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Impact Craters On Our Earth

The oldest impact may have had a beneficial effect.

BARCELONA, SPAIN—Barlangi Rock, an ancient hill in the outback of Western Australia, is dimpled by the quarries of Aboriginal people who chiseled its fine-grained rocks into sharp tools. Now, geologists have added a much deeper layer of history to those rocks by showing they were forged 2.229 billion years ago, when an asteroid crashed into our planet. The finding makes Yarrabubba crater, the 70-kilometer-wide scar left by the collision, Earth’s oldest.

The geologists who reported the date last week, here at the Goldschmidt geochemistry conference, also point out a conspicuous coincidence: The impact came at the tail end of a planetwide deep freeze known as Snowball Earth. They say the impact may have helped thaw Earth by vaporizing thick ice sheets and lofting steam into the stratosphere, creating a powerful greenhouse effect.

https://www.sciencemag.org/news/2019/08/shock-and-thaw-earth-s-oldest-asteroid-impact-may-have-helped-lift-planet-out-deep
 
This research on the Swedish Siljan Ring crater indicates that the deeply shattered rock at such sites provides a viable environment for deep-dwelling microbes.

Even though the Siljan Ring impactor didn't arrive bearing extraterrestrial life, it seems to have been beneficial for terrestrial organisms.

Ancient microbes are living inside Europe's deepest meteorite crater

Rock cores collected from deep beneath the planet's surface suggest ancient microbes have been living inside Europe's largest meteorite crater for millions of years.

Some 400 million years ago, a massive space rock slammed into northern Europe, excavating a giant crater in the middle of what's now Sweden. Today, prospectors are drilling for natural gas within the confines of the ancient crater, the contours of which are called the Siljan Ring.

The drilling attempts have yielded fresh rock cores, several of which made their way to geochemistry labs at Linnaeus University in Sweden.

When scientists at Linnaeus investigated the rocks, they found evidence of long-term deep microbial activity. ...

Using radioisotopic dating techniques, scientists were able to determine that microbes were cycling methane during the formation tiny calcite crystals, and that the activity occurred between 80 and 22 million years ago. ...

Scientists have long theorized that ancient asteroid and comet impacts could have delivered the ingredients for early life forms to Earth, or perhaps even shepherded already thriving microbial communities from distant planets to ours. But the latest research -- published this week in the journal Nature Communications -- suggests the microbes living deep inside the Siljan crater arrived after the impact event.

"At Siljan we see that the crater is colonized but that it has mainly occurred when conditions, such as temperature, became more favorable than at the impact event," Drake said. "The impact structure itself, with a ring zone of down-faulted Paleozoic sediments, has been optimal for deep colonization, because organics and hydrocarbons from shales have migrated throughout the fractured crater and have acted as energy sources for the deep microbial communities." ...

But while the latest investigation didn't reveal evidence of alien microbes, it did offer proof that impact craters can serve as prime real estate for ancient microbe colonies.
FULL STORY: https://www.upi.com/Science_News/20...est-meteorite-crater/8901571414891/?rc_fifo=2
 
Could this asteroid have brought life to earth? This event coincides with the emergence of the Ediacaran - earliest life forms discovered.


https://www.abc.net.au/news/science...rk-australias-extreme-geological-past/8728928
Lake Acraman: A crater of cataclysmic proportions
Looking down from space, Lake Acraman seems innocuous enough on the gentle slopes of the northern Eyre Peninsula in South Australia. But its circular shape hints at a truly cataclysmic origin.

GIF: the asteroid-eye-view as it speeds to the earth
Lake Acraman is the site of one of the largest meteorites to strike our planet. Source: Google Earth


This lake is actually the eroded remains of a giant meteorite impact crater that is 580 million years old and estimated to be up to 90 kilometres wide — one of the largest craters ever identified.
No surprises then that the impact energy was equivalent to more than 5 million megatons of TNT; enough to produce a global catastrophe that included seismic shocks, tsunamis and super-hurricanes.
Material ejected from the crater has been identified more than 300 kilometres east in rocks of the Flinders Ranges.

Pink fragments of pulverised granite ejected from a meteorite crater

(Supplied: Ian Clark)
Here, features such as shatter cones, shocked quartz and pulverised rock fragments are seen within a distinctive sedimentary layer known as an ejecta horizon.
Today the crater is much flatter than when it first formed, with up to 5 kilometres of material stripped off its surface over time — yet it still remains as the unmistakeable imprint of an extraterrestrial visitor that entered with a giant bang!


