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It appears that this March 2019 report on supporting evidence from Chile hadn't been noted here before ...
Geologic evidence supports theory that major cosmic impact event occurred approximately 12,800 years ago

When UC Santa Barbara geology professor emeritus James Kennett and colleagues set out years ago to examine signs of a major cosmic impact that occurred toward the end of the Pleistocene epoch, little did they know just how far-reaching the projected climatic effect would be.

"It's much more extreme than I ever thought when I started this work," Kennett noted. ...

He's talking about the Younger Dryas Impact Hypothesis, which postulates that a fragmented comet slammed into the Earth close to 12,800 years ago, causing rapid climatic changes, megafaunal extinctions, sudden human population decrease and cultural shifts and widespread wildfires (biomass burning). ...

Now, in a paper published in the journal Nature Scientific Reports, Kennett and colleagues, led by Chilean paleontologist Mario Pino, present further evidence of a cosmic impact, this time far south of the equator, that likely lead to biomass burning, climate change and megafaunal extinctions nearly 13,000 years ago.

"We have identified the YDB layer at high latitudes in the Southern Hemisphere at near 41 degrees south, close to the tip of South America," Kennett said. This is a major expansion of the extent of the YDB event." The vast majority of evidence to date, he added, has been found in the Northern Hemisphere. ...
FULL STORY: https://phys.org/news/2019-03-geologic-evidence-theory-major-cosmic.html
 
Here's the published report from the Chilean study ...

Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka
Abstract
The Younger Dryas (YD) impact hypothesis posits that fragments of a large, disintegrating asteroid/comet struck North America, South America, Europe, and western Asia ~12,800 years ago. Multiple airbursts/impacts produced the YD boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at >50 sites across ~50 million km² of Earth’s surface. This proposed event triggered extensive biomass burning, brief impact winter, YD climate change, and contributed to extinctions of late Pleistocene megafauna. In the most extensive investigation south of the equator, we report on a ~12,800-year-old sequence at Pilauco, Chile (~40°S), that exhibits peak YD boundary concentrations of platinum, gold, high-temperature iron- and chromium-rich spherules, and native iron particles rarely found in nature. A major peak in charcoal abundance marks an intense biomass-burning episode, synchronous with dramatic changes in vegetation, including a high-disturbance regime, seasonality in precipitation, and warmer conditions. This is anti-phased with northern-hemispheric cooling at the YD onset, whose rapidity suggests atmospheric linkage. The sudden disappearance of megafaunal remains and dung fungi in the YDB layer at Pilauco correlates with megafaunal extinctions across the Americas. The Pilauco record appears consistent with YDB impact evidence found at sites on four continents. ...
FULL STORY: https://www.nature.com/articles/s41598-018-38089-y
 
... And now the explanatory pendulum begins to swing the other way - i.e., in the direction of something other than a catastrophic impact from outer space.

New evidence indicates the levels of rare earth elements disseminated were too low to reflect an impact, these lower levels could be attributed to volcanic activity, and spikes in the elements' distribution occurred multiple times rather than just once.

Cave sediments suggest global cooling 13K years ago not caused by asteroid

Geochemical signatures found in sediments recovered from a Texas cave suggest the Younger Dryas, a period of global cooling that occurred 13,000 years ago, was caused by a series of Earth-based processes, not an extraterrestrial impact.

Previously, scientists in search of an explanation for the Younger Dryas have pointed to spikes in several rare earth metals as evidence that an asteroid or comet impact triggered the cooling. ...

Most recently, when researchers looked at the sedimentary evidence, they found these spikes in rare earth metals actually featured relatively low concentrations of iridium, ruthenium, platinum, palladium and rhenium -- levels inconsistent with an extraterrestrial impact event.

"The isotopic signatures and concentrations can be explained by processes of volcanic eruption, condensation and transport of aerosols, which enriched the concentration and shifted the isotopic composition," Steven Forman, professor of geosciences at Baylor University, told UPI. ...

In addition to finding relatively low levels of the rare earth metals, researchers also found the same geochemical signature occurred several times in sediments dated between 9,000 and 15,000 years ago.

"The supposed 'comet' signature did not just occur during the Young Dryas but at four other age-levels, which is physically impossible," Forman said. "This is one piece of evidence that it was not a comet, but an aerosol signature in the atmosphere from a distant volcanic eruption."

