Archives par mot-clé : Geology

better to know...?

«The Monster That Challenged the World»

by D. Middleton, Oct 10, 2024 in WUWT

Guest “When Sci-Fi predicted paleontology” by David Middleton

Anyone else out there remember this classically awful 1957 science fiction movie?

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By James Ashworth

First published 9 October 2024

Well-preserved fossils uncovered in France have revealed new insights into one of the biggest invertebrates to ever walk on Earth.

Arthropleura was a millipede-like animal which lived more than 300 million years ago during the Carboniferous Period, with some individuals reaching more than two metres long.

The head of one of history’s biggest arthropods has been revealed in detail for the first time.

Arthropleura is an arthropod, the group containing insects, crustaceans, arachnids and their relatives. For many years, only fossils of its body survived, which saw it placed among the earliest millipedes. Now, the discovery of the first complete head has revealed a surprising twist.

While the new fossils are not from fully grown Arthropleura, some of which reached 2.6 metres long, they reveal important characteristics. Most notably, the head has some features of early centipedes, suggesting millipedes and centipedes might be more closely related than previously accepted.

[…]

Natural History Museum

While Arthropleura wasn’t a mollusk, the first thing I thought of when I read the article was The Monster That Challenged the World.

 

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climate-debate

Causality Analysis Finds Temperature Changes Have Determined CO2 Changes Since The Phanerozoic

by K. Richard, July 15, 2024 in NoTricksZone

Popular claims that CO2 changes drive temperature changes currently or throughout the distant past “are based on imagination and climate models full of assumptions.”

A comprehensive new study details a stochastic assessment determination of the sequencing of CO2 variations versus temperature variations since the 1950s, over the last 2,000 years (the Common Era), and throughout the last 541 million years.

The robust conclusion is that the causality direction – with the understanding that causes lead and effects lag – clearly shows the temperature changes lead and CO2 changes lag on yearly, decadal, and centennial/millennial scales. In other words, “the reverse causality direction [CO2]→T should be excluded.”

The claim that CO2 increases drive temperature changes is thus a “narrative” only, as the claim that “humans, through their emissions by fossil fuel burning, are responsible for the changes we see in climate” can be regarded as a “non-scientific issue.”

 

The author has had a series of peer-reviewed scientific papers published supporting this same T→CO2 conclusion (Koutsoyiannis et al., 2022, Koutsoyiannis et al., 2020, Koutsoyiannis et al., 2023, Koutsoyiannis, 2024, Koutsoyiannis, 2024) in just the last few years.

Since these papers challenge the prevailing anthropogenic global warming (AGW) narrative so acutely, Dr. Koutsoyiannis has understandably been the recipient of antagonism bordering on vitriol from AGW proponents. This includes comments from peer-reviewers. So, in an apparent effort to foster transparency, he has made the peer reviewers’ comments on this latest paper public. Here is the link to these commentaries:

Peer reviewers’ exchanges with Koutsoyiannis in “Stochastic assessment of temperature–CO2 causal relationship in climate from the Phanerozoic through modern times.”

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better to know...?

The Earth Before Hydrocarbons

by B. Stewart, Apr 26, 2024 in ClimateChangeDispatch

prehistoric earth life plants

The Earth is approximately 4.5 billion years old. During the first four billion years, there were no hydrocarbons beneath the surface: no coal, no oil, no natural gas.

All the carbon atoms on Earth are in plants, animals, or the atmosphere. Yet the oceans did not boil. The Earth was not too hot for life. If it had been we would not be here.

The first lifeforms arose early in Earth’s existence.

The earliest fossils of microbes themselves, rather than just their byproducts, preserve the remains of what scientists think are sulfur-metabolizing bacteria. The fossils also come from Australia and date to about 3.4 billion years ago. (Wacey, D., Kilburn, M. R., Saunders, M., Cliff, J., and Brasier, M. D. (2011). Microfossils of sulfur-metabolizing cells in 3.4-billion-year-old rocks of Western Australia. Nature Geoscience, 4, 698-702. http://dx.doi.org/10.1038/ngeo1238.)