From the youtube descriptor for the above video:
Victor Gostin describes his work in Outback Australia, piecing together the various clues that led to his understanding of the enormous impact of the 5km asteroid at Lake Acraman, Eyre Peninsula, South Australia. He relates the fascinating story of how he and his colleagues discovered volcanic material in the Flinders Ranges and linked it with the impact into volcanic rocks at Lake Acraman, some 300 kilometres away. His discovery was linked to a previous discovery by George Williams, now also at the University of Adelaide, that an impact scar at Lake Acraman was due to the impact of an ancient large asteroid. Victor Gostin describes the process he went through to find that material found at both sites were similar in lithology, fracturing, and age, showing that the ejecta in the Flinders Ranges came from the Lake Acraman impact.
 
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Could this asteroid have brought life to earth?

No ... The oldest definitive evidence of simple biological life on earth pre-dates the Lake Acraman impact by circa 3 billion years. Accepting more recent strongly suggestive evidence would push that horizon back to over 4 billion years ago.


This event coincides with the emergence of the Ediacaran - earliest life forms discovered. ...

The Ediacaran is the period during which the earliest complex multicellular organisms are known to have been present (based on evidence to date). These represent the earliest multicellular organisms with differentiated / specialized internal tissues (as opposed to a collective comprised of one type of cell).
 
Thanks. Gostin supposes that the Acraman event coinciding with Ediacaran glaciation could have caused a biotic crisis which stimulated biotic evolution.
 
Thanks. Gostin supposes that the Acraman event coinciding with Ediacaran glaciation could have caused a biotic crisis which stimulated biotic evolution.

That may well have happened. It's been known for a long time that the Ediacaran glaciation had global ecological and biological ramifications. The effects of an impactor the apparent size of the Lake Acraman whatever-it-was would have been an additional destabilizing factor.

Not much is known about the Ediacaran biota and how they relate to the later Cambrian organisms. The available evidence can support either (a) a relatively abrupt global shift from the earlier to the later forms or (b) some sort of less dramatic evolutionary progression for which we've not yet found any evidence.
 
re EG's correction above;
Nearby quartzite rocks contain Ediacaran fossils, the oldest soft-bodied organisms ever discovered.
8732190-3x2-large.jpg

The Ediacaran Period is named after the hills that contain these fossils, and is indicated by a bronze plaque known as a golden spike — the only one in the Southern Hemisphere.

Source = previous ABC link

Just as an aside, I stumbled upon the Golden Spike quite by accident roaming near the Trezona campground a few years ago. What a moment. I was heading back there yesterday when my car engine shat itself and I had to turn around and come home.
 
Not much is known about the Ediacaran biota and how they relate to the later Cambrian organisms. The available evidence can support either (a) a relatively abrupt global shift from the earlier to the later forms or (b) some sort of less dramatic evolutionary progression for which we've not yet found any evidence.
I am considering heading in that direction professionally in life 2.0. Geological time fascinates me deeply.
 
A new analysis indicates the Wolfe Creek Crater (in Western Australia) is less than half as old as previously believed ...
New Analysis Just Changed The Original Date of a Massive Meteorite Crater in Australia

In the state of Western Australia sits the famous Wolfe Creek crater, the aftermath of a 14,000-tonne meteorite crashing into Earth thousands of years ago. A new study now claims the impact happened far more recently than we suspected, prompting a rethink on how often giant space rocks actually strike our planet.

A team of researchers from universities in Australia and the US took a close look at several features of the crater's underlying rock to get a precise measurement on the age of Wolfe Creek's most famous landmark.

Previous estimates have stated the crater could be 300,000 years old, but the new result places it much closer to our time, perhaps as little as 120,000 years ago. ...
FULL STORY: https://www.sciencealert.com/one-of...med-far-more-recently-than-previously-thought
 
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Crater found from asteroid that covered 10% of Earth's surface in debris

The crater sits beneath a plain of hardened lava that formed after the asteroid impact, which occurred nearly 800,000 years ago.

Source: Astronomy online
Date: 3 January, 2020

A flash of light would have come first, followed by a shockwave and massive earthquake. Only later would the hailstorm of black, glassy debris begun to fall, a rocky rain that would touch ten percent of the planet's surface.

That's the scene that followed a massive asteroid impact 790,000 years ago. The remains it scattered, called tektites, have been found from Asia to Antarctica. For decades, scientists have searched for the elusive resting place of the impactor that coated the Earth with debris. Now, they may have finally found it.

