Chicxulub crater

The Chicxulub crater (/ˈtʃiːkʃʊluːb/; Mayan: [tʃʼikʃuluɓ]) is an impact crater buried underneath the Yucatán Peninsula in Mexico.[4] Its center is located near the town of Chicxulub, after which the crater is named.[5] It was formed by a large asteroid or comet about 11 to 81 kilometres (6.8 to 50.3 miles) in diameter,[2] the Chicxulub impactor, striking the Earth. The date of the impact coincides precisely with the Cretaceous–Paleogene boundary (K–Pg boundary), slightly less than 66 million years ago,[3] and a widely accepted theory is that worldwide climate disruption from the event was the cause of the Cretaceous–Paleogene extinction event, a mass extinction in which 75% of plant and animal species on Earth became extinct, including all non-avian dinosaurs.

The crater is estimated to be 150 kilometres (93 miles) in diameter[4] and 20 km (12 mi) in depth, well into the continental crust of the region of about 10–30 km (6.2–18.6 mi) depth. It is the second largest confirmed impact structure on Earth and the only one whose peak ring is intact and directly accessible for scientific research.[6]

The crater was discovered by Antonio Camargo and Glen Penfield, geophysicists who had been looking for petroleum in the Yucatán during the late 1970s. Penfield was initially unable to obtain evidence that the geological feature was a crater and gave up his search. Later, through contact with Alan Hildebrand in 1990, Penfield obtained samples that suggested it was an impact feature. Evidence for the impact origin of the crater includes shocked quartz,[7] a gravity anomaly, and tektites in surrounding areas.

In 2016, a scientific drilling project drilled deep into the peak ring of the impact crater, hundreds of meters below the current sea floor, to obtain rock core samples from the impact itself. The discoveries were widely seen as confirming current theories related to both the crater impact and its effects.[8]

Chicxulub crater
Chicxulub impact structure
Yucatan chix crater
Imaging from NASA's Shuttle Radar Topography Mission STS-99 reveals part of the 180 km (110 mi) diameter ring of the crater. The numerous sinkholes clustered around the trough of the crater suggest a prehistoric oceanic basin in the depression left by the impact.[1]
Impact crater/structure
Diameter150 km (93 mi)
Depth20 km (12 mi)
Impactor diameter11–81 kilometres (6.8–50.3 mi)[2]
Age66.043 ± 0.011 Ma
Cretaceous–Paleogene boundary[3]
Bolide typeCarbonaceous chondrite
Coordinates21°24′0″N 89°31′0″W / 21.40000°N 89.51667°WCoordinates: 21°24′0″N 89°31′0″W / 21.40000°N 89.51667°W
Country Mexico
Chicxulub crater is located in North America
Chicxulub crater
Chicxulub crater
Location of Chicxulub crater
Chicxulub crater is located in Mexico
Chicxulub crater
Chicxulub crater
Chicxulub crater (Mexico)


Gravity anomaly map of the Chicxulub impact area. The coastline is shown as a white line. A series of concentric features reveals the location of the crater. White dots represent cenotes (water-filled sinkholes). A ring of cenotes is associated with the largest semicircular feature, although its exact origin remains unclear.

In 1978, geophysicists Glen Penfield and Antonio Camargo were working for the Mexican state-owned oil company Petróleos Mexicanos, or Pemex, as part of an airborne magnetic survey of the Gulf of Mexico north of the Yucatán peninsula.[9] Penfield's job was to use geophysical data to scout possible locations for oil drilling.[10] In the data, Penfield found a huge underwater arc with "extraordinary symmetry" in a ring 70 km (40 mi) across.[5] He then obtained a gravity map of the Yucatán made in the 1960s.

A decade earlier, the same map suggested an impact feature to contractor Robert Baltosser, but he was forbidden to publicize his conclusion by Pemex corporate policy of the time.[11] Penfield found another arc on the peninsula itself, the ends of which pointed northward. Comparing the two maps, he found the separate arcs formed a circle, 180 km (110 mi) wide, centered near the Yucatán village Chicxulub; he felt certain the shape had been created by a cataclysmic event in geologic history.[10]

Chicxulub shockedquartz
Penfield with the sample of shocked quartz found at Well #2, Chicxulub

Pemex disallowed release of specific data but let Penfield and company official Antonio Camargo present their results at the 1981 Society of Exploration Geophysicists conference.[12] That year's conference was underattended and their report attracted scant attention. Coincidentally, many experts in impact craters and the K–Pg (Cretaceous–Paleogene) boundary were attending a separate conference on Earth impacts. Although Penfield had plenty of geophysical data sets, he had no rock cores or other physical evidence of an impact.[10]

He knew Pemex had drilled exploratory wells in the region. In 1951, one bored into what was described as a thick layer of andesite about 1.3 kilometres (4,300 ft) down. This layer could have resulted from the intense heat and pressure of an Earth impact, but at the time of the borings it was dismissed as a lava dome—a feature uncharacteristic of the region's geology. Penfield tried to secure site samples, but was told such samples had been lost or destroyed.[10] When attempts at returning to the drill sites and looking for rocks proved fruitless, Penfield abandoned his search, published his findings and returned to his Pemex work.

At the same time, in 1980, geologist Walter Alvarez and his father, Nobel Prize-winning scientist Luis Walter Alvarez, put forth his hypothesis that a large extraterrestrial body had struck Earth. In 1981, unaware of Penfield's discovery, University of Arizona graduate student Alan R. Hildebrand and faculty adviser William V. Boynton published a draft Earth-impact theory and sought a candidate crater.[13] Their evidence included greenish-brown clay with surplus iridium containing shocked quartz grains and small weathered glass beads that looked to be tektites.[14] Thick, jumbled deposits of coarse rock fragments were also present, thought to have been scoured from one place and deposited elsewhere by a megatsunami resulting from an Earth impact.[15] Such deposits occur in many locations but seem concentrated in the Caribbean basin at the K–Pg boundary.[15] So when Haitian professor Florentine Morás discovered what he thought to be evidence of an ancient volcano on Haiti, Hildebrand suggested it could be a telltale feature of a nearby impact.[16] Tests on samples retrieved from the K–Pg boundary revealed more tektite glass, formed only in the heat of asteroid impacts and high-yield nuclear detonations.[16]

In 1990, Houston Chronicle reporter Carlos Byars told Hildebrand of Penfield's earlier discovery of a possible impact crater.[17] Hildebrand contacted Penfield in April 1990 and the pair soon secured two drill samples from the Pemex wells, stored in New Orleans.[18] Hildebrand's team tested the samples, which clearly showed shock-metamorphic materials.