While the new research, published Friday in the journal Scientific Advances, undermines an extraterrestrial explanation for the Younger Dryas, the study doesn't offer its own definitive trigger for the 1,200-year period of global cooling. ...

FULL STORY: https://www.upi.com/Science_News/20...ars-ago-not-caused-by-asteroid/4761596221876/
 
Here are the bibliographic details and abstract of the latest published study. The full report can be accessed at the link below.

Volcanic origin for Younger Dryas geochemical anomalies ca. 12,900 cal B.P.
N. Sun, A. D. Brandon, S. L. Forman, M. R. Waters and K. S. Befus
Science Advances 31 Jul 2020:
Vol. 6, no. 31, eaax8587
DOI: 10.1126/sciadv.aax8587
Abstract
The Younger Dryas (YD) abrupt cooling event ca. 12.9 ± 0.1 ka is associated with substantial meltwater input into the North Atlantic Ocean, reversing deglacial warming. One controversial and prevailing hypothesis is that a bolide impact or airburst is responsible for these environmental changes. Here, highly siderophile element (HSE; Os, Ir, Ru, Pt, Pd, and Re) abundances and 187Os/188Os ratios were obtained in a well-dated sediment section at Hall’s Cave, TX, USA to test this hypothesis. In Hall’s Cave, layers below, above, and in the YD have 187Os/188Os ratios consistent with incorporation of extraterrestrial or mantle-derived material. The HSE abundances indicate that these layers contain volcanic gas aerosols and not extraterrestrial materials. The most likely explanation is that episodic, distant volcanic emissions were deposited in Hall’s Cave sediments. Coupled 187Os/188Os ratios and HSE concentration data at close stratigraphic intervals are required to effectively differentiate between bolide and volcanic origins.

SOURCE: https://advances.sciencemag.org/content/6/31/eaax8587
 
Comet strike may have sparked key shift in human civilization

heritagedaily.com
24 June, 2021

A cluster of comet fragments believed to have hit Earth nearly 13,000 years ago may have shaped the origins of human civilisation, research suggests.

Possibly the most devastating cosmic impact since the extinction of the dinosaurs, it appears to coincide with major shifts in how human societies organised themselves, researchers say.

Their analysis backs up claims that an impact occurred prior to start of the Neolithic period in the so-called Fertile Crescent of southwest Asia.

During that time, humans in the region – which spans parts of modern-day countries such as Egypt, Iraq and Lebanon – switched from hunter-gatherer lifestyles to ones centred on agriculture and the creation of permanent settlements.

It is thought that the comet strike – known as the Younger Dryas impact – also wiped out many large animal species and ushered in a mini ice age that lasted more than 1,000 years.

Since it was proposed in 2007, the theory about the catastrophic comet strike has been the subject of heated debate and much academic research. Now, researchers from the University of Edinburgh have reviewed evidence assessing the likelihood that an impact took place, and how the event may have unfolded.

The team says a large body of evidence supports the theory that a comet struck around 13,000 years ago. Researchers analysed geological data from four continents, particularly North America and Greenland, where the largest fragments are thought to have struck.

Their analysis highlights excess levels of platinum, signs of materials melted at extremely high temperatures and the detection of nanodiamonds known to exist inside comets and form during high-energy explosions. All of this evidence strongly supports the impact theory, researchers say.

(...)

https://www.heritagedaily.com/2021/...ed-key-shift-in-human-civilization/139564?amp

This is the published paper:

https://www.research.ed.ac.uk/en/pu...pact-hypothesis-review-of-the-impact-evidence
 
Does the author mean meteor rather than comet? comets are ice i thought
No - the author means comet ... Comets typically contain ice (both water ice and frozen gases), but they also contain dust and rocks as well.
 
Newly published research indicates glass fields in the Atacama Desert (Chile) support the extraterrestrial impact hypothesis. However the estimated time of these shards' origin is almost a millennium later that most estimates of the Younger Dryas whatever-it-was event.
Mysterious Shards of Glass Are Strewn Across Miles of Desert, And We Finally Know Why

They first came to scientists' attention about a decade ago: A mysterious field of glass fragments, scattered across Chile's Atacama Desert, and aligned in a vast corridor stretching 75 kilometers long (almost 50 miles).

