Was Gondwana actually a larger and a true supercontinent? Call it Greater Gondwana

Amazing stuff! What a jigsaw puzzle!

"... Now, Gondwana is posing a new challenge. By studying the age of basement granites known to have existed near the continent’s edge, a team of geologists has found that Gondwana was much bigger than previously thought, encompassing up to 80% of the continental crust at the time, and adding some 127 million square kilometers to its extent. Such size, they suggest, makes it a true supercontinent, nearly on par with Pangea, which formed several hundred million years later.

The finding, if it holds up, challenges the notion of supercontinent cycles—the idea that the continents break apart and smoosh together, driven by shifts in the mantle, in regular cycles of 500 million years or so. ..."

"... Geologists have long gone back and forth on the status of Gondwana, which was discovered more than 100 years ago when common plant fossils were found on widely separated continents.
In 2012, Joseph Meert, a paleogeographer at the University of Florida, concluded supercontinents should at a minimum encompass 75% of all known continental crust. At the time, Gondwana was mostly thought to comprise present-day India, Australia, Africa, Antarctica, and South America—64% of known land. The 75% threshold was always arbitrary ...

But since then, Gondwana’s size has grown, as geologists added continental fragments in the eastern United States, southern Europe, Turkey, Iran, and Pakistan. But other fragments that existed at the time, including much of China, have not traditionally been assigned to Gondwana. Magnetic signals preserved in rocks that can help determine where ancient crust was located are difficult to interpret during this period. The jigsaw puzzle is further complicated by the repeated opening and closing of narrow oceans in East Asia at the time. ..."

From the abstract:

"Profound global biogeochemical shifts marked the Ediacaran-Cambrian transition [550–500 million years (Ma)], a phenomenon often ascribed to the dynamics of supercontinent cycles.

However, Gondwana is frequently denied supercontinent status due to its perceived spatial deficit (∼64% of continental landmass). Leveraging continental-scale Nd isotopic mapping based on a vast database of 25,346 felsic-intermediate igneous rocks, we reveal extensive buried Precambrian terranes beneath Phanerozoic orogens in Asia, Europe, and North America.

Our results expand Gondwana’s reconstructed area to ∼80% of the global landmass, firmly establishing its identity as a true supercontinent—termed “Greater Gondwana.” We propose that the assembly and peripheral subduction of this “Greater Gondwana” played a pivotal role in driving the geodynamic and environmental perturbations that culminated in the Cambrian metazoan radiation."

ScienceAdviser

Pangaea’s ‘little brother’ may finally qualify as a supercontinent

Buried fragments reveal a “Greater Gondwana” supercontinent (open access)

Fig. 1. Continental-scale Nd isotopic (TDM2) map of southwestern Asia, central Europe, and southeastern North America (encompassing peri-Gondwana terranes and orogens).

Fig. 4. Reconstruction of Greater Gondwana at ca. 500 Ma or at 550 to 500 Ma compared with conventional paleogeographic interpretations (inset).

What triggered one of the most dramatic changes in Earth’s history? The ups and downs of oxygen

Amazing stuff!

"... For its first 2 billion years, Earth had almost no free oxygen in its air or oceans. Then, some 2.45 billion years ago, the ancestors of photosynthetic cyanobacteria began to flood the world with oxygen, creating the conditions that allowed complex life to evolve and prosper. The Great Oxidation Event (GOE), as it’s known, is “the most fascinating and most dramatic change in how the Earth’s surface works in its history,”

But that story has clouded recently. Mineral analyses suggest oxygen-producing microbes evolved hundreds of millions of years before the GOE, leaving a huge, unexplained gap when oxygen remained low. And the GOE appears to have been not one event but several, with oxygen repeatedly rising and falling over a span of some 200 million years—a great oxidation followed by a great deoxidation, and then back again, several times. 

Now, possible explanations are emerging.

One talk at the Goldschmidt conference this month proposed that oxygen could not rise until extensive shallow areas formed in the world’s oceans.

Another argued the oxygen pulses reflect ancient Earth’s periodic transformation into Snowball Earth, when ice engulfed the planet to low latitudes. 