A team of California researchers including Kevin Pope, Adriana Ocampo, and Charles Duller, surveying regional satellite images in 1996, found a cenote (sinkhole) ring centered on Chicxulub that matched the one Penfield saw earlier; the cenotes were thought to be caused by subsidence of bolide-weakened lithostratigraphy around the impact crater wall.[19] More recent evidence suggests the actual crater is 300 km (190 mi) wide, and the 180 km ring is in fact an inner wall of it.[20]

Impact specifics

Researchers at the University of Glasgow dated tektite samples from the impact as 66,038,000 ± 11,000 years old.[21]

The Chicxulub impactor had an estimated diameter of 11–81 kilometres (6.8–50.3 mi), and delivered an estimated energy of 21–921 billion Hiroshima A-bombs (between and joules, or 1.3–58 yottajoules).[2] For comparison, this is ~100 million times the energy released by the Tsar Bomba, a thermonuclear device ("H-bomb") that remains the most powerful man-made explosive ever detonated, which released 210 petajoules ( joules, or 50 megatons TNT).[22] The impact created a hole 100 kilometres (62 mi) wide and 30 kilometres (19 mi) deep, leaving a crater mainly under the sea and covered by 600 metres (2,000 ft) of sediment by the 21st century.[23]


An animation showing the impact, and subsequent crater formation (University of Arizona, Space Imagery Center)

The impact would have caused a megatsunami over 100 metres (330 ft) tall[24] that would have reached all the way to what are now Texas and Florida.[25] The height of the tsunami was limited by the relatively shallow sea in the area of the impact; in deep ocean it would have been 4.6 kilometres (2.9 mi) tall.[24] A cloud of super-heated dust, ash and steam would have spread from the crater as the impactor burrowed underground in less than a second.[26] Excavated material along with pieces of the impactor, ejected out of the atmosphere by the blast, would have been heated to incandescence upon re-entry, broiling the Earth's surface and possibly igniting wildfires; meanwhile, colossal shock waves would have triggered global earthquakes and volcanic eruptions.[27] Fossil evidence for an instantaneous die-off of diverse animals was found in a soil layer only 10 centimetres (3.9 in) thick in New Jersey some 5,000 kilometres (3,100 mi) away from the impact site, indicating that death and burial under debris occurred suddenly and quickly over wide distances on land.[23] Field research from the Hell Creek Formation in North Dakota published in 2019[28] shows the simultaneous mass extinction of myriad species combined with geological and atmospheric features consistent with the impact event.

The emission of dust and particles could have covered the entire surface of the Earth for several years, possibly a decade, creating a harsh environment for living things. The shock production of carbon dioxide caused by the destruction of carbonate rocks would have led to a sudden greenhouse effect.[29] Over a decade or longer, sunlight would have been blocked from reaching the surface of the Earth by the dust particles in the atmosphere, cooling the surface dramatically. Photosynthesis by plants would also have been interrupted, affecting the entire food chain.[30][31] A model of the event developed by Lomax et al. (2001) suggests that net primary productivity (NPP) rates may have increased to higher than pre-impact levels over the long term because of the high carbon dioxide concentrations.[32]

In February 2008, a team of researchers led by Sean Gulick at the University of Texas at Austin's Jackson School of Geosciences used seismic images of the crater to determine that the impactor landed in deeper water than was previously assumed. They argued that this would have resulted in increased sulfate aerosols in the atmosphere. According to the press release, that "could have made the impact deadlier in two ways: by altering climate (sulfate aerosols in the upper atmosphere can have a cooling effect) and by generating acid rain (water vapor can help to flush the lower atmosphere of sulfate aerosols, causing acid rain)."[33] This was borne out by the results of a drilling project in 2016 which found that sulfate-containing rocks found in the area were not found in the peak ring (the rocks found were from deep within the earth's crust instead), the interpretation being that they had been vaporized by the impact and dispersed into the atmosphere.

A long-term local effect of the impact was the creation of the Yucatán sedimentary basin which "ultimately produced favorable conditions for human settlement in a region where surface water is scarce."[34]

Geology and morphology

Iridium clay layer
The piece of clay, held by Walter Alvarez, that sparked research into the impact theory. The greenish-brown band in the center is extremely rich in iridium.

In their 1991 paper, Hildebrand, Penfield and company described the geology and composition of the impact feature.[35] The rocks above the impact feature are layers of marl and limestone reaching to a depth of almost 1,000 m (3,300 ft). These rocks date back as far as the Paleocene.[36] Below these layers lie more than 500 m (1,600 ft) of andesite glass and breccia. These andesitic igneous rocks were only found within the supposed impact feature, as is shocked quartz.[36] The K–Pg boundary inside the feature is depressed to 600 to 1,100 m (2,000 to 3,600 ft) compared with the normal depth of about 500 m (1,600 ft) measured 5 km (3 mi) away from the impact feature.[37]

Along the edge of the crater are clusters of cenotes or sinkholes,[38] which suggest that there was a water basin inside the feature during the Neogene period, after the impact.[37] The groundwater of such a basin would have dissolved the limestone and created the caves and cenotes beneath the surface.[39] The paper also noted that the crater seemed to be a good candidate source for the tektites reported at Haiti.[40]

Astronomical origin of asteroid

In September 2007, a report published in Nature proposed an origin for the asteroid that created the Chicxulub crater.[30] The authors, William F. Bottke, David Vokrouhlický, and David Nesvorný, argued that a collision in the asteroid belt 160 million years ago resulted in the Baptistina family of asteroids, the largest surviving member of which is 298 Baptistina. They proposed that the "Chicxulub asteroid" was also a member of this group. The connection between Chicxulub and Baptistina is supported by the large amount of carbonaceous material present in microscopic fragments of the impactor, suggesting the impactor was a member of a rare class of asteroids called carbonaceous chondrites, like Baptistina.[41] According to Bottke, the Chicxulub impactor was a fragment of a much larger parent body about 170 km (106 mi) across, with the other impacting body being around 60 km (37 mi) in diameter.[41][42]