A new report published in the Proceedings of the National Academy of Sciences says that the meteorite likely struck in southern Laos, carving a 10.5 by eight mile crater now covered by a lava flow.

The find helps reconstruct some of the chaos that ensued after impact, says study co-author Kerry Sieh, a geologist at Nanyang Technological University in Singapore. It could also illustrate some of what we could expect if a similarly large asteroid were to hit Earth again.

https://astronomy.com/news/2020/01/...d-that-covered-10-of-earths-surface-in-debris
 
... Now, geologists have added a much deeper layer of history to those rocks by showing they were forged 2.229 billion years ago, when an asteroid crashed into our planet. The finding makes Yarrabubba crater, the 70-kilometer-wide scar left by the collision, Earth’s oldest. ...

Newly-published research has confirmed the age of the Yarrabubba crater and its status as the oldest known impact site on our planet.

Overview:
https://www.sciencealert.com/a-crater-in-australia-is-earth-s-oldest-known-meteoroid-impact

Published report:
https://www.nature.com/articles/s41467-019-13985-7
 
At the time of its discovery we didn't note the 8- km wide Bow City crater in Alberta. It was formed circa 70 million years ago, and the crater structure had been buried and eroded over time so as to prevent detecting it on the surface.
Ancient Impact Crater Discovered in Canada

May 8, 2014 by News Staff

Scientists from Alberta Geological Survey and the University of Alberta have discovered an 8 km wide bowl-shaped impact crater near Bow City in southern Alberta.

“We know that the impact occurred within the last 70 million years, and in that time about 1.5 km of sediment has been eroded. That makes it really hard to pin down and actually date the impact,” said Dr Douglas Schmitt of the University of Alberta, a co-author of the paper published in the journal Meteoritics & Planetary Science.

“Time and glaciers have buried and eroded much of the evidence, making it impossible at this point to say with full certainty the ring-like structure was caused by a meteorite impact, but that’s what seismic and geological evidence strongly suggests.”

Erosion has worn away all but the roots of the crater, leaving a semicircular depression with a central peak. When the crater formed, it likely reached a depth of 1.6 to 2.4 km.

“An impact of this magnitude would kill everything for quite a distance,” said Wei Xie, a graduate student at the University of Alberta and a co-author on the study.

“If it happened today, Calgary (200 km to the northwest) would be completely fried and in Edmonton (500 km northwest), every window would have been blown out.”

“Something of that size, throwing that much debris in the air, potentially would have global consequences; there could have been ramifications for decades.”

SOURCE: http://www.sci-news.com/geology/science-bow-city-impact-crater-canada-01913.html

See Also: https://en.wikipedia.org/wiki/Bow_City_crater
 
Traces of a large impact crater have been discovered in Western Australia near Ora Banda. Although the headline says the impact occurred 100 million years ago its age is yet to be determined.
Gold miners discover 100 million-year-old meteorite crater Down Under

Gold miners in the Australian Outback recently discovered a gigantic meteorite crater dating to about 100 million years ago, back when dinosaurs roamed the Earth.

Found near the Western Australian town of Ora Banda, the newly dubbed Ora Banda Impact Crater is about 3 miles (5 kilometers) across. This huge hole was likely created by a meteorite up to 660 feet (200 meters) wide, or longer than the length of two American football fields, according to Resourc.ly, a Western Australia news outlet.

When geologists at Evolution Mining, an Australian gold mining company, came across some unusual rock cores at Ora Banda, they called Jayson Meyers, the principal geophysicist, director and founder of Resource Potentials, a geophysics consulting and contracting company in Perth. Meyers examined the geologists' drill core samples, as well as rock samples from the site, and he immediately noticed the shatter cones — telltale signs of a meteorite crash. ...

Because "we know they didn't do any nuclear testing at Ora Banda," the evidence suggests that an ancient impact crater hit the site, Meyers told Resourc.ly. ...

To learn more, Meyers examined the site's topography (that is, its varying elevations) and examined a gravity anomaly map, which shows how the gravity field at a particular site differs from a uniform, featureless Earth, according to NASA's Earth Observatory, which wasn't involved in the finding. ...

Meyer's work revealed a hidden impact crater with a pucker in the middle. This pucker is where shattered rocks came back to the surface after the comet struck, like a compressed spring that bounces back, Resourc.ly reported. When the geologists went to the "pucker" part of the site, they discovered shatter cones in the rocky outcrops. ...

Research on zircons and other minerals from the crater will likely reveal when the meteorite struck — right now, Meyers thinks it hit between 250 million and 40 million years ago. ...