Yet a study last year in Nature reported carbonate deposits created by oxygen-producing cyanobacteria 2.85 billion years ago. Using the mutation rates of modern-day microbes to date the origin of photosynthesis pushed it back even further, to as much as 3.5 billion years ago. And for 2 decades, researchers have tracked what appear to be “whiffs” of oxygen prior to the GOE, recorded in minerals that require oxygen to form. ..."

From the abstract of the oral presentation:

"The rise of atmospheric oxygen and the onset of Paleoproterozoic glaciations are commonly attributed to biological innovation, particularly the emergence of oxygenic photosynthesis. Yet geochemical evidence indicates that oxygen production predated the permanent rise of atmospheric O₂, implying that biological capability alone was insufficient to drive sustained oxygenation. Here we present results from a coupled ocean–atmosphere box model demonstrating that continental growth and shelf emergence acted as tectonic gatekeepers of long-term atmospheric redox evolution.

We introduce the concept of a continental oxygen inventory, defined as the product of shallow continental shelf area and dissolved oxygen concentration, to quantify the spatial constraint on oxygen export from the ocean to the atmosphere. Model results reveal two critical thresholds.

When the relative inventory exceeds ~0.01% of its modern value, atmospheric O₂ surpasses the mass-independent sulfur fractionation (S-MIF) threshold (~10⁻⁵ PAL).

When it exceeds ~1%, enhanced methane oxidation drives atmospheric CH₄ collapse, triggering global glaciation. Below these thresholds, even oxygenated surface waters fail to oxygenate the atmosphere.

Because shelf area is ultimately controlled by continental crust volume, mantle thermal state, plate mobility, and hypsometry, these results imply that deep Earth processes fundamentally regulated the timing and magnitude of atmospheric oxygenation. The Great Oxidation Event, therefore reflects not solely biological innovation but the progressive expansion of oxygen-producing habitats enabled by tectonic evolution during late Archean–early Proterozoic continental growth.

More broadly, this work highlights tectonics as a first-order control on planetary oxidation state and climate stability. By linking mantle dynamics to atmospheric composition through evolving continental geometry, our framework reframes Earth’s oxygenation as a coupled deep Earth–surface process. These findings have implications not only for interpreting the tempo of Earth’s environmental and biological evolution, but also for assessing the likelihood of atmospheric oxygen accumulation—and thus detectable biosignatures—on rocky exoplanets with differing tectonic regimes."

What triggered one of the most dramatic changes in Earth’s history? | Science | AAAS

Continental Growth as a Tectonic Gatekeeper of Early Earth Oxygenation (an oral presentation)

How did mammals from North America move into South America millions of years ago

Amazing stuff!

"... researchers have found fossil evidence that animals from different latitudes of North America and South America mixed long before the Panamanian land bridge permanently linked the two continents about 3 million years ago.

Since around 10 million years ago, mammals — primarily small ones like sloths and coatis — found a way across the watery barrier. Only larger mammals had to wait for the permanent land corridor. ...

Biologists thought that only after the isthmus formed did animals surge north and south, what biologists refer to as the Great American Biotic Interchange or GABI. That resulted in the extinction of a lot of South American species as North American species took over.

Yet this picture of mammal movements across continents is too simple, ... paleontologists argue. After assembling and analyzing a new database of fossil mammals discovered in Mexico, they conclude that northern North American animals had already migrated into southern North America by about 10 million years ago, where they waited around in a kind of holding pen until opportunities arose for some of them to continue crossing to the south starting about 7 million years ago. ...

During that pre-GABI time, smaller mammals — heralded by racoon-like coatis and ringtails and small rodents — moved to South America via some kind of intermittent corridor, by island hopping through the Caribbean or by rafting on vegetation. Only one major South American group, the sloths, moved to North America. ..."

From the abstract of the Perspective:

"Whenever plants and animals newly come together, there will be some winners and some losers. This was the case for the Great American Biotic Interchange (GABI), which occurred ~2.8 million years ago (Ma), when the emergence of the Isthmus of Panama connected the continents of South and North America. Although species moved both northward and southward during the GABI, a massive taxonomic asymmetry arose between the two continents, with a much greater proportion of species in South America having a North American origin than the opposite. ... Tseng et al. report that a large fossil dataset from Mexico helps to uncover the events that primed mammals for movement across the Isthmus."