In 2011, new data from the Wide-field Infrared Survey Explorer revised the date of the collision which created the Baptistina family to about 80 million years ago. This makes an asteroid from this family highly improbable to be the asteroid that created the Chicxulub crater, as typically the process of resonance and collision of an asteroid takes many tens of millions of years.[43] In 2010, another hypothesis was offered which implicated the newly discovered asteroid P/2010 A2, a member of the Flora family of asteroids, as a possible remnant cohort of the K/Pg impactor.[44]

Chicxulub and mass extinction

The Chicxulub Crater lends support to the theory postulated by the late physicist Luis Alvarez and his son, geologist Walter Alvarez, that the extinction of numerous animal and plant groups, including non-avian dinosaurs, may have resulted from a bolide impact (the Cretaceous–Paleogene extinction event). Luis and Walter Alvarez, at the time both faculty members at the University of California, Berkeley, postulated that this enormous extinction event, which was roughly contemporaneous with the postulated date of formation for the Chicxulub crater, could have been caused by just such a large impact.[45] The age of the rocks marked by the impact shows that this impact structure dates from roughly 66 million years ago, the end of the Cretaceous period, and the start of the Paleogene period. It coincides with the K–Pg boundary, the geological boundary between the Cretaceous and Paleogene. The impact associated with the crater is thus implicated in the Cretaceous–Paleogene extinction event, including the worldwide extinction of non-avian dinosaurs. This conclusion has been the source of controversy.

In March 2010, forty-one experts from many countries reviewed the available evidence: 20 years' worth of data spanning a variety of fields. They concluded that the impact at Chicxulub triggered the mass extinctions at the K–Pg boundary.[46][47] In 2013 a study compared isotopes in impact glass from the Chicxulub impact with the same isotopes in ash from the boundary where the extinction event occurred in the fossil record; the study concluded that the impact glasses were dated at 66.038 ± 0.049 Ma, and the deposits immediately above the discontinuity in the geological and fossil record was dated to 66.019 ± 0.021 Ma, the two dates being within 19,000 years of each other, or almost exactly the same within experimental error.[48]

The theory is now widely accepted by the scientific community. Some critics, including paleontologist Robert Bakker, argue that such an impact would have killed frogs as well as dinosaurs, yet the frogs survived the extinction event.[49] Gerta Keller of Princeton University argues that recent core samples from Chicxulub prove the impact occurred about 300,000 years before the mass extinction, and thus could not have been the causal factor.[50] However, this conclusion is unsupported by radioactive dating and sedimentology.[46][48]

The main evidence of such an impact, besides the crater itself, is contained in a thin layer of clay present in the K–Pg boundary across the world. In the late 1970s, the Alvarezes and colleagues reported that it contained an abnormally high concentration of iridium.[51] Iridium levels in this layer reached 6 parts per billion by weight or more compared to 0.4 for the Earth's crust as a whole;[52] in comparison, meteorites can contain around 470 parts per billion of this element.[53] It was hypothesized that the iridium was spread into the atmosphere when the impactor was vaporized and settled across the Earth's surface amongst other material thrown up by the impact, producing the layer of iridium-enriched clay.[54] Similarly, an iridium anomaly in core samples from the Pacific Ocean suggested the Eltanin impact of about 2.5 million years ago.[55][56]

A more recent discovery is believed to demonstrate evidence of the scope of the destruction from the impact. In a March 2019 article in the Proceedings of the National Academy of Sciences, an international team of twelve scientists revealed the contents of a site discovered near Bowman, North Dakota that appeared to show a devastating mass destruction of an ancient lake and its inhabitants at the time of the Chicxulub impact. In the paper, the group claims that the geology of the site is strewn with fossilized trees and remains of fish and other animals. The lead researcher, Robert A. DePalma of the University of Kansas, was quoted in the New York Times as stating that “[Y]ou would be blind to miss the carcasses sticking out... It is impossible to miss when you see the outcrop.” Evidence correlating this find to the Chicxulub impact included tektites bearing "the unique chemical signature of other tektites associated with the Chicxulub event" found in the gills of fish fossils and embedded in amber, an iridium-rich top layer that is considered another signature of the event, and an atypical lack of scavenging of the dead fish and animals that suggested few other species survived the event to feed off the mass death. The exact mechanism of the site's destruction has been debated as either an impact-caused tsunami or lake and river seiche activity triggered by post-impact earthquakes, though there has yet been no firm conclusion upon which researchers have settled.[57][58]

Multiple impact hypothesis

In recent years, several other craters of around the same age as Chicxulub have been discovered, all between latitudes 20°N and 70°N. Examples include the disputed Silverpit crater in the North Sea, and the Boltysh crater in Ukraine.[59][60][61] Both are much smaller than Chicxulub, but are likely to have been caused by objects many tens of meters across striking the Earth.[62] This has led to the hypothesis that the Chicxulub impact may have been only one of several impacts that happened nearly at the same time.[63] Another possible crater thought to have been formed at the same time is the larger Shiva crater, though the structure's status as an impact crater is contested.[64][65]

The collision of Comet Shoemaker–Levy 9 with Jupiter in 1994 demonstrated that gravitational interactions can fragment a comet, giving rise to many impacts over a period of a few days if the comet should collide with a planet. Comets undergo gravitational interactions with the gas giants, and similar disruptions and collisions are very likely to have occurred in the past.[64][66] This scenario may have occurred on Earth at the end of the Cretaceous, though Shiva and the Chicxulub craters might have been formed 300,000 years apart.[63][64]

In late 2006, Ken MacLeod, a geology professor from the University of Missouri, completed an analysis of sediment below the ocean's surface, bolstering the single-impact theory. MacLeod conducted his analysis approximately 4,500 kilometres (2,800 mi) from the Chicxulub crater to control for possible changes in soil composition at the impact site, while still close enough to be affected by the impact. The analysis revealed there was only one layer of impact debris in the sediment, which indicated there was only one impact.[67] Multiple-impact proponents such as Gerta Keller regard the results as "rather hyper-inflated" and do not agree with the conclusion of MacLeod's analysis, arguing that there might only be gaps of hours to days between impacts in a multiple-impact scenario (cf. Shoemaker-Levy 9) which would not leave a detectable gap in deposits.[68]

Expedition 364

Chicxulub is the only known Earth crater with a remaining impact peak ring, but it is under 600 m (2,000 ft) of sediment.[69] During April and May 2016, a joint IODP-ICDP[70][71] Mission Specific Platform Expedition no. 364 obtained the first offshore core samples from the peak ring, surrounding the central zone of the crater.[72] During Expedition 364, DES[73] drillers on the L/B Myrtle[74] collected core samples to enable ECORD[75] Science Party members to study how the peak ring formed and calculate the total impact energy.