FULL STORY: https://www.livescience.com/meteorite-crater-australia-outback.html
 
New Atlas of Impact Craters

The 600 page tome presents more than 200 collision sites on earth in high-resolution topographic maps and satellite images.

Titled ‘Terrestrial impact Structures’, the two-volumes include ‘essential details’ about each impact crater, including ones which have now vanished from view.

‘What we sum up in this atlas are all the confirmed impact structures, even the ones you don’t see.’

The researchers used a low orbit radar satellite dubbed TanDEM-X between 2010 and 2016 to measure every known crater on the Earth’s surface with a height accuracy of up to a metre.

Thought to have been 185 miles across and 25 miles deep, the world’s largest and oldest crater, the Vredefort, appeared when a meteorite or asteroid struck what is now South Africa some 2.02 billion years ago.

One example from Quebec:

Manicouagan - Quebec, Canada.
 
Earth's oldest known impact crater found in Greenland
A 100 kilometre-wide crater has been found in Greenland, the result of a massive asteroid or comet impact a billion years before any other known collision on Earth. ...
SOURCE: http://www.eurekalert.org/pub_releases/ ... 062812.php

Update ...

Subsequent and newly-published research indicates the Maniitsoq structure was formed by natural terrestrial processes and not an impact from the Archean bombardment.
Suspicions on True Origin of World's Oldest 'Impact Crater' Have Now Been Confirmed

Earth and giant meteorites go way back, but new research confirms that what had been proposed as the oldest impact crater on the planet – the 100-kilometer (62-mile) wide Maniitsoq structure – isn't actually an impact crater at all.

Through a combination of field mapping, rock dating, and geological chemical analysis techniques, researchers have been able to show that features previously argued to be the faint signature of a long-eroded crater were anything but. The alleged structure is as much the product of the same geological processes as those that created the surrounding region.

Estimated as being around 3 billion years old, the ricks within the Maniitsoq structure date from the Archean era (4-2.5 billion years ago), a period in Earth's history that geologists have little solid evidence to go on when it comes to impact craters.

"Our results conclusively rule out the proposal that much of the Archean rock mass in the Maniitsoq region formed by an Archean meteorite impact, which leaves the 2.23 Ga Yarrabubba structure in Western Australia as the oldest confirmed terrestrial impact structure," write the researchers in their published paper.

"The source craters for Archean-aged impact ejecta remain elusive on Earth." ...

FULL STORY: https://www.sciencealert.com/a-gian...rom-3-billion-years-ago-isn-t-what-we-thought
 
Here are the bibliographic details and abstract for the published report on the Maniitsoq structure analysis.

Chris Yakymchuk, Christopher L. Kirkland, Aaron J. Cavosie, Kristoffer Szilas, Julie Hollis, Nicholas J. Gardiner, Pedro Waterton, Agnete Steenfelt, Laure Martin,
Stirred not shaken; critical evaluation of a proposed Archean meteorite impact in West Greenland,
Earth and Planetary Science Letters
Volume 557, 2021,116730
ISSN 0012-821X
https://doi.org/10.1016/j.epsl.2020.116730.

Abstract
Large meteorite impacts have a profound effect on the Earth's geosphere, atmosphere, hydrosphere and biosphere. It is widely accepted that the early Earth was subject to intense bombardment from 4.5 to 3.8 Ga, yet evidence for subsequent bolide impacts during the Archean Eon (4.0 to 2.5 Ga) is sparse. However, understanding the timing and magnitude of these early events is important, as they may have triggered significant change points to global geochemical cycles. The Maniitsoq region of southern West Greenland has been proposed to record a ∼3.0 Ga meteorite impact, which, if confirmed, would be the oldest and only known impact structure to have survived from the Archean. Such an ancient structure would provide the first insight into the style, setting, and possible environmental effects of impact bombardment continuing into the late Archean. Here, using field mapping, geochronology, isotope geochemistry, and electron backscatter diffraction mapping of 5,587 zircon grains from the Maniitsoq region (rock and fluvial sediment samples), we test the hypothesis that the Maniitsoq structure represents Earth's earliest known impact structure. Our comprehensive survey shows that previously proposed impact-related geological features, ranging from microscopic structures at the mineral scale to macroscopic structures at the terrane scale, as well as the age and geochemistry of the rocks in the Maniitsoq region, can be explained through endogenic (non-impact) processes. Despite the higher impact flux, intact craters from the Archean Eon remain elusive on Earth.