From the editor's summary and abstract:

"Editor’s summary

For millions of years after the breakup of the supercontinent Gondwana, South America was disconnected from other landforms, a time period that has been referred to as its “splendid isolation.”

This isolation allowed for the evolution of mammals with distinctive features, including xenarthrans, sprassodont carnivores, and notoungulates.

The formation of the Panamanian land bridge facilitated connection of North and South American faunas, with a bias from north to south. Tseng et al. looked at fossils from low latitudes in México and found that northern mammals accumulated in the region before the connection (see the Perspective by McGuire and Williams). This allowed for more rapid dispersal south and further supports that the land bridge first formed during the Pliocene rather than the Miocene. ...

Abstract

The movement of taxa between North and South America across the Panamanian land bridge, known as the Great American Biotic Interchange (GABI), established modern-day mammal assemblages in the Americas, heralding the decisive end of what has been called the “splendid isolation” of the South American fauna.

Lacking substantive low-latitude records, previous work on this pattern relied on South American and temperate North American fossils to conclude that pulsed interchanges began about 2.8 million years ago (mya).

Based on new low-latitude fossil data from México, we found evidence for a prolonged, triphasic interchange.

Phase 1 consisted of the initial accumulation of northern higher-latitude mammals in a Mexican “holding pen” beginning 10 mya. 

Dispersal began in phase 2, with a strong north-south gradient and increasing biogeographic connections (7 to 3 mya).

The final phase consisted of the already well-described taxonomic pulses (from ~2.8 mya)."

ScienceAdviser

When mammals crossed between continents (no public access)

North and South America weren’t always connected, but their mammals still found a way to intermingle (original news release) "Before the Panamanian land bridge formed about 3 million years ago, mammals on the two continents were isolated — or so biologists thought. New fossils show that they found ways to mix long before that."

A 10-million-year biogeographic holding pen primed the Great American Biotic Interchange (no public access) "Before the Panamanian land bridge formed about 3 million years ago, mammals on the two continents were isolated — or so biologists thought. New fossils show that they found ways to mix long before that."

This illustration depicts (left) large North American mammals — counterclockwise from top, mammoths, llamas, tapirs, peccaries and saber-toothed cats — waiting in a kind of holding pen in Mexico for the bridge to form.

In South America, the mammalian interchange involved, counterclockwise from top, ground sloths, marsupials, capybaras, armadillos, glyptodonts and, incidentally, terror birds. While North American mammals took over in South America, only about 10% of North American mammals today are derived from mammals that originated in South America.

Deep-Earth map reveals a lost U.S. continent

Amazing stuff!

Too bad, I was not able to find an image of this former continent using Google and Bing search.

"Along the eastern front of the Appalachian Mountains, buried just below the surface, lies a fragment of a lost continent. Running from Maine to Georgia, the 200-kilometer-thick slab of crust was probably created by volcanic eruptions during the breakup of the Pangaea supercontinent some 200 million years ago and later buried by silt from eroding mountains.

Known as the Piedmont Resistor, this piece of Pangaea is one of the signature discoveries of the Magnetotelluric (MT) Array, 1800 temporary stations scattered across the contiguous United States that measured the conductivity of deep rocks. Now, 20 years after it started, the MT Array has released its final map and model ... It shows how the assembly of the continent left hidden structures such as the Piedmont Resistor—and mineral riches. ..."

From the abstract:

"The United States Magnetotelluric Array (USMTArray) data set, collected in the years 2006–2024, consists of more than 1,700 long-period magnetotelluric stations covering the entirety of the contiguous United States on a quasi-regular 70 km grid. ...

Together with parallel advancement in the development of publicly available three-dimensional (3D) inversion codes, the USMTArray has revitalized the US magnetotelluric community and increased the visibility of magnetotellurics within the Earth-science community.

Taken as a whole, these data are visualized as the National Impedance Map, which, together with a 3D synthesis conductivity model of the nation, reveals the electrical architecture of the contiguous US. USMTArray data are used by researchers worldwide for fundamental and applied studies, including investigations of continental architecture and evolution, estimation of hazards to critical infrastructure due to geomagnetic storms, and assessment of the nation's undiscovered geothermal and mineral resources.

We here review the history and development of the project, discuss the challenges and successes in its execution, present the National Impedance Map and synthesis conductivity model, and highlight the breadth of research stemming from this rich data set."