Their target depth was 1,500 m (4,900 ft) below the bottom of the ocean,[76] but they reached an acceptable 1,335 m (4,380 ft).[72] Sample preparation and analysis are performed at Bremen, Germany.[69]

Chicxulub Wharf Yucatan Mexico
The center of the crater is near the village of Chicxulub Puerto, Yucatan.

It was announced in November 2016 that pink granite, usually found deep in the Earth's crust, had been found in drilling samples.[6][77] It suggests the impact was so great it shocked and melted rocks found deep in the crust, causing them to shoot up before falling back down to produce the peak rings.[6][77] The granite samples were also found to be lighter and weaker than normal granite, a result of the shock and extreme conditions of the impact.[78] The findings confirmed that the rock comprising the peak ring had originated deep in the earth, and was ejected to the surface.[6] It had been subjected to immense pressures and forces and had been melted by heat and shocked by pressure from its usual state into its present form in just minutes; the fact that the peak ring was made of granite was also significant, since granite is not a rock found in sea-floor deposits, originating much deeper in the earth, and had been ejected to the surface by the immense pressures of impact.[77]

Gypsum, a sulfate-containing rock that is usually present in the shallow seabed of the region, had been almost entirely removed and likely vaporized to enter the atmosphere, an event immediately followed by a megatsunami sufficient to lay down the largest-known layered bed of sand, around 100 m (330 ft) deep and separated by grain size, directly above the peak ring.[79] These types of sand deposits are caused by extreme water movement, where the larger and heavier sand grains settle first, followed by lighter and smaller grains.

Taken together, analyses indicate that the impactor was large enough to create a 190-kilometre (120 mi) peak ring, to melt, shock and eject granite from many kilometres within the earth, to create colossal water movements, and to eject an immense quantity of vaporized rock and sulfates into the atmosphere, where they would have persisted over years to decades.[6][79] This global dispersal of dust and sulfates would have led to a sudden and catastrophic effect on the climate worldwide, large temperature drops, and devastated the food chain. The researchers stated that the impact generated an environmental calamity that extinguished life, but it also induced a vast subsurface hydrothermal system that became an oasis for the recovery of life.[77][80]

A program on British television in 2017[81] described that the drilling revealed, from top down: thick Cenozoic limestone, about 600 m (2,000 ft); a graded sediment deposit from the megatsunami, over 100 m (330 ft) thick; the impact melted basement granite from the Earth's midcrust with shocked quartz. The peak ring itself did not contain the calcium sulphate that the rocks in the area around contain, leading the program makers to conclude that all the calcium sulphate in the crater area had been vaporized into the atmosphere and had become a dense sulphur dioxide veil stopping the sunlight. As additional clues of the resulting megatsunami found in a New Jersey, USA quarry, a dense marine bone bed was found on the Cretaceous–Paleogene boundary containing a mixture of dead sea animals with little or no damage from scavengers or predators. Also related to this tsunami was a dense dinosaur bone bed on the Cretaceous–Paleogene boundary found in Patagonia.