Bacteria are relatively complex, suggesting that life probably began a good deal earlier than 3.5 billion years ago.

However, the lack of earlier fossil evidence makes pinpointing the time of life’s origin difficult (if not impossible). (Hypotheses about the origins of life, Khan Academy.)

Organisms evolved that employ the process of photosynthesis. This plant life continues to consume carbon dioxide (CO2) and produce oxygen.

After a billion years or so, an atmosphere resembling that of the present day began to take shape. Earth’s present atmosphere is composed as follows:

It is important to note that in the above circle graphs, nitrogen, oxygen, and argon compose 99.964% of our atmosphere. The amount of CO2 is 0.04%.

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better to know...?

The Anthropocene is not an official stratigraphic unit

by A. Préat and B. Van Vliet-Lanoë, Apr 12,2024 in SCE

Main theme: Ever since the idea of a new geological unit, the Anthropocene, waslaunched in 2000 by Paul Crutzen, an atmospheric chemist and Nobel Prize winner, the scientific community has been inflamed by the current global warming situation, and passionate debates have raged between those in favor of this new anthropogenic unit and those opposed to it. The discussion has spread well beyond the geological community, yet it is geologists, and geologists alone, who are able to formally define geological units, in this case stratigraphic units. Our article will reviewthe rules of stratigraphy and show that the introduction of the Anthropocene as a stratigraphic unit does not comply with these rules. After 15 years of debate, the ICS (International Commission on Stratigraphy) has just officially rejected the Anthropocene as a stratigraphic unit. In conclusion, the Anthropocene must be
considered as a ‘Geo-ethical’ unit and not as a ‘Geological’ unit.

Example of the GSSP stratotype from the Thanetian geological stage (Paleocene, see Figure 1). Note the golden spike (see text below). Photography : Pierre Thomas.

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energy and fields, renewable energy

New geological study proves that the green energy movement is impossible to achieve

by R.A. Bishop, Feb 17, 2023 in LifeSite.AmericanThinker

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The comprehensive study found that the current estimated metal reserves are woefully deficient in almost every category.  The table below lists base and rare earth metals requirements to build the new grid and E.V.s.  Deficits are yellow-highlighted.  For example, copper is an integral part of a high-voltage grid system, coming up short by a shocking 3.7 billion tons.  Can we dig enough open mile-deep ore pits to meet that shortfall?  Improbable.

Table 1 Below is the study’s table estimating the years to produce the required metals at the current production rates.  For example, lithium would take almost 10 millennia to achieve.  In addition, these scarce minerals must be mined, transported, and processed, relying exclusively on fossil fuels, which would create more carbon emissions and deplete hydrocarbon reserves.

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unclassified

Abrupt episode of mid-Cretaceous ocean acidification triggered by massive volcanism

by Jones et al., Jan 2023 in NatureGeoscience

Abtsract

Large-igneous-province volcanic activity during the mid-Cretaceous triggered a global-scale episode of reduced marine oxygen levels known as Oceanic Anoxic Event 2 approximately 94.5 million years ago. It has been hypothesized that this geologically rapid degassing of volcanic carbon dioxide altered seawater carbonate chemistry, affecting marine ecosystems, geochemical cycles and sedimentation. Here we report on two sites drilled by the International Ocean Discovery Program offshore of southwest Australia that exhibit clear evidence for suppressed pelagic carbonate sedimentation in the form of a stratigraphic interval barren of carbonate minerals, recording ocean acidification during the event. We then use the osmium isotopic composition of bulk sediments to directly link this protracted ~600 kyr shoaling of the marine calcite compensation depth to the onset of volcanic activity. This decrease in marine pH was prolonged by biogeochemical feedbacks in highly productive regions where elevated heterotrophic respiration added carbon dioxide to the water column. A compilation of mid-Cretaceous marine stratigraphic records reveals a contemporaneous decrease of sedimentary carbonate content at continental slope sites globally. Thus, we contend that changes in marine carbonate chemistry are a primary ecological stress and important consequence of rapid emission of carbon dioxide during many large-igneous-province eruptions in the geologic past.