Deep-Earth map reveals a lost U.S. continent | Science | AAAS "Sensor array traces how rocks conduct electricity, exposing ancient continental fragments, mineral targets, and grid hazards"

The United States Magnetotelluric Array and the National Impedance Map (open access)

Plate tectonics is even older than we thought

Amazing stuff!

The author of the Perspective abstract below is obsessed with Global Warming/Climate Change: "The movement of tectonic plates—massive slabs of rock—over Earth’s surface controls the planet’s habitability by sustaining the carbon cycle that regulates the climate" (The first sentence of the abstract) I have serious doubts that this is correct!

From the Perspective abstract:

"The movement of tectonic plates—massive slabs of rock—over Earth’s surface controls the planet’s habitability by sustaining the carbon cycle that regulates the climate [???] and stabilizes liquid water at the surface .
It also facilitates efficient planetary heat loss, thereby maintaining convection in Earth’s core and the generation of a magnetic field. The presence of a magnetosphere—a space around Earth dominated by its magnetic field—provides shielding from solar and cosmic radiation and mediates the loss of atmospheric gas into space. Deciphering plate motions in Earth’s early history can thus hint at how the planet looked several billion years ago. On page 1278 of this issue, Brenner et al. (2) report differential plate motion 3.5 billion years (Ga) ago by recovering ancient magnetic field records from rocks in Australia. This may provide clues to the nature of early tectonic motions and their role in sustaining habitable conditions."

From the editor's summary and abstract:

"Editor’s summary

Plate tectonics is a global recycling process that underpins most of Earth’s systems. Its onset remains an open question because of sparse early geologic records. Brenner et al. collected paleomagnetic data from approximately 3.4 billion-year-old rocks in Western Australia and compared them with existing data from rocks of the same age in South Africa (see the Perspective by Nichols). They detected diverging paleolatitudes, two crustal blocks moving differently around the same magnetic pole. The rate of motion is consistent with aspects of modern plate tectonics but could reflect an earlier style. This plate motion was occurring against the backdrop of the oldest known geomagnetic reversal, which was also discovered from these data.

Abstract

Whether early Earth had a mobile lithosphere and plate tectonics is debated. We present paleomagnetic data quantifying differential motion between lithospheric blocks at ~3.48 billion years ago (Ga). This manifested as 

centimeters per year latitudinal motion of the East Pilbara Craton (Western Australia) across high latitudes, whereas the Barberton Greenstone Belt (South Africa) was stationary at low latitudes. Comparison of this plate motion with candidate analogs suggests either rapid collisional plate tectonics (i.e., an “active-lid”) or an episodically mobile lithosphere. We also document the oldest known geomagnetic reversal at ~3.46 Ga, consistent with an axial dipolar dynamo that reversed less frequently than today’s. The existence and rates of these surface and core geophysical phenomena provide geodynamic context to Earth’s early geophysical and biological evolution."

ScienceAdviser

Ancient rocks reveal early plate motions (Perspective, no public access)

Paleomagnetic detection of relative plate motions and an infrequently reversing core dynamo at 3.5 Ga (no public access)

Scientists detect deep Earth molten mantle rock pulses beneath the Afar region in Ethiopia

Amazing stuff! Out of Africa!

"Research ... has uncovered evidence of rhythmic surges of molten mantle rock rising from deep within the Earth beneath Africa. These pulses are gradually tearing the continent apart and forming a new ocean.

The findings ... reveal that the Afar region in Ethiopia is underlain by a plume of hot mantle that pulses upward like a beating heart. ...

"We found that the mantle beneath Afar is not uniform or stationary—it pulses, and these pulses carry distinct chemical signatures. These ascending pulses of partially molten mantle are channeled by the rifting plates above. That's important for how we think about the interaction between Earth's interior and its surface." ...

The Afar region is a rare place on Earth where three tectonic rifts converge: the Main Ethiopian Rift, the Red Sea Rift, and the Gulf of Aden Rift. ..."

From the abstract:

"Mantle upwellings drive large-scale surface volcanism and facilitate continental breakup and ocean basin formation. However, the spatial characteristics and internal composition of these upwellings alongside how they are modified by plate tectonics are poorly resolved.