See also


  1. ^ "PIA03379: Shaded Relief with Height as Color, Yucatan Peninsula, Mexico". Shuttle Radar Topography Mission. NASA. Retrieved October 28, 2010.
  2. ^ a b c Durand-Manterola, H. J.; Cordero-Tercero, G. (2014). "Assessments of the energy, mass and size of the Chicxulub Impactor". arXiv:1403.6391 [astro-ph.EP].
  3. ^ a b Renne, P. R.; Deino, A. L.; Hilgen, F. J.; Kuiper, K. F.; Mark, D. F.; Mitchell, W. S.; Morgan, L. E.; Mundil, R.; Smit, J. (2013). "Time Scales of Critical Events Around the Cretaceous-Paleogene Boundary" (PDF). Science. 339 (6120): 684–687. Bibcode:2013Sci...339..684R. doi:10.1126/science.1230492. ISSN 0036-8075. PMID 23393261.
  4. ^ a b "Chicxulub". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved December 30, 2008.
  5. ^ a b Penfield.
  6. ^ a b c d e St. Fleur, Nicholas (November 17, 2016). "Drilling Into the Chicxulub Crater, Ground Zero of the Dinosaur Extinction". The New York Times. Retrieved November 4, 2017.
  7. ^ Becker, Luann (2002). "Repeated Blows" (PDF). Scientific American. 286 (3): 76–83. Bibcode:2002SciAm.286c..76B. doi:10.1038/scientificamerican0302-76. PMID 11857903. Retrieved January 28, 2016.
  8. ^ Kornel, Katherine (September 10, 2019). "A New Timeline of the Day the Dinosaurs Began to Die Out - By drilling into the Chicxulub crater, scientists assembled a record of what happened just after the asteroid impact". The New York Times. Retrieved September 25, 2019.
  9. ^ Verschuur, 20–21.
  10. ^ a b c d Bates.
  11. ^ Verschuur, 20.
  12. ^ Weinreb.
  13. ^ Mason.
  14. ^ Hildebrand, Penfield, et al.
  15. ^ a b Hildebrand interview: 'Similar deposits of rubble occur all across the southern coast of North America […] indicate that something extraordinary happened here.'
  16. ^ a b Morás.
  17. ^ Frankel, 50.
  18. ^ Hildebrand interview.
  19. ^ Pope, Baines, et al.
  20. ^ Sharpton & Marin.
  21. ^ "Dinosaur extinction: Scientists estimate 'most accurate' date". BBC News.
  22. ^ Adamsky and Smirnov, 19.
  23. ^ a b Amos, Jonathan (May 15, 2017). "Dinosaur asteroid hit 'worst possible place'". BBC News, Science and Environment. Retrieved August 19, 2017.
  24. ^ a b Bryant, Edward (June 2014). Tsunami: The Underrated Hazard. Springer. p. 178. ISBN 978-3-319-06133-7.
  25. ^ Palmer, Jane (February 25, 2016). "We Finally Know How Much the Dino-Killing Asteroid Reshaped Earth". Smithsonian Institution. Retrieved February 26, 2016.
  26. ^ Melosh, interview.
  27. ^ Melosh. "On the ground, you would feel an effect similar to an oven on broil, lasting for about an hour [...] causing global forest fires."
  28. ^
  29. ^ Hildebrand, Penfield, et al.; 5.
  30. ^ a b Perlman.
  31. ^ Pope, Ocampo, et al.
  32. ^ Lomax, B.; Beerling D.; Upchurch Jr. G.; Otto-Bliesner B. (2001). "Rapid (10-yr) recovery of terrestrial productivity in a simulation study of the terminal Cretaceous impact event". Earth and Planetary Science Letters. 192 (2): 137–144. Bibcode:2001E&PSL.192..137L. doi:10.1016/S0012-821X(01)00447-2.
  33. ^ Marc Airhart (January 1, 2008). "Seismic Images Show Dinosaur-Killing Meteor Made Bigger Splash".
  34. ^ Winemiller, Terance L. (2007), The Chicxulub Meteor Impact and Ancient Locational Decisions On the Yucatán Peninsula, Mexico: the Application of Remote Sensing, GIS, and GPS in Settlement Pattern Studies (PDF), Tampa, Florida: American Society for Photogrammetry and Remote Sensing, retrieved October 2, 2012
  35. ^ Hildebrand, Penfield, et al.; 1.
  36. ^ a b Hildebrand, Penfield, et al.; 3.
  37. ^ a b Hildebrand, Penfield, et al.; 4.
  38. ^ "Meteor Impact Site – Earth: The biography". National Geographic. July 11, 2008. Retrieved August 19, 2015.
  39. ^ Kring, "Discovering the Crater".
  40. ^ Sigurdsson.
  41. ^ a b Bottke, Vokrouhlicky, Nesvorny.
  42. ^ Ingham.
  43. ^ Plotner, Tammy (2011). "Did Asteroid Baptistina Kill the Dinosaurs? Think other WISE..." Universe Today. Retrieved September 19, 2011.
  44. ^ Reuters Editorial (February 2, 2010). "Smashed asteroids may be related to dinosaur killer". Reuters.
  45. ^ Alvarez, W. interview.
  46. ^ a b Schulte, et al., 2010
  47. ^ Rincon.
  48. ^ a b Renne, Paul (February 8, 2013). "Time Scales of Critical Events Around the Cretaceous-Paleogene Boundary" (PDF). Science. 339 (6120): 684–7. Bibcode:2013Sci...339..684R. doi:10.1126/science.1230492. PMID 23393261.
  49. ^ Kring, "Environment Consequences".
  50. ^ Keller, et al.
  51. ^ Alvarez.
  52. ^ Web Elements.
  53. ^ Quivx.
  54. ^ Mayell.
  55. ^ Kyte, Frank T.; Zhiming Zhou; John T. Wasson (1981). "High noble metal concentrations in a late Pliocene sediment". Nature. 292 (5822): 417–420. Bibcode:1981Natur.292..417K. doi:10.1038/292417a0. ISSN 0028-0836.
  56. ^ Gersonde, R.; F. T. Kyte; T. Frederichs; U. Bleil; H. W. Schenke; G. Kuhn (2005). "The late Pliocene impact of the Eltanin asteroid into the Southern Ocean – Documentation and environmental consequences" (PDF). Geophysical Research Abstracts. European Geosciences Union. Retrieved October 8, 2012.
  57. ^ "Stunning discovery offers glimpse of minutes following 'dinosaur-killer' Chicxulub impact". March 29, 2019. Retrieved April 10, 2019.
  58. ^ "Fossil Site Reveals Day That Meteor Hit Earth and, Maybe, Wiped Out Dinosaurs". March 29, 2019. Retrieved April 10, 2019.
  59. ^ Riddle, Dawne (December 2009). "Silverpit "not crater"". Geological Society of London. Retrieved April 10, 2013.
  60. ^ Stewart, Allen.
  61. ^ Kelley, Gurov.
  62. ^ Stewart.
  63. ^ a b Mullen, "Multiple Impacts".
  64. ^ a b c "Mass extinctions: I am become Death, destroyer of worlds". The Economist. October 22, 2009. Retrieved October 24, 2009.
  65. ^ Mullen, "Shiva".
  66. ^ Weisstein.
  67. ^ Than.
  68. ^ Dunham.
  69. ^ a b de Régules, Sergio (September 2015). "Revisiting the crater of doom". Physics World. 28 (9): 33–36. Bibcode:2015PhyW...28i..33D. doi:10.1088/2058-7058/28/9/35.
  70. ^ "ESO – Chicxulub K-Pg Impact Crater Expedition 364". Archived from the original on May 10, 2016.
  71. ^ "ICDP Homepage".
  72. ^ a b Amos, Jonathan (May 25, 2016). "Chicxulub 'dinosaur' crater drill project declared a success". BBC News. Retrieved May 25, 2016.
  73. ^ "DOSECC High Quality Core Drilling & Exploration Services".
  74. ^ "Liftboat Myrtle – Self-Elevating Vessel – Offshore Liftboat Services – Montco Offshore Liftboats".
  75. ^ "ESO – Chicxulub K-Pg Impact Crater Expedition 364". Archived from the original on May 10, 2016.
  76. ^ Amos, Jonathan (April 5, 2016). "Project to drill into 'dinosaur crater' gets under way". BBC News. Retrieved April 5, 2016.
  77. ^ a b c d Chicxulub and the Exploration of Large Peak-Ring Impact Craters through Scientific Drilling (PDF). David A. Kring, Philippe Claeys, Sean P.S. Gulick, Joanna V. Morgan, and Gareth S. Collins. The Geological Society of America. 2017.
  78. ^ St. Fleur, Nicholas. "Drilling Into the Chicxulub Crater, Ground Zero of the Dinosaur Extinction". The New York Times. Retrieved November 19, 2016.
  79. ^ a b Hand, Eric (November 17, 2016). "Updated: Drilling of dinosaur-killing impact crater explains buried circular hills". Scientific American. Retrieved November 4, 2017.
  80. ^ Probing the impact-generated hydrothermal system in the peak ring of the Chicxulub crater and its potential as a habitat. (PDF) Barry J. Shaulis, Ulrich Riller, Charles Cockell, Marco J., and L. Coolen. Lunar and Planetary Science XLVIII (2017)
  81. ^ The Day the Dinosaurs Died, BBC2 television, July 1, 2017, 6 to 7 pm


