScienceDaily
Scientists have described a fossil plant species that suggests flowers bloomed in the Early Jurassic, more than 174 million years ago, according to new research in the open-access journal eLife.
Before now, angiosperms (flowering plants) were thought to have a history of no more than 130 million years. The discovery of the novel flower species, which the study authors named Nanjinganthus dendrostyla, throws widely accepted theories of plant evolution into question, by suggesting that they existed around 50 million years earlier. Nanjinganthus also has a variety of ‘unexpected’ characteristics according to almost all of these theories.
by Imperial College London, December 4, 2018 in ScienceDaily
Volcanoes are not fed by molten magma formed in large chambers finds a new study, overturning classic ideas about volcanic eruptions.
Instead, the study suggests that volcanoes are fed by so-called ‘mush reservoirs’ — areas of mostly solid crystals with magma in the small spaces between the crystals.
Our understanding of volcanic processes, including those leading to the largest eruptions, has been based on magma being stored in liquid-filled ‘magma’ chambers — large, underground caves full of liquid magma. However, these have never been observed.
The new study, by researchers at Imperial College London and the University of Bristol and published today in Nature, suggests the fundamental assumption of a magma chamber needs a re-think.
by Imperial College, November 27, 2018 in ScienceDaily
The levels of oxygen dramatically rose in the atmosphere around 2.4 billion years ago, but why it happened then has been debated. Some scientists think that 2.4 billion years ago is when organisms called cyanobacteria first evolved, which could perform oxygen-producing (oxygenic) photosynthesis.
Other scientist think that cyanobacteria evolved long before 2.4 billion years ago but something prevented oxygen from accumulating in the air.
Cyanobacteria perform a relatively sophisticated form of oxygenic photosynthesis — the same type of photosynthesis that all plants do today. It has therefore been suggested that simpler forms of oxygenic photosynthesis could have existed earlier, before cyanobacteria, leading to low levels of oxygen being available to life.
Now, a research team led by Imperial College London have found that oxygenic photosynthesis arose at least one billion years before cyanobacteria evolved. Their results, published in the journal Geobiology, show that oxygenic photosynthesis could have evolved very early in Earth’s 4.5-billion-year history.
See also here
by D. Fernandez-Blanco, November 20, 2018 in EGU
What do you think are the biggest challenges right now in your field?
Some of the challenges are too hard for me even to pursue them. In the climate world, we don’t know about the role of clouds. And I don’t know how to pursue this, so I don’t pursue it. Do clouds have a cooling effect, and what is the response from clouds to warming? Will they slow or accelerate the warming? We don’t know. The role of clouds is certainly a big, big question. Although I do not work on this, I think about it, but I don’t see what to do.
One of the problems I do work on is what brought us Ice Ages. How did we go through 300 My years without much ice in the northern hemisphere and then suddenly, beginning 3My years ago or so, we had 5 big Ice Ages? Why? An easy answer is that now CO2 is higher. But it’s really hard to measure, determining CO2 in the past is a big question.
Another big question for me is how does the convection in the mantle connect with deformation in the lithosphere? How do these connect to one another?
by H. Pettit, November 9, 2018 in MailOnline
Images reveal a timeline of the ancient landmasses buried beneath Antarctica
They were taken by the long-dead Gravity field and Ocean Circulation Explorer
The ESA satellite collected data on Earth’s gravitational pull
- The study revealed that West Antarctica (green) has a thinner crust than East Antarctica (blue), which has a ‘family likeness to Australia and India’
by Anthony Watts, October 24, 2018 in WUWT
18 volcanoes in the USA are classified as “very high threat”, many are in the Pacific Northwest.
Here the .pdf (USGS, 2018)
The United States has 161 young, active volcanoes within its borders. Since 1980, there have been 120 eruptions and 52 episodes of notable volcanic unrest at 44 U.S. volcanoes.