Afar, East Africa, is a classic triple junction comprising three rifts at various stages of evolution thought to be underlain by a mantle upwelling or plume, allowing examination of the controls on the mantle upwelling.

Here we present geochemical data from >130 samples of ‘young’ volcanoes spanning the rifts defining the triple junction to show that the underlying mantle comprises a single, asymmetric upwelling.

Using statistical modelling to integrate our data with existing geochemical and geophysical constraints, we suggest that Afar is fed by a spatially and chemically heterogeneous upwelling, which controls the composition and relative abundance of melt in all three rift arms.

We identify repetitive signatures in mantle compositions in rift regions, whose variability is a longer wavelength in faster-extending rift arms. This suggests more rapid channelized mantle flow occurs where rifting rates are higher and the plate is thinner, aiding flow of the upwelling towards the faster-spreading Red Sea Rift. Our findings demonstrate how the evolution of mantle upwellings is influenced by the dynamics of overriding plates."

Scientists detect deep Earth pulses beneath Africa

Scientists detect deep Earth pulses beneath Africa (original news release)

Mantle upwelling at Afar triple junction shaped by overriding plate dynamics (open access)

Fig. 1: Variation in geochemical and geophysical properties around the Afar Triangle.

Fig. 6: Spatially heterogeneous nature of the mantle upwelling beneath Afar.

Active lava flows spilling out of the Erta Ale volcano in Afar, Ethiopia.

Extensive ocean floor mapping via satellite of the still poorly charted seafloor

Amazing stuff! However, an 8-kilometer spatial resolution is not too impressive.

"... researchers using data from a cutting-edge satellite released a new map of the global seafloor charting more than 200,000 of these [abyssal] hills. Launched two years ago by NASA and CNES, France’s national space agency, the Surface Water and Ocean Topography (SWOT) satellite is primarily meant to map the height of ocean swirls and rivers in fine detail. But by looking at subtle ways water piles about these large seafloor features due to gravity, it can also map the abyss.

After just one year, seafloor maps created by SWOT have already outpaced those assembled from decades of older technology. With only 25% of the ocean bottom mapped by sonar, the SWOT maps will fill critical gaps for decades to come. And in particular, its view of the abyssal hills—one of the fundamental fabrics of Earth’s surface—will allow plate tectonics to be studied in fine detail, perhaps triggering a new boom in the field. ..."

From the perspective abstract:

"Global marine gravity fields—variations in Earth’s gravitational pull across the ocean surface—provide valuable information about seafloor topography and plate tectonics beneath the water, knowledge that is essential for understanding geological features and ocean dynamics.

A technique that estimates Earth’s surface heights from space, called satellite altimetry, has partially resolved marine gravity fields. However, conventional altimetry can only obtain one-dimensional measurements along a satellite track. The 2022 Surface Water and Ocean Topography (SWOT) mission marked a considerable advancement in satellite altimetry because it captures two-dimensional, large-area topography data with high precision (3). On page 1251 of this issue, Yu et al. (4) report that a gravity field derived from 1 year of SWOT data reveals plate tectonics along the deep ocean floor that had remained hidden for the past 30 years with conventional altimeter observations. This level of detail could improve understanding of ocean environment and dynamics."

From the editor's summary and abstract:

"Editor’s summary

Detailed maps of the ocean floor come from ship crossings but can also be obtained using satellite altimetry. Yu et al. used radar altimetry observations from just 1 year of the Surface Water and Ocean Topography mission to develop a high-resolution global seafloor map ... The new satellite observations have a resolution about twice that of the older observations, presenting an opportunity to better understand the geological features of the seafloor. ...

Abstract

The global ocean covers 71% of Earth’s surface, yet the seafloor is poorly charted compared with land, the Moon, Mars, and Venus. Traditional ocean mapping uses ship-based soundings and nadir satellite radar altimetry—one limited in spatial coverage and the other in spatial resolution. The joint NASA–CNES (Centre National d’Etudes Spatiales) Surface Water and Ocean Topography (SWOT) mission uses phase-coherent, wide-swath radar altimetry to measure ocean surface heights at high precision. We show that 1 year of SWOT data offers more detailed information than 30 years of satellite nadir altimetry in marine gravity, enabling the detection of intricate seafloor structures at 8-kilometer spatial resolution. With the mission still ongoing, SWOT promises critical insights for bathymetric charting, tectonic plate reconstruction, underwater navigation, and deep ocean mixing."