Further reading

External links

1991 in science

The year 1991 in science and technology involved many significant events, some listed below.

Adriana Ocampo

Adriana C. Ocampo is a Colombian planetary geologist and a Science Program Manager at NASA Headquarters. She and her colleagues were the first to identify a ring of cenotes via satellite images, the only surface impression of the buried Chicxulub crater, research that contributed significantly to understanding of this impact crater; Ocampo has subsequently led at least seven research expeditions to the Chicxulub site. As well, in 1996, Ocampo and her colleagues discovered the Aorounga Crater Chain in Chad.. She continues to search for new impact craters, and with her team recently reported on a possible crater near Cali, Colombia. Ocampo has had an asteroid name after her, in recognition of her contributions to space exploration.

Alvarez hypothesis

The Alvarez hypothesis posits that the mass extinction of the dinosaurs and many other living things during the Cretaceous–Paleogene extinction event was caused by the impact of a large asteroid on the Earth. Prior to 2013, it was commonly cited as having happened about 65 million years ago, but Renne and colleagues (2013) gave an updated value of 66 million years. Evidence indicates that the asteroid fell in the Yucatán Peninsula, at Chicxulub, Mexico. The hypothesis is named after the father-and-son team of scientists Luis and Walter Alvarez, who first suggested it in 1980. Shortly afterwards, and independently, the same was suggested by Dutch paleontologist Jan Smit.

In March 2010, an international panel of scientists endorsed the asteroid hypothesis, specifically the Chicxulub impact, as being the cause of the extinction. A team of 41 scientists reviewed 20 years of scientific literature and in so doing also ruled out other theories such as massive volcanism. They had determined that a 10–15 km (6–9 mi) space rock hurtled into earth at Chicxulub. For comparison, the Martian moon Phobos is 11 km (7 mi) and Mount Everest is just under 9 km (5.6 mi). The collision would have released the same energy as 100,000,000 megatonnes of TNT (4.2×1023 J), over a billion times the energy of the atomic bombs dropped on Hiroshima and Nagasaki.A 2016 drilling project into the peak ring of the crater strongly supported the hypothesis, and confirmed various matters that had been unclear until that point. These included the fact that the peak ring comprised granite (a rock found deep within the earth) rather than typical sea floor rock, which had been shocked, melted, and ejected to the surface in minutes, and evidence of colossal seawater movement directly afterwards from sand deposits. Crucially the cores also showed a near complete absence of gypsum, a sulfate-containing rock, which would have been vaporized and dispersed as an aerosol into the atmosphere, confirming the presence of a probable link between the impact and global longer-term effects on the climate and food chain.

Boltysh crater

The Boltysh crater or Bovtyshka crater is an impact crater in the Kirovohrad Oblast of Ukraine, near the village of Bovtyshka. The crater is 24 kilometres (15 mi) in diameter and its age of 65.17 ± 0.64 million years, based on argon dating techniques, is within error of that of Chicxulub crater in Mexico and of the Cretaceous–Paleogene boundary (K–Pg boundary). The Chicxulub impact is believed to have caused the mass extinction at the end of the Cretaceous period, which included the extinction of the dinosaurs. The Boltysh impact likely occurred several thousand years before Chicxulub, suggesting the extinction event may have been driven by multiple meteor strikes over an extended period of time about 65 million years ago.


A cenote (English: or ; American Spanish: [seˈnote]) is a natural pit, or sinkhole, resulting from the collapse of limestone bedrock that exposes groundwater underneath. Especially associated with the Yucatán Peninsula of Mexico, cenotes were sometimes used by the ancient Maya for sacrificial offerings.

The term derives from a word used by the low-land Yucatec Maya—ts'onot—to refer to any location with accessible groundwater. Cenotes are common geological forms in low latitude regions, particularly on islands, coastlines, and platforms with young post-Paleozoic limestones that have little soil development.

Chicxulub Pueblo

Chicxulub Pueblo (Mayan pronunciation: [tʃʼikʃuluɓ] Ch’ik Xulub) is a town, and surrounding municipality of the same name, in the Mexican state of Yucatán.

At the census of 2010, the town had a population of 4,080 people.

Chicxulub is most famous for being near the geographic center of the Chicxulub crater, an impact crater discovered by geologists on the Yucatán Peninsula and extending into the ocean. It was created by the impact some 66 million years ago of the Chicxulub impactor, an asteroid or comet which caused the Cretaceous–Paleogene extinction event, which led to the demise of the dinosaurs. The coastal village (or puerto) of Chicxulub, 6 km east of the nearest town, Progreso, lies almost exactly on the geographic center of the crater.

The name Chicxulub is Yucatec Maya language, where ch’ik means "flea" or "tick", and xulub’ means "devil, demon, or horns".

Chicxulub Pueblo Municipality

Chicxulub Pueblo Municipality (In the Yucatec Maya Language: “horn lit place or flea devil”) is one of the 106 municipalities in the Mexican state of Yucatán containing (196.72 km2) of land and located roughly 25 km north of the city of Mérida. The area was considered the epicenter of the Chicxulub crater.