These strange pieces of glass, too many to be counted, are clustered in a number of sites along the desert corridor, and they take a number of shapes, some occurring in large slabs up to 50 centimeters (20 inches) across.

They have both rough and smooth features, and look as if they've been somehow folded and twisted into their current forms, scientists say. ...

Whatever it was that triggered these violent, messy transformations roughly 12,000 years ago has never been fully understood. ...

An early hypothesis suggested they could be the result of a large meteor exploding in the atmosphere – a giant airburst throwing fragments of hot, fiery space rock onto the desert surface, with the extra-terrestrial shrapnel melting the sand and soil on the spot. ...

Mysterious glass remnants like this have been found in numerous locations across the planet, and in many cases, meteoric explosions or impacts are taken as the most likely explanations for how the glass got there. ...

In the case of Atacama's glass shards, scientists have also suggested they could have formed in the furnace of natural surface fires, in a different age and climate when the desert was covered in more abundant vegetation. ...

In the new study, the researchers collected and studied over 300 samples of the desert glass, examining them under an electron microscope, and analyzing their chemical composition through spectroscopy.

The results, the team says, unequivocally suggest the glass is not wholly of this planet. ...

Another coincidence that bears further investigation is that the timing of this airburst broadly overlaps with the disappearance of Quaternary megafauna in South America, which itself coincided with both the arrival of ancient hunter-gatherers in the area, and changes in climate as well. ...
FULL STORY: https://www.sciencealert.com/myster...cross-miles-of-desert-and-we-finally-know-why
 
Here are the bibliographic details and abstract from the published research report. The full paper is accessible (as a PDF download) at the link below.


Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile
Peter H. Schultz; R. Scott Harris; Sebastián Perroud; Nicolas Blanco; Andrew J. Tomlinson
Geology (2021)
https://doi.org/10.1130/G49426.1

Twisted and folded silicate glasses (up to 50 cm across) concentrated in certain areas across the Atacama Desert near Pica (northern Chile) indicate nearly simultaneous (seconds to minutes) intense airbursts close to Earth’s surface near the end of the Pleistocene. The evidence includes mineral decompositions that require ultrahigh temperatures, dynamic modes of emplacement for the glasses, and entrained meteoritic dust. Thousands of identical meteoritic grains trapped in these glasses show compositions and assemblages that resemble those found exclusively in comets and CI group primitive chondrites. Combined with the broad distribution of the glasses, the Pica glasses provide the first clear evidence for a cometary body (or bodies) exploding at a low altitude. This occurred soon after the arrival of proto-Archaic hunter-gatherers and around the time of rapid climate change in the Southern Hemisphere.

SOURCE: https://pubs.geoscienceworld.org/gs...pread-glasses-generated-by-cometary-fireballs
 
Oh, the Middle East and Chile?
More than one impact?
It would seem so ... It also seems to involve more than one timeframe, too.

The alleged Chilean impact evidence was dated to something like 800 - 900 years later than the estimated time for the North American and other impact events.
 
Same comet perhaps, breaking up and leaving debris in place for a later encounter? Similar to the way the annual Orionids are meant to be linked to Halley's comet? Probably never know as I guess the impact timings won't be exact enough to work out orbits.
Isn't this similar to Graham Hancock's theories?
Thought I read somewhere about strings of craters in South America thought to be caused by "glancing" impacts, but can't find anything on a very quick search - perhaps I imagined it?
 
Thought I read somewhere about strings of craters in South America thought to be caused by "glancing" impacts, but can't find anything on a very quick search - perhaps I imagined it?
I believe you're referring to the Rio Cuarto craters in Argentina:

https://en.wikipedia.org/wiki/Río_Cuarto_craters

Initial studies of these structures found evidence of meteoritic material, resulting in a first guess they represented very low angular impacts. More recent studies have identified a few hundred similar structures in the area which are arguably the result of wind effects. As a result, it's been suggested the various structures and material evidence may have resulted from two separate events and causes.
 
I believe you're referring to the Rio Cuarto craters in Argentina:

https://en.wikipedia.org/wiki/Río_Cuarto_craters

Initial studies of these structures found evidence of meteoritic material, resulting in a first guess they represented very low angular impacts. More recent studies have identified a few hundred similar structures in the area which are arguably the result of wind effects. As a result, it's been suggested the various structures and material evidence may have resulted from two separate events and causes.
That's it. Thanks
 
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