Team says it’s found pieces of the asteroid that killed off the dinosaurs

Jan 27, 2020
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Science

But experts want to see more data

8 APR. 2022
BY MICHAEL PRICE

A fossil-rich site known as Tanis in North Dakota has preserved tiny shards of the asteroid that wiped out the dinosaurs, The New York Times reports. At a talk this week at NASA’s Goddard Space Flight Center, paleontologist Robert DePalma argued that his group had found pieces of amber in sedimentary layers thought to date to the exact moment of the impact. Inside the amber were bits of rock that bear the mineralogical signature of an asteroid—not a comet, as others have suggested. He also presented evidence for the first fossilized embryo of a flying reptile called a pterosaur. DePalma's team showed off the fossils in a new BBC documentary as well. But because the work has yet to undergo peer review other researchers say they’re waiting to see the evidence for themselves before they accept the results.

See: https://www.science.org/content/article/team-says-it-s-found-pieces-asteroid-killed-dinosaurs?utm_source=sfmc&utm_medium=email&utm_campaign=DailyLatestNews&utm_content=alert&et_rid=255259432&et_cid=4192960

I was also interested in viewing the original paper:

A seismically induced onshore surge deposit at the KPg boundary, North Dakota

by
Robert A. DePalmaa,b,c,1, Jan Smitd, David A. Burnhama,e,1, Klaudia Kuiperd, Phillip L. Manning, f, Anton Oleinikc, Peter Larsong, Florentin J. Maurrasseh, Johan Vellekoopi,j, Mark A. Richardsk,l, Loren Gurcheb, and Walter Alvarez,k

aDepartment of Geology, University of Kansas, Lawrence, KS 66045; bDepartment of Vertebrate Paleontology, The Palm Beach Museum of Natural History, Fort Lauderdale, FL 33306; cDepartment of Geosciences, Florida Atlantic University, Boca Raton, FL 33431; dDepartment of Geology and Geochemistry, Faculty of Science, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands; eBiodiversity Institute, University of Kansas, Lawrence, KS 66045; fSchool of Earth & Environmental Sciences, University of Manchester, Manchester M13 9PL, United Kingdom; gBlack Hills Institute of Geological Research, Hill City, SD 57745; hDepartment of Earth and Environment, Florida International University, Miami, FL 33199; iDepartment of Earth and Environmental Sciences, Catholic University of Leuven, 3001 Leuven, Belgium; jAnalytical, Environmental, and Geo- Chemistry, Vrije Universiteit Brussel, B-1050 Brussels, Belgium; kDepartment of Earth and Planetary Science, University of California, Berkeley, CA 94720; and lDepartment of Earth and Space Sciences, University of Washington, Seattle, WA 98195

The most immediate effects of the terminal-Cretaceous Chicxulub impact, essential to understanding the global-scale environmental and biotic collapses that mark the Cretaceous–Paleogene extinction, are poorly resolved despite extensive previous work. Here, we help to resolve this by describing a rapidly emplaced, high- energy onshore surge deposit from the terrestrial Hell Creek Formation in Montana. Associated ejecta and a cap of iridium-rich impactite reveal that its emplacement coincided with the Chicxulub event. Acipenseriform fish, densely packed in the deposit, contain ejecta spherules in their gills and were buried by an inland-directed surge that inundated a deeply incised river channel before accretion of the fine-grained impactite. Although this deposit displays all of the physical characteristics of a tsunami runup, the timing (<1 hour postimpact) is instead consistent with the arrival of strong seismic waves from the magnitude Mw ∼10 to 11 earthquake generated by the Chicxulub impact, identifying a seismically coupled seiche inundation as the likely cause.

Our findings present high-resolution chronology of the immediate aftereffects of the Chicxulub impact event in the Western Interior, and report an impact-triggered on- shore mix of marine and terrestrial sedimentation—potentially a significant advancement for eventually resolving both the complex dynamics of debris ejection and the full nature and extent of biotic disruptions that took place in the first moments postimpact.

Screen Shot 2022-04-14 at 7.51.04 PM.png
Map of the Tanis study locality. (A) Tanis within a regional context (large map) and on a national map (Inset). Reprinted with permission from ref. 14; black dots in Inset are previously documented KPg tsunami localities; star denotes Tanis. Kf, Fox Hills Formation; Kh, Hell Creek Formation; Kp, Pierre Shale; Qor, Holocene; QTu, Quaternary and Upper Tertiary; Tp, Slope Formation. (B) Photo and interpretive overlay of an oblique cross-section through Tanis, showing the contact between the angled point-bar sandstone and the gray Hell Creek bedrock. (C) Simplified schematic depicting the general contemporaneous depositional setting for the Event Deposit (not to scale). The Event Deposit (1) covers the slope of a prograding point bar of a meander (2), which incised into the Hell Creek bedrock during the late Cretaceous. Location of the densest carcass accumulations (3) along the slope; location of KPg boundary tonstein directly overlying the Event Deposit (4); location of KPg tonstein overlying the adjacent overbank (5); location of Brooke Butte (6), the closest KPg outcrop to Tanis.


Screen Shot 2022-04-14 at 8.09.11 PM.png
Chicxulub tonstein capping the Event Deposit at Tanis and representative impact-derived materials. (A) Iridium-enriched tonstein in situ atop the Event Deposit. (B) Shocked mineral with multiple intersecting planar deformation features (FAU.DGS.ND.161.977.T). (C) Clay-altered ejecta spherules (FAU.DGS.ND.161.33.T), some with prominent schlieren. (D) Micro-CT of a clay-altered ejecta spherule with unaltered glass core (FAU.DGS.ND.161.11.T). (E) Shards of unaltered impact glass (FAU.DGS.ND.161.45.T).

Even more remarkable are spherules concentrated in the gill rakers of more than 50% of acipenseriform (sturgeon and paddlefish) fish carcasses within the deposit. Passive suspension feeding is a common specialization among some acipenseriforms (i.e., certain paddlefish taxa), which sieve food with their gills while swimming open- mouthed. It is most likely that the Tanis paddlefish inadvertently aspirated the spherules by this mechanism when the ejecta settled through the water column. Spherules within the fish carcasses at Tanis suggest that the impact event and associated macrofossils were temporally correlated.

See: https://www.researchgate.net/publication/332150842

Again, while other scientists will delve into these findings, I find the possibility that shards from the Chicxulub blast have been possibly identified and were caught in the gills of certain fish while swimming open mouthed before becoming entombed in the aftermath of the most asteroid strike on Earth - the one which helped shuffle the dinosaurs into extinction. I urge those interested in KPg boundary to read the entire article in researchgate.net.
Hartmann352
 

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