SOURCE: https://www.sciencedirect.com/science/article/pii/S0012821X20306749
 
The new record for largest meteor crater created within the last 100,000 years has been attributed to a crater in China.
Scientists uncover the largest crater on Earth under 100,000 years old

A crescent-shaped crater in Northeast China holds the record as the largest impact crater on Earth that formed in the last 100,000 years.

Prior to 2020, the only other impact crater ever discovered in China was found in Xiuyan county of the coastal province of Liaoning, according to a statement from the NASA Earth Observatory. Then, in July 2021, scientists confirmed that a geological structure in the Lesser Xing'an mountain range had formed as a result of a space rock striking Earth. ...

The Yilan crater measures about 1.15 miles (1.85 kilometers) across and likely formed about 46,000 to 53,000 years ago, based on radiocarbon dating of charcoal and organic lake sediments from the site, the NASA statement says. Researchers collected these sediment samples by extracting a drillcore from the center of the crater ...

The so-called Meteor Crater in Arizona previously held the record for largest impact crater less than 100,000 years old; it's about 49,000 to 50,000 years old and measures 0.75 miles (1.2 km) in diameter. ...
FULL STORY: https://www.livescience.com/young-impact-crater-found-china
 
Impact crater found under glacier in Greenland ...

Newly announced research into this 19-mile-wide impact crater in Greenland - called the Hiawatha Crater - indicates it's much older than previously presumed.
Massive meteor crater discovered beneath Greenland's ice is much older than thought

The age of a 31-kilometer (19-mile) wide meteorite crater discovered under a kilometer of Greenland ice had long puzzled scientists.

The Hiawatha crater was exceptionally well preserved despite glacier ice being incredibly effective at erosion. Its state fueled talk that the meteorite might have hit as recently as 13,000 years ago.

However, the crater, which is one of the world's largest, has now been definitively dated -- and it is much, much older. In fact, it slammed into the Earth just a few million years after dinosaurs went extinct, about 58 million years ago. ...
FULL STORY: https://www.cnn.com/2022/03/09/world/crater-greenland-age-scn/index.html
 
If a big enough impactor strikes violently enough it can blow bits of the terrain (even down to the bedrock) upward and outward to form secondary impact craters. Such secondary craters are well-known on our moon.

For the first time scientists have identified a set of at least 30-some craters in southeastern Wyoming as secondary craters caused by a major impact event circa 280 million years ago.
This long-lost asteroid impact was so big its debris left more than 30 craters

Ricochet from a meteorite impact on Earth created a huge 'field' of craters that so far, we have only seen examples of on other planets.

The unique site in southeast Wyoming has more than 30 craters that were formed about 280 million years ago, researchers said in a new study. The craters were created after a meteorite impact hundreds of miles (or kilometers) away blew boulders of bedrock into the air.

"The trajectories indicate a single source and show that the craters were formed by ejected blocks from a large primary crater," study leader Thomas Kenkmann, a geologist at the University of Freiburg in Germany, said in a statement from the Geological Association of America, which published the new research. ...

"Secondary craters around larger craters are well known from other planets and moons," Kenkmann added, "but have never been found on Earth." Close to home, for example, lunar secondary craters pepper a region of the far side ...

In addition to 31 craters the scientists have firmly identified as secondary features, the team spotted more than 60 other contenders. ...
FULL STORY: https://www.livescience.com/long-lost-asteroid-impact-multiple-craters
 
Here are the bibliographic details and abstract for the published research report. The full report can be accessed at the link below.


Thomas Kenkmann, Louis Müller, Allan Fraser, Doug Cook, Kent Sundell, Auriol S.P. Rae
Secondary cratering on Earth: The Wyoming impact crater field.
GSA Bulletin 2022.
doi: https://doi.org/10.1130/B36196.1

A large number of small impact structures have been discovered in Wyoming, USA, and we raise the question of how this accumulation occurred. We document 31 crater structures of 10−70 m diameter with corresponding shock features but missing meteorite relics. All craters occur along the outcrops of the uppermost Permo-Pennsylvanian Casper Sandstone Formation and are ∼280 m.y. old. Their spatial arrangement shows clusters and ray-like alignments. Several craters have elliptical crater morphologies that allow the reconstruction of impact trajectories. The radial arrangement of the trajectories indicates that the craters are secondary craters formed by ejecta from a primary crater whose likely position and size are reconstructed. Modeling ballistic trajectories and secondary crater formation indicates that impacts occurred at around 700−1000 m/s and caused small shock volumes with respect to crater volumes. This is the first field of secondary craters found on Earth, and we disentangle its formation conditions.