climate and geology

Successive climate crises in the deep past drove the early evolution and radiation of reptiles

by T. Simoes et al., Aug 19, 2022 in ScienceAdvance

Abstract

Climate change–induced mass extinctions provide unique opportunities to explore the impacts of global environmental disturbances on organismal evolution. However, their influence on terrestrial ecosystems remains poorly understood. Here, we provide a new time tree for the early evolution of reptiles and their closest relatives to reconstruct how the Permian-Triassic climatic crises shaped their long-term evolutionary trajectory. By combining rates of phenotypic evolution, mode of selection, body size, and global temperature data, we reveal an intimate association between reptile evolutionary dynamics and climate change in the deep past. We show that the origin and phenotypic radiation of reptiles was not solely driven by ecological opportunity following the end-Permian extinction as previously thought but also the result of multiple adaptive responses to climatic shifts spanning 57 million years.
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climate and geology

The inter-glacial cycle is not a 100,000-year cycle, it is a shorter cycle with missing beats

by M.O. Jonas, 2022, WorldJ.Adv.ResReviews

Review Article
World Journal of Advanced Research and Reviews, 2022, 13(03), 388–392
Article DOI: 10.30574/wjarr.2022.13.3.0259
Publication history:
Received on 18 February 2022; revised on 20 March 2022; accepted on 22 March 2022
Abstract:
The “100,000-year problem” refers to an apparent unexplained change in the frequency of inter-glacial periods which occurred about a million years ago. Before that, inter-glacial periods seemed to occur about every 41,000 years, in line with the obliquity Milankovich cycle. But after that, they seemed to occur about every 100,000 years, in line with the orbital inclination Milankovich cycle. Examination of the data shows that there never was a 41,000-year cycle, and that there is no 100,000-year cycle, but that the most influential cycle is the approx 21,000-year precession cycle which is the major factor in the cycles of insolation at higher latitudes. Insolation at 65N is generally regarded as the most significant of these. Inspection of the data shows that every glacial termination (start of an inter-glacial period) began at a time when insolation at 65N increased from a low point in its cycle. That not every such cycle triggered a new inter-glacial period underlines the chaotic non-linear nature of Earth’s climate. Until about a million years ago, this cycle occasionally “missed a beat”, making the inter-glacial frequency average about 41,000 years. After that, the cycle started missing more “beats”, making the inter-glacial frequency average about 100,000 years. There never was an actual 41,000-year or 100,000-year inter-glacial cycle.
Keywords:
Climate; Glacial Termination; Inter-Glacial; Milankovich Cycle; Non-Linear; Precession
Full text article in PDF:
climate and geology

AR6 and The Paleocene-Eocene Thermal Maximum

by Andy May, Aug 18, 2021 in WUWT

The PETM or Paleocene-Eocene Thermal Maximum was a warm period that began between 56.3 and 55.9 Ma (million years ago). The IPCC AR6 report (actually a draft, not a final edited report), released to the public on August 9, 2021, suggests that this warm period is similar to what is happening today and they expect to happen in the future (IPCC, 2021, pp. 2-82 & 5-14). During the PETM, it was very warm and average global surface temperatures probably peaked between 25.5°C and 26°C briefly, compared to a global surface temperature average of about 14.5°C today, as shown in Figure 1.

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oday we have tens of thousands of daily temperature measurements around the world and can calculate a fairly accurate global average surface temperature. To construct a global average for the PETM we must rely on proxy temperatures, such as oxygen isotope ratios, Calcium/Magnesium ratios in fossil shells, and fossil membrane lipids that are sensitive to temperature like Tex86. Proxy temperature values are sparsely located and have a temporal resolution, 56 Ma, of thousands to hundreds of thousands of years. Thus, in terms of rate of temperature change, they are not comparable to today’s monthly global averages.