ScienceAdviser

Transforming coastal mapping from space (no public access)

Abyssal marine tectonics from the SWOT mission (no public access)

The parallel ridges of abyssal hills, as seen by the Surface Water and Ocean Topography satellite, extend out from the flanks of a seafloor spreading center (black lines) in the Indian Ocean. 

Geologists discover mysterious subduction zone beneath Pacific, reshaping understanding of Earth's interior

Amazing stuff!

We do not even yet understand the geology of our planet very well, but we are inundated on a daily basis with a barrage of climate change propaganda and demagoguery! Even many scientists can not resist to chime in for more money or for lack of genius or being like idiot savants (Very peculiar Wikipedia eliminated or omitted this famous term. A case of political correctness?)!

"... scientists uncovered evidence of an ancient seafloor that sank deep into Earth during the age of dinosaurs, challenging existing theories about Earth's interior structure. Located in the East Pacific Rise (a tectonic plate boundary on the floor of the southeastern Pacific Ocean), this previously unstudied patch of seafloor sheds new light on the inner workings of our planet and how its surface has changed over millions of years. ...

They found an unusually thick area in the mantle transition zone, a region located between about 410 and 660 kilometers below the Earth's surface. The zone separates the upper and lower mantles, expanding or contracting based on temperature. The team believes that the newly discovered seafloor may also explain the anomalous structure of the Pacific Large Low Shear Velocity Province (LLSVP)—a massive region in Earth's lower mantle—as the LLSVP appears to be split by the slab. ...

What the team found surprised them—material was moving through Earth's interior much more slowly than previously thought. Wang believes that the unusual thickness of the area the team discovered suggests the presence of colder material in this part of the mantle transition zone, hinting that some oceanic slabs get stuck halfway down as they sink through the mantle. ..."

From the abstract:

"The Pacific large low-shear-velocity province (LLSVP), as revealed by cluster analysis of global tomographic models, hosts multiple internal anomalies, including a notable gap (~20° wide) between the central and eastern Pacific. The cause of the structural gap remains unconstrained. Directly above this structural gap, we identify an anomalously thick mantle transition zone east of the East Pacific Rise, the fastest-spreading ocean ridge in the world, using a dense set of SS precursors. The area of the thickened transition zone exhibits faster-than-average velocities according to recent tomographic images, suggesting perturbed postolivine phase boundaries shifting in response to lowered temperatures. We attribute this observation to episodes of Mesozoic-aged (250 to 120 million years ago) intraoceanic subduction beneath the present-day Nazca Plate. The eastern portion of the Pacific LLSVP was separated by downwelling because of this ancient oceanic slab. Our discovery provides a unique perspective on linking deep Earth structures with surface subduction."

Geologists discover mysterious subduction zone beneath Pacific, reshaping understanding of Earth's interior

UMD Geologists Discover Ancient Sunken Seafloor From Dinosaur Era (original news release) "Zone Beneath Pacific Ocean Reveals How ‘Recycling’ Deep Within the Earth May Influence Surface Features"

Mesozoic intraoceanic subduction shaped the lower mantle beneath the East Pacific Rise (open access)

A map depicting the region where the discovery of an ancient seafloor was made.

Fig. 5. Interpreted evolution of the SEPR anomaly.

Mount Everest is Growing Even Taller. Here’s why with Palki Sharma

Recommendable!

When India Was An Island

Very recommendable!

Plate tectonics: Marine biodiversity booms cyclically every 36 million years

Amazing stuff!

"... The scientists' findings challenge prior theories of why species have evolved over vast periods. According to Müller, the cycles are 36 million years long due to regular patterns in how tectonic plates are recycled into the convecting mantle ...

It is this geological clock, intertwined with sea-level changes, that shapes the evolution and extinction of marine species over millions of years. But it is far from being alone.

Scientists discovered evidence of another 62-million-year biodiversity cycle. This time, this cycle could be linked to shifts in carbon dioxide levels. ..."

