scholarly journals Breakup of a long-period comet as the origin of the dinosaur extinction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Amir Siraj ◽  
Abraham Loeb
Keyword(s):  
Impact Crater ◽  
Main Belt ◽  
Long Period ◽  
Dinosaur Extinction ◽  
Chicxulub Impact Crater ◽  
Order Of Magnitude ◽  
Mass Extinction Event ◽  
Chicxulub Impact ◽  
The Impact ◽  
Impact Events

AbstractThe origin of the Chicxulub impactor, which is attributed as the cause of the K/T mass extinction event, is an unsolved puzzle. The background impact rates of main-belt asteroids and long-period comets have been previously dismissed as being too low to explain the Chicxulub impact event. Here, we show that a fraction of long-period comets are tidally disrupted after passing close to the Sun, each producing a collection of smaller fragments that cross the orbit of Earth. This population could increase the impact rate of long-period comets capable of producing Chicxulub impact events by an order of magnitude. This new rate would be consistent with the age of the Chicxulub impact crater, thereby providing a satisfactory explanation for the origin of the impactor. Our hypothesis explains the composition of the largest confirmed impact crater in Earth’s history as well as the largest one within the last million years. It predicts a larger proportion of impactors with carbonaceous chondritic compositions than would be expected from meteorite falls of main-belt asteroids.

Deccan Volcanism or the Chicxulub Impact: The Chicken or Egg Question

2020 ◽  
Author(s):  
Gerta Keller
Keyword(s):  
Mass Extinction ◽  
Impact Crater ◽  
Global Climate ◽  
Mass Extinctions ◽  
Deccan Volcanism ◽  
Asteroid Impact ◽  
Global Climate Warming ◽  
Chicxulub Impact Crater ◽  
Chicxulub Impact ◽  
The Impact

<p>The Cretaceous–Paleogene boundary (KTB or KPB) mass extinction is primarily known for the<br>demise of the dinosaurs, the Chicxulub impact, and the rancorous forty-year-old controversy<br>over the cause of this mass extinction. For the first 30 years, the controversy primarily revolved<br>around the age of the impact claimed as precisely KTB based on the assumption that it caused<br>the mass extinction. The iridium (Ir) anomaly at the KTB was claimed proof of the asteroid<br>impact, but no Ir was ever associated with impact evidence and recent findings reveal no<br>extraterrestrial component in PGEs or the KTB Ir anomaly. Impact melt rock glass spherules are<br>also claimed as indisputable evidence of the KTB age impact, but such spherule layers are<br>commonly reworked from the primary (oldest) layer in late Maastrichtian, KTB and Danian<br>sediments; thus only the oldest impact spherule layer documented near the base of zone CF1<br>~200 ky below the KTB can approximate the impact’s age. Similarly, the impact breccia in the<br>Chicxulub impact crater predates the KTB. The best age derived from Ar/Ar dating of impact<br>glass spherules is within 200 ky of the KTB and thus no evidence for the KTB age. All evidence<br>strongly suggests the Chicxulub impact most likely predates the mass extinction ~ 200 ky and<br>played no role in it.<br>Deccan volcanism (LIP) was dismissed as potential cause or even contributor to the KTB mass<br>extinction despite the fact that all other mass extinctions are associated with Large Igneous<br>Province (LIP) volcanism but none with an asteroid impact. During the last decade, Deccan<br>volcanism gained credence based on a succession of discoveries: 1) the mass extinction in<br>between the longest Deccan lava flows across India; 2) high-precision dating of the entire<br>sequence of Deccan volcanism based on UPb zircon dating; 3) recognition of four distinct<br>eruption pulses all related to global climate warming with the largest pulse beginning 20 ky prior<br>to and ending at the KTB; 4) Identifying the climate link to Deccan volcanism based on age<br>dating and mercury from Deccan eruptions in marine sediments; and 5) Identifying the KTB<br>mass extinction directly related to the major Deccan eruption pulse, hyperthermal warming and<br>ocean acidification all linked to global mercury fallout from Deccan eruptions in marine<br>sediments. Despite this remarkable culmination of evidence, the controversy continues with<br>impact proponents arguing that Deccan volcanism didn’t exist at the KTB – the impact was the<br>sole cause.</p>

POST IMPACT RECOVERY OF THE DEEP GRANITIC BIOSPHERE OF THE CHICXULUB IMPACT CRATER

2021 ◽  
Author(s):  
S.N. Quraish ◽  
K. Grice ◽  
C. Cockell ◽  
A. Holman ◽  
P. Hopper ◽  
...  
Keyword(s):  
Impact Crater ◽  
Chicxulub Impact Crater ◽  
Post Impact ◽  
Chicxulub Impact

Borehole magnetic surveys in weakly magnetic sediments (Chicxulub impact crater) versus strongly magnetic volcanics (Bathurst mining camp)