Before diving into the PETM, we will provide some geological perspective. According to Christopher Scotese, the highest global average temperature in the Phanerozoic (the age of complex shelled organisms, or the past 550 million years) was the Triassic hothouse event, following the end of the Karoo Ice Age, around 250-300 Ma. Global average surface temperatures peaked then at about 27.9°C.

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energy and fields, minerals and ores

Danes see Greenland security risk amid Arctic tensions

by L. Peter, Nov 2019 in BBCNews

Denmark has for the first time put mineral-rich Greenland top of its national security agenda, ahead of terrorism and cybercrime.

The Defence Intelligence Service (FE) linked its change in priorities to US interest in Greenland, expressed in President Donald Trump’s desire to buy the vast Arctic territory.

Greenland is part of Denmark, but has significant autonomy, including freedom to sign major business deals.

China has mining deals with Greenland.

The FE’s head Lars Findsen said Greenland was now a top security issue for Denmark because a “power game is unfolding” between the US and other global powers in the Arctic.

In August the Danish government dismissed as “absurd” President Trump’s suggestion of a US-Denmark land deal over Greenland.

Mr Trump then cancelled a state visit to Denmark and called Danish Prime Minister Mette Frederiksen “nasty”.

The US interest in Greenland goes back decades. The US has a key Cold War-era air base at Thule, used for surveillance of space using a massive radar. It is the US military’s northernmost base, there to provide early warning of a missile attack on North America.

Why the new focus on Greenland?

Greenland’s strategic importance has grown amid increased Arctic shipping and international competition for rare minerals. Arctic waters are becoming more navigable because of melting ice, linked to global warming.

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climate and geology

Hematite reconstruction of Late Triassic hydroclimate over the Colorado Plateau

by Lepre, J & Olsen P.E., Feb 21, 2021 PNAS

Significance

Hematite provides much of the color for the classic Triassic–Jurassic “red beds” of North America and elsewhere. Measuring the spectrum of visible light reflected and absorbed by the red beds, we demonstrate that the hematite concentrations faithfully track 14.5 million years of Late Triassic monsoonal rainfall over the Colorado Plateau of Arizona and use this information to assess interrelationships between environmental perturbations, climate, and the evolution of terrestrial vertebrates. The research challenges conventional ideas that the hematite has limited use for interpreting the ancient past because it is a product of natural chemical alterations that occurred long after the beds were initially deposited.

Abstract

Hematite is the most abundant surficial iron oxide on Earth resulting from near-surface processes that make it important for addressing numerous geologic problems. While red beds have proved to be excellent paleomagnetic recorders, the early diagenetic origin of hematite in these units is often questioned. Here, we validate pigmentary hematite (“pigmentite”) as a proxy indicator for the Late Triassic environment and its penecontemporaneous origin by analyzing spectrophotometric measurements of a 14.5-My–long red bed sequence in scientific drill core CPCP-PFNP13-1A of the Chinle Formation, Arizona. Pigmentite concentrations in the red beds track the evolving pattern of the Late Triassic monsoon and indicate a long-term rise in aridity beginning at ∼215 Ma followed by increased oscillatory climate change at ∼213 Ma. These monsoonal changes are attributed to the northward drift of the Colorado Plateau as part of Laurentia into the arid subtropics during a time of fluctuating CO2. Our results refine the record of the Late Triassic monsoon and indicate significant changes in rainfall proximal to the Adamanian–Revueltian biotic transition that thus may have contributed to apparent faunal and floral events at 216 to 213 Ma.

climate and geology

Scientists Discover Plate Tectonics… Again

by D. Middleton, Feb 5, 2021 in WUWT

An upwelling of rock beneath the Atlantic may drive continents apart
The Mid-Atlantic Ridge may play a more active role in plate tectonics than thought

By Maria Temming

FEBRUARY 4, 2021

An upsurge of hot rock from deep beneath the Atlantic Ocean may be driving the continents on either side apart.