"Movement in the Earth's tectonic plates indirectly triggers bursts of biodiversity in 36-million-year cycles by forcing sea levels to rise and fall, new research has shown. ...
As water levels rise and fall, different habitats on the continental shelves and in shallow seas expand and contract, providing opportunities for organisms to thrive or die. By studying the fossil record, the scientists have shown that these shifts trigger bursts of new life to emerge. ..."

From the significance and abstract:

"Significance

The evolution of life on Earth has changed dramatically at tens of million-year (Myr) time scales. However, the causal mechanisms of these biotic changes remain conjectural. Here, we show evidence of cycles of tens of Myr in marine animal fossil data over the last 250 Myr. We find similar, correlatable cycles in sea-level and Earth’s interior processes, suggesting that long-term marine biodiversity was paced by geodynamically driven global sea-level cycles. We argue that biotic diversity has fluctuated by quasi-cyclical continental flooding and retreat of the ocean, expanding and contracting ecological niches on shelves and on epeiric seas.

Abstract

The fossil record reveals that biotic diversity has fluctuated quasi-cyclically through geological time. However, the causal mechanisms of biotic diversity cycles remain unexplained. Here, we highlight a common, correlatable 36 ± 1 Myr (million years) cycle in the diversity of marine genera as well as in tectonic, sea-level, and macrostratigraphic data over the past 250 Myr of Earth history. The prominence of the 36 ± 1 Myr cycle in tectonic data favors a common-cause mechanism, wherein geological forcing mechanisms drive patterns in both biological diversity and the preserved rock record. In particular, our results suggest that a 36 ± 1 Myr tectono-eustatically driven sea-level cycle may originate from the interaction between the convecting mantle and subducting slabs, thereby pacing mantle-lithospheric deep-water recycling. The 36 ± 1 Myr tectono-eustatic driver of biodiversity is likely related to cyclic continental inundations, with expanding and contracting ecological niches on shelves and in epeiric seas."

Marine biodiversity booms every 36 million years like clockwork. Here's why (Secondary source again does not mention the primary source) Life on Earth booms every 36 million years, driven by tectonic cycles.

Scientists discover 36-million-year geological cycle that drives  biodiversity (Primary source) Tectonic changes alter sea levels that can create breeding grounds for life

Earth’s interior dynamics drive marine fossil diversity cycles of tens of millions of years (no public access)

The Invisible Barrier Keeping Two Worlds Apart in Indonesia

Very recommendable! Amazing stuff!

Imaging ancient ocean seafloors sunk to the core-mantle boundary

Amazing stuff!

"Through global-scale seismic imaging of Earth’s interior, research ... revealed a layer between the core and the mantle that is likely a dense, yet thin, sunk ocean floor ...
Seen only in isolated patches previously, the latest data suggests this layer of ancient ocean floor may cover the core-mantle boundary. Subducted underground long ago as the Earth’s plates shifted, this ultra-low velocity zone, or ULVZ, is denser than the rest of the deep mantle, slowing seismic waves reverberating beneath the surface.
Seismic investigations, such as ours, provide the highest resolution imaging of the interior structure of our planet, and we are finding that this structure is vastly more complicated than once thought,” ...

Understanding the composition of the core-mantle boundary on a large scale is difficult, but a seismic network deployed ... to Antarctica collected data for three years. Similar to a medical scan of the body, the 15 stations in the network buried in Antarctica used seismic waves created by earthquakes from around the globe to create an image of the Earth below.

The project was able to probe in high-resolution a large portion of the southern hemisphere for the first time using a detailed method that examines sound wave echoes from the core-mantle boundary. Hansen and the international team identified unexpected energy in the seismic data that arrives within several seconds of the boundary-reflected wave. ...

These subtle signals were used to map a variable layer of material across the study region that is pencil thin, measuring in the tens of kilometers, compared to the thickness of the Earth’s dominant layers. The properties of the anomalous core-mantle boundary coating include strong wave speed reductions, leading to the name of ultra-low velocity zone.

ULVZs can be well explained by former oceanic seafloors that sunk to the core-mantle boundary. Oceanic material is carried into the interior of the planet where two tectonic plates meet and one dives beneath the other, known as subduction zones. Accumulations of subducted oceanic material collect along the core-mantle boundary and are pushed by the slowly flowing rock in the mantle over geologic time. The distribution and variability of such material explains the range of observed ULVZ properties. ..."