2019 ◽  
Vol 56 (5) ◽  
pp. 504-524
Author(s):  
William A. Morris ◽  
Sara-Lise Underhay ◽  
Hernan Ugalde ◽  
Bernd Milkereit
Keyword(s):  
Magnetic Property ◽  
Impact Crater ◽  
Magnetic Data ◽  
Coordinate Space ◽  
Systematic Change ◽  
Fluxgate Magnetometer ◽  
Magnetic Vector ◽  
Chicxulub Impact Crater ◽  
Bathurst Mining Camp ◽  
Chicxulub Impact

Borehole navigation surveys performed using a triaxial fluxgate magnetometer record the change in orientation of the magnetic vector versus depth. Variations in the orientation of the magnetic vector arise from either on- or off-hole magnetic sources. On-hole magnetic sources associated with magnetic property fluctuations in the immediate wall of the borehole (i.e., susceptibility) and (or) remanence polarity changes produce sharp-edged anomalies. Off-hole magnetic sources, caused by a magnetic body near, but not penetrated by, the borehole, produce broad smooth anomalies. Prior to the interpretation of borehole magnetic anomaly logs, data corrections must be applied. Data from each of the magnetic and tiltmeter sensors must be corrected for differential gain, base value offset, and nonorthogonality. By using a probe with two sets of triaxial fluxgates, it is possible to detect along hole magnetic field rotations, which compromise the borehole navigation calculations. After rotation into geographic coordinate space, borehole vector magnetic data from the Chicxulub impact crater in Mexico showed no evidence for any systematic change of magnetic property versus depth. What was originally interpreted as reversal stratigraphy has proved to be minor changes in borehole geometry. Borehole magnetic data from a borehole through the Stratmat deposit, located in the Bathurst mining camp, New Brunswick, show strong off-hole and on-hole anomalies associated with the pyrrhotite-rich ore bodies.

Palaeocene–Eocene miospores from the Chicxulub impact crater, Mexico. Part 1: spores and gymnosperm pollen

Palynology ◽  
2019 ◽  
Vol 44 (3) ◽  
pp. 473-487 ◽  
Author(s):  
Vann Smith ◽  
Sophie Warny ◽  
David M. Jarzen ◽  
Thomas Demchuk ◽  
Vivi Vajda ◽  
...  
Keyword(s):  
Impact Crater ◽  
Chicxulub Impact Crater ◽  
Chicxulub Impact

scholarly journals Probing the hydrothermal system of the Chicxulub impact crater

2020 ◽  
Vol 6 (22) ◽  
pp. eaaz3053 ◽  
Author(s):  
David A. Kring ◽  
Sonia M. Tikoo ◽  
Martin Schmieder ◽  
Ulrich Riller ◽  
Mario Rebolledo-Vieyra ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Earth’S Crust ◽  
Scientific Drilling ◽  
Chicxulub Impact Crater ◽  
Earth's Crust ◽  
International Ocean Discovery Program ◽  
Geomagnetic Polarity ◽  
Chicxulub Impact ◽  
The Impact ◽  
Yellowstone Caldera

The ~180-km-diameter Chicxulub peak-ring crater and ~240-km multiring basin, produced by the impact that terminated the Cretaceous, is the largest remaining intact impact basin on Earth. International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition 364 drilled to a depth of 1335 m below the sea floor into the peak ring, providing a unique opportunity to study the thermal and chemical modification of Earth’s crust caused by the impact. The recovered core shows the crater hosted a spatially extensive hydrothermal system that chemically and mineralogically modified ~1.4 × 105 km3 of Earth’s crust, a volume more than nine times that of the Yellowstone Caldera system. Initially, high temperatures of 300° to 400°C and an independent geomagnetic polarity clock indicate the hydrothermal system was long lived, in excess of 106 years.

scholarly journals Geochemistry, geochronology and petrogenesis of Maya Block granitoids and dykes from the Chicxulub Impact Crater, Gulf of México: Implications for the assembly of Pangea

2020 ◽  
Vol 82 ◽  
pp. 128-150 ◽  
Author(s):  
Jiawei Zhao ◽  
Long Xiao ◽  
Sean P.S. Gulick ◽  
Joanna V. Morgan ◽  
David Kring ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Impact Crater ◽  
Chicxulub Impact Crater ◽  
Chicxulub Impact

Importance of pre-impact crustal structure for the asymmetry of the Chicxulub impact crater

2008 ◽  
Vol 1 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Sean P. S. Gulick ◽  
Penny J. Barton ◽  
Gail L. Christeson ◽  
Joanna V. Morgan ◽  
Matthew McDonald ◽  
...  
Keyword(s):  
Crustal Structure ◽  
Impact Crater ◽  
Chicxulub Impact Crater ◽  
The Asymmetry ◽  
Chicxulub Impact
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