The Americas are moving away from Europe and Africa by a few centimeters each year, as the tectonic plates underlying those continents drift apart. Researchers typically think tectonic plates separate as the distant edges of those plates sink down into Earth’s mantle, creating a gap (SN: 1/13/21). Material from the upper mantle then seeps up through the rift between the plates to fill in the seafloor.

But new seismic data from the Atlantic Ocean floor show that hot rock is welling up beneath a seafloor rift called the Mid-Atlantic Ridge from hundreds of kilometers deep in Earth’s mantle. This suggests that material rising up under the ridge is not just a passive response to tectonic plates sliding apart. Rather, deep rock pushing toward Earth’s surface may be driving a wedge between the plates that helps separate them, researchers report online January 27 in Nature.

A better understanding of plate tectonics — which causes earthquakes and volcanic eruptions — could help people better prepare for these natural disasters (SN: 9/3/17).

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only geology, Pangea

The role of megacontinents in the supercontinent cycle

by Wang et al. 2020 in GeolSocAmerica OPEN ACCESS.pdf

ABSTRACT
Supercontinent Pangea was preceded by the formation of Gondwana, a “megacontinent”

about half the size of Pangea. There is much debate, however, over what role the assembly of the precursor megacontinent played in the Pangean supercontinent cycle. Here we dem- onstrate that the past three cycles of supercontinent amalgamation were each preceded by ∼200 m.y. by the assembly of a megacontinent akin to Gondwana, and that the building of a megacontinent is a geodynamically important precursor to supercontinent amalgamation. The recent assembly of Eurasia is considered as a fourth megacontinent associated with future supercontinent Amasia. We use constraints from seismology of the deep mantle for Eurasia and paleogeography for Gondwana to develop a geodynamic model for megacontinent assembly and subsequent supercontinent amalgamation. As a supercontinent breaks up, a megacontinent assembles along the subduction girdle that encircled it, at a specific location where the downwelling is most intense. The megacontinent then migrates along the girdle where it collides with other continents to form a supercontinent. The geometry of this model is consistent with the kinematic transitions from Rodinia to Gondwana to Pangea.

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See also  What might Earth’s next supercontinent look like? New study provides clues

sciences-general

Rocks show Mars once felt like Iceland

by Rice University, Jan 21, 2021 in ScienceDaily

Crater study offers window on temperatures 3.5 billion years ago

Once upon a time, seasons in Gale Crater probably felt something like those in Iceland. But nobody was there to bundle up more than 3 billion years ago.

The ancient Martian crater is the focus of a study by Rice University scientists comparing data from the Curiosity rover to places on Earth where similar geologic formations have experienced weathering in different climates.

Iceland’s basaltic terrain and cool weather, with temperatures typically less than 38 degrees Fahrenheit, turned out to be the closest analog to ancient Mars. The study determined that temperature had the biggest impact on how rocks formed from sediment deposited by ancient Martian streams were weathered by climate.

The study by postdoctoral alumnus Michael Thorpe and Martian geologist Kirsten Siebach of Rice and geoscientist Joel Hurowitz of State University of New York at Stony Brook set out to answer questions about the forces that affected sands and mud in the ancient lakebed.

Data collected by Curiosity during its travels since landing on Mars in 2012 provide details about the chemical and physical states of mudstones formed in an ancient lake, but the chemistry does not directly reveal the climate conditions when the sediment eroded upstream. For that, the researchers had to look for similar rocks and soils on Earth to find a correlation between the planets.

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biology+acidification

Volcanic eruptions directly triggered ocean acidification during Early Cretaceous

by Northwestern University, Dec 21, 2020 in ScienceDaily

Around 120 million years ago, the earth experienced an extreme environmental disruption that choked oxygen from its oceans.

Known as oceanic anoxic event (OAE) 1a, the oxygen-deprived water led to a minor — but significant — mass extinction that affected the entire globe. During this age in the Early Cretaceous Period, an entire family of sea-dwelling nannoplankton virtually disappeared.