SOURCE / FULL REPORT: https://pubs.geoscienceworld.org/gs...condary-cratering-on-Earth-The-Wyoming-impact
 
The largest terrestrial impact structure found to date is the 2 billion year old Vredefort structure / crater in South Africa. Newly published research indicates the impactor that created it was larger and faster than previously believed.
We Might Have Underestimated The Size of The Asteroid Behind Earth's Largest Crater

The Vredefort crater in South Africa is the largest of its kind on Earth, estimated to stretch as far as 300 kilometers (more than 180 miles) from rim to rim. Walking non-stop, it would take a good two-and-a-half days to make it from one side to the other.

The scars left by an asteroid collision some two billion years ago have long since been all but scoured away by the elements, leaving room for speculation over its true scale and the forces that created it. Now new research based on what's thought to be a more accurate simulation of the impact event suggests that the object that made the crater was larger than previously believed.

Earlier estimates put the asteroid at 15 kilometers (9.3 miles) in diameter, traveling at a velocity of 15 kilometers per second.

This latest analysis suggests the object responsible for the crater was closer to 20 to 25 kilometer across, traveling at a velocity of 15 to 20 kilometers per second in the moments before impact.

"Understanding the largest impact structure that we have on Earth is critical," says astrophysicist Natalie Allen, from Johns Hopkins University in Baltimore.

"Having access to the information provided by a structure like the Vredefort crater is a great opportunity to test our model and our understanding of the geologic evidence so we can better understand impacts on Earth and beyond." ...

If the new modeling is correct, the asteroid that hit two billion years ago would have been bigger than the one that created the Chicxulub crater and killed off the dinosaurs some 66 million years back in time. Most estimates put that crater at around 180 kilometers (112 miles) across.

"Unlike the Chicxulub impact, the Vredefort impact did not leave a record of mass extinction or forest fires, given that there were only single-cell lifeforms and no trees existed two billion years ago," says planetary scientist Miki Nakajima, from the University of Rochester in New York State.

"However, the impact would have affected the global climate potentially more extensively than the Chicxulub impact did." ...
FULL STORY: https://www.sciencealert.com/we-mig...-of-the-asteroid-behind-earths-largest-crater

PUBLISHED RESEARCH REPORT: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JE007186
 
The first impact crater on the Iberian Peninsula has been discovered in southern Spain.
Scientists Discover the First Impact Crater in Spain

The first probable impact crater in Spain has been discovered in the southern province of Almeria. The finding was recently reported by Juan Antonio Sánchez Garrido of the University of Almeria at the Europlanet Science Congress (EPSC) 2022.

Although there are over 200 impact structures known to exist, this study is the first to find evidence of an impact crater on the Iberian Peninsula. The finding is the product of 15 years of research conducted by an international team of scientists from the University of Almeria, the Astrobiology Center of Madrid, the University of Lund, and the University of Copenhagen. ...

Prof Sánchez Garrido said: “We believe that the impact event occurred around 8 million years ago. We have investigated numerous aspects of the geology, mineralogy, geochemistry, and geomorphology of the region. The basins of Alhabia and Tabernas in the area are filled with sediments dating back between 5 and 23 million years, and they overlie older metamorphic rocks. Much of the impact structure is buried by more modern sediments, but erosion has exposed it and opened up the opportunity for studies.”

The crater itself is estimated to be 4 kilometers (2.5 miles) in diameter, surrounded by a wider structure 20 kilometers (12.4 miles) across, where the impact caused the sedimentary strata to collapse. ...

Evidence for the impact crater includes several examples of ‘shocked’ quartz grains in breccia – a sedimentary rock type with large fragments cemented into a finer-grained matrix. The grains show signs of being deformed in the enormous pressures of the impact, which were between 10 and 30 gigapascals. ...
FULL STORY (With Illustrations): https://scitechdaily.com/scientists-discover-the-first-impact-crater-in-spain/
EPSC 2022 PRESENTATION:
“A probable impact structure in Betic Cordillera, Almeria, SE Spain”
Juan Antonio Sánchez Garrido, Jens Olof Ormö, Carl Alwmark, Sanna Alwmark, Gabriel Zachen, Robert Lilljequist and Sebastián Tomás Sánchez Gómez
23 September 2022, Europlanet Science Congress 2022.
https://doi.org/10.5194/epsc2022-217
 
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