Chicxulub impactor

The Chicxulub impactor ( CHEEK-shə-loob), also known as the K/Pg impactor and (more speculatively) as the Chicxulub asteroid, was an asteroid or other celestial body some 11 to 81 kilometres (7 to 50 mi) in diameter and having a mass between 1.0×1015 and 4.6×1017 kg, which struck the Earth at the end of the Cretaceous period, 66 million years ago, creating the Chicxulub crater. It impacted a few miles from the present-day town of Chicxulub in Mexico, after which the impactor and its crater are named. Because the estimated date of the object's impact and the Cretaceous–Paleogene boundary (K–Pg boundary) coincide, there is a scientific consensus that its impact was the Cretaceous–Paleogene extinction event which caused the death of the planet's non-avian dinosaurs and many other species.The impactor's crater is over 150 kilometres (93 miles) in diameter making it the one of the largest known impact craters on Earth.

Cretaceous–Paleogene boundary

The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K-T) boundary, is a geological signature, usually a thin band of rock. K, the first letter of the German word Kreide (chalk), is the traditional abbreviation for the Cretaceous Period and Pg is the abbreviation for the Paleogene Period.

The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at around 66 Ma (million years ago), with radiometric dating yielding a more precise age of 66.043 ± 0.011 Ma.The K–Pg boundary is associated with the Cretaceous–Paleogene extinction event, a mass extinction which destroyed a majority of the world's Mesozoic species, including all dinosaurs except for birds.Strong evidence exists that the extinction coincided with a large meteorite impact at the Chicxulub crater and the generally accepted scientific theory is that this impact triggered the extinction event.

Cretaceous–Paleogene extinction event

The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary (K–T) extinction, was a sudden mass extinction of some three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the exception of some ectothermic species such as the leatherback sea turtle and crocodiles, no tetrapods weighing more than 25 kilograms (55 lb) survived. It marked the end of the Cretaceous period and with it, the entire Mesozoic Era, opening the Cenozoic Era that continues today.

In the geologic record, the K–Pg event is marked by a thin layer of sediment called the K–Pg boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows high levels of the metal iridium, which is rare in the Earth's crust, but abundant in asteroids.As originally proposed in 1980 by a team of scientists led by Luis Alvarez and his son Walter Alvarez, it is now generally thought that the K–Pg extinction was caused by the impact of a massive comet or asteroid 10 to 15 km (6 to 9 mi) wide, 66 million years ago, which devastated the global environment, mainly through a lingering impact winter which halted photosynthesis in plants and plankton. The impact hypothesis, also known as the Alvarez hypothesis, was bolstered by the discovery of the 180-kilometer-wide (112 mi) Chicxulub crater in the Gulf of Mexico's Yucatán Peninsula in the early 1990s, which provided conclusive evidence that the K–Pg boundary clay represented debris from an asteroid impact. The fact that the extinctions occurred simultaneously provides strong evidence that they were caused by the asteroid. A 2016 drilling project into the Chicxulub peak ring confirmed that the peak ring comprised granite ejected within minutes from deep in the earth, but contained hardly any gypsum, the usual sulfate-containing sea floor rock in the region: the gypsum would have vaporized and dispersed as an aerosol into the atmosphere, causing longer-term effects on the climate and food chain.

Other causal or contributing factors to the extinction may have been the Deccan Traps and other volcanic eruptions, climate change, and sea level change.

A wide range of species perished in the K–Pg extinction, the best-known being the non-avian dinosaurs. It also destroyed a plethora of other terrestrial organisms, including some mammals, pterosaurs, birds, lizards, insects, and plants. In the oceans, the K–Pg extinction killed off plesiosaurs and the giant marine lizards (Mosasauridae) and devastated fish, sharks, mollusks (especially ammonites, which became extinct), and many species of plankton. It is estimated that 75% or more of all species on Earth vanished. Yet the extinction also provided evolutionary opportunities: in its wake, many groups underwent remarkable adaptive radiation—sudden and prolific divergence into new forms and species within the disrupted and emptied ecological niches. Mammals in particular diversified in the Paleogene, evolving new forms such as horses, whales, bats, and primates. Birds, fish, and perhaps lizards also radiated.

Deccan Traps

The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India (17–24°N, 73–74°E). They are one of the largest volcanic features on Earth. They consist of multiple layers of solidified flood basalt that together are more than 2,000 m (6,600 ft) thick, cover an area of c. 500,000 km2 (200,000 sq mi), and have a volume of c. 1,000,000 km3 (200,000 cu mi). Originally, the Deccan Traps may have covered c. 1,500,000 km2 (600,000 sq mi), with a correspondingly larger original volume.

East Warburton Basin

The East Warburton Basin in South Australia is the site of a hypothesised large impact crater of the Carboniferous period (around 360-300 million years ago). The subterranean structure lies buried at a depth of ~4 km, and measures a minimum of 200 km in diameter. For comparison, Chicxulub crater is about 180 km in diameter.

Scientists proposed the impact formation through analysis of shocked quartz grains from the area after a circular anomaly appeared in seismic tomography studies of the region.

Flora family

The Flora family (adj. Florian; FIN: 402; also known as Ariadne family) is a prominent family of stony asteroids located in the inner region of the asteroid belt. It is one of the largest families with more than 13,000 known members, or approximately 3.5% of all main-belt asteroids.The origin and properties of this family are relatively poorly understood. It is a very broad family which gradually fades into the surrounding background population. While the largest members, 8 Flora and 43 Ariadne, are located near the edge, there are several distinct groupings within the family, possibly created by later, secondary collisions. Due to this complex internal structure and the poorly defined boundaries, the Flora family has also been described as an asteroid clan. Only few interlopers have been identified. This family may be the source of the impactor that formed the Chicxulub crater, the likely culprit in the extinction of the dinosaurs.

History of science and technology in Mexico

The history of science and technology in Mexico spans many years. Ancient Mexican civilizations developed mathematics, astronomy, and calendrics, and solved technological problems of water management for agriculture and flood control in Central Mexico. Following the Spanish conquest in 1521, New Spain (colonial Mexico) was brought into the European sphere of science and technology. The Royal and Pontifical University of Mexico, established in 1551, was a hub of intellectual and religious development in colonial Mexico for over a century. During the Spanish American Enlightenment in Mexico, the colony made considerable progress in science, but following the war of independence and political instability in the early nineteenth century, progress stalled. During late 19th century under the regime of Porfirio Díaz, the process of industrialization began in Mexico. Following the Mexican Revolution, a ten-year civil war, Mexico made significant progress in science and technology. During the 20th century, new universities, such as the National Polytecnical Institute, Monterrey Institute of Technology and research institutes, such as those at the National Autonomous University of Mexico, were established in Mexico.