By measuring calcium and strontium isotope abundances in nannoplankton fossils, Northwestern earth scientists have concluded the eruption of the Ontong Java Plateau large igneous province (LIP) directly triggered OAE1a. Roughly the size of Alaska, the Ontong Java LIP erupted for seven million years, making it one of the largest known LIP events ever. During this time, it spewed tons of carbon dioxide (CO2) into the atmosphere, pushing Earth into a greenhouse period that acidified seawater and suffocated the oceans.

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climate and geology

In Geological Terms, Today’s Atmospheric CO2 Concentrations Are Still Uncomfortably Low

by P. Gosselin, Dec 5, 2020 in NoTricksZone

Under 180 ppm atmospheric CO2 concentration, life on earth begins to die.

The earth came very close to that point not long ago during the Ice Ages (20,000 years ago). Then the planet warmed naturally, and an increase in atmospheric CO2 to over 200 ppm followed (new study here).

The earth saw CO2 levels of close to 8000 ppm in the past, i.e. about 20 times more than today. The following chart shows the earth’s atmospheric CO2 concentrations for the past 600 million years.

Today, thanks in large part to mankind, concentrations have risen to over 400 ppm, yet historically this remains at the very low end of the scale compared to the thousands of ppm seen naturally earlier in history.

Greening planet

Today, definitely a safer level would be near 1000 ppm. Studies unanimously show plant growth at these higher levels is far enhanced. Already today we see clear evidence the planet is greening Zhu et al. (2016), in part due to the fertilizations taking place through human emissions:

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climate and geology

Editorial: Deep Carbon Science

by D. Cardace et al., Nov 12, 2020 in Front.Earth.Sci.

Editorial on the Research Topic
Deep Carbon Science

Our understanding of the slow, deep carbon cycle, key to Earth’s habitability is examined here. Because the carbon cycle links Earth’s reservoirs on nano- to mega-scales, we must integrate geological, physical, chemical, biological, and mathematical methods to understand objects and processes so small and yet so vast. Here, we profile current research in the physical chemistry of carbon in natural and model systems, processes ongoing in the deepest portions of planets, and observations of carbon utilization by the deep biosphere. The relationships between the carbon cycle and planetary habitability are undeniable, forming a conceptual anchor to all work in deep carbon science.

Carbon minerals respond to changing pressures, temperatures, and geochemical conditions. The geologic record preserves evidence of transitional periods at the submicroscopic to regional landscape scales, and demonstrates interplay between carbon-bearing phases and the biosphere. In a new review, Morrison et al. (2020) cast a retrospective look through deep time and call for emerging approaches to clarify the coevolution of the biosphere and geosphere.

Critical to transformations of Earth’s carbon inventory over time are indomitable tectonics – which influence Earth’s surface environment, weathering, metamorphism, magmatism, and volcanism. The slow, deep (endogenous) carbon cycle refines and re-distributes carbon within Earth. In fact, over the 200-million-year-long time scale, important tectonic controls on carbon cycling emerge (Wong et al., 2019). Wong et al. (2019) document the spatiotemporal evolution of fluxes inferred from plate tectonic reconstructions, and highlight CO2 fluxes from continental rift settings post-Pangea. The volcanic flux of CO2 has been successfully reconstructed by direct study of CO2 flux through lakes and adjacent soils (Hughes et al., 2019), an important and often overlooked CO2 valve linking lithosphere, atmosphere, and hydrosphere. From perspectives rooted deeper in the tectonic system, the important roles that serpentinites play in the carbon cycle are evaluated in two senses: 1) serpentinite as a carbon vector to the deep mantle (Merdith et al., 2019), and 2) serpentine mud volcanoes as sites of carbon mobilization through organic acid release (Eickenbusch et al., 2019), in a Mariana Trench case study.