From the absract:

"Ultralow velocity zones (ULVZs) are the most anomalous structures within the Earth’s interior; however, given the wide range of associated characteristics (thickness and composition) reported by previous studies, the origins of ULVZs have been debated for decades. Using a recently developed seismic analysis approach, we find widespread, variable ULVZs along the core-mantle boundary (CMB) beneath a largely unsampled portion of the Southern Hemisphere. Our study region is not beneath current or recent subduction zones, but our mantle convection simulations demonstrate how heterogeneous accumulations of previously subducted materials could form on the CMB and explain our seismic observations. We further show that subducted materials can be globally distributed throughout the lowermost mantle with variable concentrations. These subducted materials, advected along the CMB, can provide an explanation for the distribution and range of reported ULVZ properties."

Beneath the Earth, Ancient Ocean Floor Likely Surrounds the Core – University of Alabama News | The University of Alabama

Globally distributed subducted materials along the Earth’s core-mantle boundary: Implications for ultralow velocity zones (open access)

Credits: An ancient ocean floor has landed next to the Earth's core, says study

In this representation of the underground imaging, seismic waves from earthquakes in the southern hemisphere sample the ULVZ structure along the Earth’s core-mantle boundary and are recorded by sensors in Antarctica

That Time the American West Blew Up

Very recommendable! Dedicated to all those who believe in a "climate crisis"! Learn how quickly life recovers despite a cataclysmic catastrophe!

Modeling predicts supercontinent Amasia will form in 300 million years

Amazing stuff! Will humans still be around to witness it? 

Which of the oceans will ultimately close next time to form a supercontinent, the Pacific Ocean, the Atlantic Ocean, or both together, or the Indian ocean?

Will plate tectonics ever stop or slow down? Quite possible!

"New modeling from researchers at Curtin University has simulated 300 million years of tectonic plate movement to predict the formation of a supercontinent called Amasia. The modeling estimates the Pacific Ocean closing and America colliding with Asia. ...
“Over the past two billion years, Earth’s continents have collided together to form a supercontinent every 600 million years, known as the supercontinent cycle,” ...
The most recent supercontinent was Pangaea, which came together around 335 million years ago and began to break up at the beginning of the Jurassic age 200 million years ago. ...
But unsurprisingly, there are plenty of hypotheses speculating how the world’s continents will shift over the next few hundred million years. One configuration, dubbed Pangaea Proxima, suggests the Atlantic and Indian oceans will ultimately close, creating a supercontinent not entirely unlike Pangaea. Another hypothesis proposes the Atlantic and Pacific oceans will both close, with a rift splitting Eurasia from India to the Arctic creating a supercontinent called Aurica. ..."

From the abstract:

"Earth's known supercontinents are believed to have formed in vastly different ways, with two end members being introversion and extroversion. The former involves the closure of the internal oceans formed during the break-up of the previous supercontinent, whereas the latter involves the closure of the previous external superocean. However, it is unclear what caused such a diverging behavior of supercontinent cycles that involved first-order interaction between subducting tectonic plates and the mantle. Here we address this question through 4-D geodynamic modeling using realistic tectonic setups. Our results show that the yield strength of the oceanic lithosphere plays a critical role in determining the assembly path of a supercontinent. We found that high oceanic lithospheric strength leads to introversion assembly, whereas lower strength leads to extroversion assembly. A theoretically estimated reduction in oceanic crustal thickness, and thus its strength, during Earth's secular cooling indicates that introversion was only possible for the Precambrian time when the oceanic lithosphere was stronger, thus predicting the assembling of the next supercontinent Amasia through the closure of the Pacific Ocean instead of the Indian-Atlantic oceans. Our work provides a new understanding of the secular evolution of plate tectonics and geodynamics as the Earth cooled."

Modeling predicts supercontinent Amasia will form in 300 million years

Pacific Ocean set to make way for world’s next supercontinent New Curtin University-led research has found that the world’s next supercontinent, Amasia, will most likely form when the Pacific Ocean closes in 200 to 300 million years.

Will Earth's next supercontinent assemble through the closure of the Pacific Ocean? (open access)

How the Earth-shaking theory of plate tectonics was born

Recommendable! An historical overview of how a once controversial idea became accepted!

How the Earth-shaking theory of plate tectonics was born | Science News