According to the World Bank, Mexico is Latin America's largest exporter of high-technology goods (High-technology exports are manufactured goods that involve high R&D intensity, such as in aerospace, computers, pharmaceuticals, scientific instruments, and electrical machinery) with $40.7 billion worth of high-technology goods exports in 2012. Mexican high-technology exports accounted for 17% of all manufactured goods in the country in 2012 according to the World Bank.

Kevin O. Pope

Kevin O. Pope is the former NASA archaeologist and founder of Geo Eco Arch Research who helped connect the Chicxulub Crater to the Cretaceous–Paleogene extinction event. In 2002, Pope, along with the Geological Society of America, released a press release saying that the original Cretaceous–Paleogene impact event by a 10 km diameter asteroid was not large enough to trigger a dust-connected 'cosmic winter'. It would require significantly more fine dust to be generated in order to create this effect than has been detected [1]. Instead he proposes that sulfate aerosols and ash from global fires was enough to create the effect of global cooling by interfering with photosynthesis.

He has also questioned whether the current size of an asteroid thought to be large enough to create a global impact is in fact too small. The current size suggestion is between 1.5–2 km which Pope argues would only create regional devastation.

He has also worked on investigating quartz found in Australia that has been "shocked" to such the extent that it has become deformed. He believes that these may have formed due to the Bedout impact as it would require enormous forces to deform the quartz. The Bedout impact coincides with the Permian–Triassic extinction event, the period known at the end-Permian where 90% of Marine and 80% of land life disappeared.

Peak ring (crater)

A peak ring crater is a type of complex crater, which is different from a multi-ringed basin or central-peak crater. A central peak is not seen; instead, a roughly circular ring or plateau, possibly discontinuous, surrounds the crater's center, with the crater rim still farther out from the center.

Prairie Bluff Formation

The Prairie Bluff Chalk Formation is a geological formation in North America, within the U.S. state of Alabama. The chalk was formed by marine sediments deposited along the eastern edge of the Mississippi embayment during the Maastrichtian stage of the Late Cretaceous. It is a unit of the Selma Group and marks the end of the Cretaceous in Alabama. Evidence has been found within the formation at Braggs, Moscow, and Millers Ferry in Alabama indicating an instantaneous to brief erosional event, most likely a tsunami, at the Cretaceous–Paleogene boundary (K–T boundary). It is hypothesized that this event, along with faulting and liquification of the Prairie Bluff Chalk, is related to the meteorite impact at the Chicxulub crater site, directly south, across the Gulf of Mexico, from the formation.

World Digital Magnetic Anomaly Map

The World Digital Magnetic Anomaly Map (WDMAM) was first made available by the Commission for the Geological Map of the World in 2007. Compiled with data from governments and institutes, the project was coordinated by the International Association of Geomagnetism and Aeronomy, and was presented by Mike Purucker of NASA and Colin Reeves of the Netherlands. As of 2007, it was considered to be "the first truly global compilation of lithospheric magnetic field observations." and further improvements dated to 2009 relate to the full spectrum magnetic anomaly grid of the United States and also data of global marine magnetic anomaly.Some of the magnetic anomalies shown in the WDMAM generally relates to the altitude level of 5 kilometres (3.1 mi). Some of the significant features represented are of the Bangui Anomaly in the Central African Republic, the Chicxulub crater, the Thromsberg anomaly, the Richat Structure, the Atlantic ridge, the Bay of Biscay, the Sunda Arc and the Paris Basin.


Hacienda Yaxcopoil (YASH-coh-poh-EEL) is a town and hacienda located near Merida Mexico, in the Umán Municipality, Yucatán. Hacienda Yaxcopoil dates back to the 17th century, the name Yaxcopoil means "the place of the green alamo trees" in the Yucatec Maya language, one of which still stands in front of the hacienda. The Hacienda represents the history of three great periods in the Yucatán Peninsula: the pre-Columbian period (there are ruins nearby), the Spanish colonial period, and the boom years of henequen cultivation during the late 19th and early 20th century. Hacienda Yaxcopoil was purchased by Don Donaciano García Rejón and his wife Doña Mónica Galera in 1864, and has been owned by members of the same family since that time.

Hacienda Yaxcopoil was once considered one of the most important rural estates in the Yucatán. The entire property at when it was at its largest covered 22,000 acres (89 km2). It operated first as a cattle ranch and later as a henequen plantation. Over time, due to continuous political, social and economic changes, the estate has been reduced to less than 3% of its original size.

Inside the hacienda, besides many original pieces of furniture, are two oil paintings showing Don Donaciano García Rejón and his wife Doña Mónica Galera. The office contains books, maps, documents, and other collections that form part of the archives of Yaxcopoil. These archives have been preserved faithfully and are available to valid researchers.

The patron saint of the hacienda is San Gerónimo de Yaxcopoil, who is still venerated in the pueblo near the hacienda. In the orchard, the water tanks and original US-made pump still supply water for hacienda, which now operates as a museum and guest house.

In the back of the museum is the "Maya Room." There are numerous pieces of ancient pottery and other archaeological relics of the "classic period" (A.D. 250-900) found in the nearby Mayan ruins of Yaxcopoil. There are numerous unexcavated pyramids with heights that vary from six to twenty meters, a court for ceremonial ball games, and stelae, which are scattered in an area of about eight square kilometers.

Hacienda Yaxcopoil also a well-preserved machine house, or casa de maquina, where the henequen shredding machines (planta desfibradora) were used to render fibers from the henequen plant. The engine room has been maintained in good condition with a 100 hp (75 kW) German diesel motor made by Körting (Hannover) in 1913. The engine was used until 1984, when the production of henequen fiber in the hacienda ended, after more than a century in operation.

Hacienda Yaxcopoil has been preserved but not renovated, and now operates as a museum, as well as a location for photo and film shoots. There is also a guest house on the property that can be rented for overnite stay.

Proposed K–Pg boundary craters
≥20 km diameter


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