Continuer la lecture de Editorial: Deep Carbon Science →

better to know...?, only geology

East African Rift System is slowly breaking away, with Madagascar splitting into pieces

by Virginia Tech, Nov 13, 2020 in ScienceDaily

The African continent is slowly separating into several large and small tectonic blocks along the diverging East African Rift System, continuing to Madagascar — the long island just off the coast of Southeast Africa — that itself will also break apart into smaller islands.

These developments will redefine Africa and the Indian Ocean. The finding comes in a new study by D. Sarah Stamps of the Department of Geosciences for the journal Geology. The breakup is a continuation of the shattering of the supercontinent Pangea some 200 million years ago.

Rest assured, though, this isn’t happening anytime soon.

“The rate of present-day break-up is millimeters per year, so it will be millions of years before new oceans start to form,” said Stamps, an assistant professor in the Virginia Tech College of Science. “The rate of extension is fastest in the north, so we’ll see new oceans forming there first.”

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climate and geology

Permian–Triassic mass extinction pulses driven by major marine carbon cycle perturbations

by Jurikova, H. et al., Oct 19, 2020 in NatureGeoscience

Abstract

The Permian/Triassic boundary approximately 251.9 million years ago marked the most severe environmental crisis identified in the geological record, which dictated the onwards course for the evolution of life. Magmatism from Siberian Traps is thought to have played an important role, but the causational trigger and its feedbacks are yet to be fully understood. Here we present a new boron-isotope-derived seawater pH record from fossil brachiopod shells deposited on the Tethys shelf that demonstrates a substantial decline in seawater pH coeval with the onset of the mass extinction in the latest Permian. Combined with carbon isotope data, our results are integrated in a geochemical model that resolves the carbon cycle dynamics as well as the ocean redox conditions and nitrogen isotope turnover. We find that the initial ocean acidification was intimately linked to a large pulse of carbon degassing from the Siberian sill intrusions. We unravel the consequences of the greenhouse effect on the marine environment, and show how elevated sea surface temperatures, export production and nutrient input driven by increased rates of chemical weathering gave rise to widespread deoxygenation and sporadic sulfide poisoning of the oceans in the earliest Triassic. Our findings enable us to assemble a consistent biogeochemical reconstruction of the mechanisms that resulted in the largest Phanerozoic mass extinction.

climate and geology

A New Mass Extinction Event Has Been Discovered, And It Triggered The Rise of Dinosaurs

by M. Benton, Sep 25, 2020 in ScienceAlert

Huge volcanic eruptions 233 million years ago pumped carbon dioxide, methane, and water vapour into the atmosphere. This series of violent explosions, on what we now know as the west coast of Canada, led to massive global warming.

Our new research has revealed that this was a planet-changing mass extinction event that killed off many of the dominant tetrapods and heralded the dawn of the dinosaurs.

The best known mass extinction happened at the end of the Cretaceous period, 66 million years ago. This is when dinosaurs, pterosaurs, marine reptiles and ammonites all died out.

This event was caused primarily by the impact of a giant asteroid that blacked out the light of the sun and caused darkness and freezing, followed by other massive perturbations of the oceans and atmosphere.

Geologists and palaeontologists agree on a roster of five such events, of which the end-Cretaceous mass extinction was the last. So our new discovery of a previously unknown mass extinction might seem unexpected.

And yet this event, termed the Carnian Pluvial Episode (CPE), seems to have killed as many species as the giant asteroid did. Ecosystems on land and sea were profoundly changed, as the planet got warmer and drier.

On land, this triggered profound changes in plants and herbivores. In turn, with the decline of the dominant plant-eating tetrapods, such as rhynchosaurs and dicynodonts, the dinosaurs were given their chance.

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only geology

Curved rock etchings reveal which way dangerous faults ruptured—and how they might again

by P. Voosen, Sep 23, 2020 in AAAS Science

Many of the world’s most dangerous earthquake faults are a silent menace: They have not ruptured in more than a century. To gauge the hazard they pose to buildings and people, geologists cannot rely on the record of recent strikes, captured by seismometers. Instead, they must figure out how the faults behaved in the past by looking for clues in the rocks themselves, including slickenlines, scour marks along the exposed rock face of a fault that can indicate how much it slipped in past earthquakes.