The U.S. Geological Survey systematically assesses U.S. volcanoes considered to be active or potentially active, and publishes a volcanic threat assessment that ranks the volcanoes based on 24 hazard and exposure factors. Last published in 2005, this 2018 update considers (1) field and laboratory research that adds or removes volcanoes from the list of potentially active volcanoes, and (2) updates the hazard and exposure factors used to produce a relative threat ranking of volcanoes.
by Geological Society of America, October 9, 2018 in ScienceDaily
Even long before medieval inhabitants reclaimed land and raised dykes at a large scale, humans have had a strong impact on river behavior in the Dutch delta plain. Physical geographers have demonstrated that two present Rhine branches developed stepwise in the first centuries CE, because of two combined man-induced effects.
by University of Tennessee at Knoxville, September 26, 2018 in ScienceDaily
A new study suggests that plate tectonics — a scientific theory that divides the earth into large chunks of crust that move slowly over hot viscous mantle rock — could have been active from the planet’s very beginning. The new findings defy previous beliefs that tectonic plates were developed over the course of billions of years.
The paper, published in Earth and Planetary Science Letters, has important implications in the fields of geochemistry and geophysics. For example, a better understanding of plate tectonics could help predict whether planets beyond our solar system could be hospitable to life.
“Plate tectonics set up the conditions for life,” said Nick Dygert, assistant professor of petrology and geochemistry in UT’s Department of Earth and Planetary Sciences and coauthor of the study. “The more we know about ancient plate tectonics, the better we can understand how Earth got to be the way it is now.”
by University of Plymouth, September 14, 2018 in ScienceDaily
The British mainland was formed from the collision of not two, but three ancient continental land masses, according to new research.
Scientists have for centuries believed that England, Wales and Scotland were created by the merger of Avalonia and Laurentia more than 400 million years ago.
However, geologists based at the University of Plymouth now believe that a third land mass — Armorica — was also involved in the process.
The findings are published in Nature Communications and follow an extensive study of mineral properties at exposed rock features across Devon and Cornwall …
Credit: University of Plymouth
by University of Tennessee at Knoxville, August 27, 2018 in ScienceDaily from Nature.
Through the analysis of samples, Broadley and his team tried to determine the composition of the lithosphere. They found that before the Siberian Flood Basalts took place, the Siberian lithosphere was heavily loaded with chlorine, bromine, and iodine, all chemical elements from the halogen group. However, these elements seem to have disappeared after the volcanic eruption.
“We concluded that the large reservoir of halogens that was stored in the Siberian lithosphere was sent into the earth’s atmosphere during the volcanic explosion, effectively destroying the ozone layer at the time and contributing to the mass extinction,” Broadley said.
by Durham University, Augsut23, 2018 in ScienceDaily
The timing and size of three deadly earthquakes that struck Italy in 2016 may have been pre-determined, according to new research that could improve future earthquake forecasts.
A joint British-Italian team of geologists and seismologists have shown that the clustering of the three quakes might have been caused by the arrangement of a cross-cutting network of underground faults.
The findings show that although all three earthquakes occurred on the same major fault, several smaller faults prevented a single massive earthquake from occurring instead and also acted as pathways for naturally occurring fluids that triggered later earthquakes.
by Holly C. Betts et al., August 20, 2018 in NatureEcology&Evolution
We derive a timescale of life, combining a reappraisal of the fossil material with new molecular clock analyses. We find the last universal common ancestor of cellular life to have predated the end of late heavy bombardment (>3.9 billion years ago (Ga)). The crown clades of the two primary divisions of life, Eubacteria and Archaebacteria, emerged much later (<3.4 Ga), relegating the oldest fossil evidence for life to their stem lineages. The Great Oxidation Event significantly predates the origin of modern Cyanobacteria, indicating that oxygenic photosynthesis evolved within the cyanobacterial stem lineage. Modern eukaryotes do not constitute a primary lineage of life and emerged late in Earth’s history (<1.84 Ga), falsifying the hypothesis that the Great Oxidation Event facilitated their radiation…