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Earthquakes don’t happen all at once. Rather, the slip between rocks begins at one spot on the face of the fault—the hypocenter—and travels along it, like a zipper being unzipped. As the rupture advances, the earthquake waves it generates pile up and intensify, like the siren of an approaching ambulance. Los Angeles lies at the northern terminus of the southern San Andreas fault, Ampuero notes. “If it breaks north, toward LA, that would be pretty bad.”

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only geology, sciences-general

Life on Earth may have begun in hostile hot springs

by Jack L. Lee, Sep 245, 2020 in Sciencenews

At Bumpass Hell in California’s Lassen Volcanic National Park, the ground is literally boiling, and the aroma of rotten eggs fills the air. Gas bubbles rise through puddles of mud, producing goopy popping sounds. Jets of scorching-hot steam blast from vents in the earth. The fearsome site was named for the cowboy Kendall Bumpass, who in 1865 got too close and stepped through the thin crust. Boiling, acidic water burned his leg so badly that it had to be amputated.

Some scientists contend that life on our planet arose in such seemingly inhospitable conditions. Long before creatures roamed the Earth, hot springs like Bumpass Hell may have promoted chemical reactions that linked together simple molecules in a first step toward complexity. Other scientists, however, place the starting point for Earth’s life underwater, at the deep hydrothermal vents where heated, mineral-rich water billows from cracks in the ocean floor.

As researchers study and debate where and how life on Earth first ignited, their findings offer an important bonus. Understanding the origins of life on this planet could offer hints about where to search for life elsewhere, says Natalie Batalha, an astrophysicist at the University of California, Santa Cruz. “It has very significant implications for the future of space exploration.” Chemist Wenonah Vercoutere agrees. “The rules of physics are the same throughout the whole universe,” says Vercoutere, of NASA’s Ames Research Center in Moffett Field, Calif. “So what is there to say that the rules of biology do not also carry through and are in place and active in the whole universe?”

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energy and fields, minerals and ores

A global-scale data set of mining areas

by Maus, V. Sep 8, 2020 in ScientificData OPEN ACCESS

Abstract

The area used for mineral extraction is a key indicator for understanding and mitigating the environmental impacts caused by the extractive sector. To date, worldwide data products on mineral extraction do not report the area used by mining activities. In this paper, we contribute to filling this gap by presenting a new data set of mining extents derived by visual interpretation of satellite images. We delineated mining areas within a 10 km buffer from the approximate geographical coordinates of more than six thousand active mining sites across the globe. The result is a global-scale data set consisting of 21,060 polygons that add up to 57,277 km2. The polygons cover all mining above-ground features that could be identified from the satellite images, including open cuts, tailings dams, waste rock dumps, water ponds, and processing infrastructure. The data set is available for download from https://doi.org/10.1594/PANGAEA.910894 and visualization at www.fineprint.global/viewer.

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climate and geology

SANGAY VOLCANO ERUPTS TO 40,000 FT (12.2 KM)

by Cap Allon, Sep 21, 2020 in Electroverse

Ecuador’s active Sangay Volcano exploded in dramatic fashion over the weekend, firing volcanic ash high into the atmosphere — the explosion was a number of times stronger than those previously observed during the volcano’s recent uptick.

The ‘high-level’ eruption occurred at 04:20 local time on Sunday, September 20 and generated a dense, dark ash plume, but the ‘biggie’ was sandwiched between numerous other powerful blasts that occurred throughout the weekend:

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More crucially though, particulates ejected to around 32,800 ft (10 km) –and into the stratosphere– can have a direct cooling effect across the planet.

Volcanic eruptions are one of the key forcings driving Earth into its next bout of global cooling. Their worldwide uptick (along with a seismic uptick) is tied to low solar activity, coronal holes, a waning magnetosphere, and the influx of Cosmic Rays penetrating silica-rich magma.