The Cretaceous-Paleogene Mass Extinction
Wil Creasy Student Number: 20921355
The Cretaceous-Paleogene boundary (K-Pg boundary) was host to one of the three largest mass extinctions in the past 500 million years. Evidence suggests it was the result of a large asteroid impact approximately 65.5 million years ago in Chicxulub, Mexico; hence why the crater it formed was named the Chicxulub crater. The crater was approximately 180 kilometres in diameter and was believed to have led to the extinction of the dinosaurs amongst many other life forms including marine plankton (calcareous nannofossils and planktonic foraminifera) (Schulte et al., 2010). Furthermore, it had a number of impacts on the atmosphere and environment including the creation of sulfuric acid rain and stratospheric dust cloud formations.
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The deposit included a millimeter thick red clay layer that includes an iridium anomaly, ejecta spherules and nickel rich spinel (Schulte et al., 2010). The age of the deposit coincides with the time of the mass extinction. It is coincidences such as this that have led scientists to believe that the mass extinction and the Chicxulub impact are related.
The Yucatan-6 borehole provided significant evidence to suggest that there was an impact event that took place. The composition of the melt rock was believed to have been the result of an impact rather than volcanic events (Kring and Boynton, 1992). What allowed scientists to confirm this, was the surviving clasts of target rock they discovered within the melt, were similar to that seen In the Manicouagan impact crater. (Kring, 2007) Furthermore, these clasts were said to be composed of shocked quarts and feldspar, which are indicative of an impact
wherever it fell to earth. Others believe a gigantic fireball, rising over Chicxulub, would have spread hot material over the planet.”
Large amounts of iridium – a chemical element that is not a part of the Earth’s crust composition – were originally found in rocks of Europe and United States, and have been found everywhere ever since. Iridium, common in meteorites, is a testable evidence of the disaster hypothesis. Gould continues that the Cretaceous debacle, which is one of five episodes of mass dying, occurred at the same time as the large comet might have smashed into the Earth. The author believes this is not merely a coincidence, rather, it is a proof of the cause-effect relationship. The demise of a wide range of habitats along with the extinction of dinosaurs gives an inestimable advantage to the disaster theory over other claims, the author adds. The comet struck the Earth, and habitats, from terrestrial to marine, died with geological suddenness. Finally, this hypothesis has had an impact on the study of an atomic war and its consequences. A nuclear war, Gould says, may cause a huge drop in temperatures and result in the extinction of humanity. Testable evidence, study, development, contribution – all this makes good science.
The fossil deposits at the Chicxulub site suggest that the mineral layer in the crater was deposited after the impact, but before the extinction of the dinosaurs and other species. Keller proposes two possible explanations for this. The first explanation is that the sediments were deposited as the backwash of a giant tsunami that occurred after the impact (Keller 2004).
The Chicxulub crater is located on Mexico’s Yucatan peninsula and evaded detection for decades because it was buried while at the same time being reserved beneath a kilometre of younger rocks and sediments. Most scientists now agree that the Chicxulub crater is evidence that a huge asteroid or comet crashed into the Earth's surface 65 million years ago causing the extinction of more than 70% of the living species on the planet, including the dinosaurs. This collision idea was first popularised in 1980 by Luis Alvarez and his son, Walter Alvarez, where they developed the Alvarez hypothesis. They were studying a one centimetre-thick layer in Italy, which
He narrowed his hunt down to a location in Denmark, where he had sent a colleague to perform an iridium analysis test at ("Asteroids and Dinosaurs: Unexpected Twists and an Unfinished Story," n.d.). When the results came back, Alvarez knew that whatever happened had not been a small-scale disaster. Once again, Alvarez was back to asking questions. What caused the increased iridium levels at the KT boundary? Except this time, he realized that his observations supported the ten year old hypothesis that had been proposed by paleontologist Dale Russell and physicist Wallace Tucker ("Asteroids and Dinosaurs: Unexpected Twists and an Unfinished Story," n.d.). They brought up the possibility of a supernova being the cause of dinosaur extinction. Supernovas are known to release high amounts of iridium, so such a hypothesis fit perfectly with Alvarez’s team’s discovery. However, the hope of having found a conclusion was short-lived. Luis Alvarez had mentioned that if said supernova had occurred that it would have released amounts of plutonium which would have been found alongside the iridium; no plutonium was found at either site. After more digging, the team came up with a new hypothesis ("Asteroids and Dinosaurs: Unexpected Twists and an Unfinished Story," n.d.). Perhaps an asteroid had struck Earth towards the end of the Cretaceous period, blowing enough dust into the atmosphere to
Dinosaurs ruled the earth for over 65 million years and thankfully for the human race, they became extinct. Ultimately, only a major catastrophe could completely wipe out an entire species, let alone an entity of dinosaurs and the debacle on the causes of dinosaur extinction have flooded the minds of paleontologists for centuries. Geologist and zoologist Stephen Jay Gould published “Sex, Drugs, Disasters, and the Extinction of Dinosaurs,” to compare scientific and speculative causes of dinosaur decimation. Personally, I found this passage very informational and enjoyed reading it. Gould provides three theories that capture the reader’s curiosity, allowing room for pondering in one’s mind.
Schulz’s article is split into five sections. The first section introduces the readers to Chris Goldfinger, a paleoseismologist at Oregon State University. Goldfinger was at a seismology conference in Kashiwa, Japan when the 2011 Tohoku
8. The periods in which there were mass extinctions are Permian – volcanic eruptions which spewed lava and put CO2 into the air which warmed the climate an estimated 6 degrees Celsius. The resulting of oxygen deficiency. And Cretaceous – asteroid or comet
The sedimentary layers of rock and soil are used by the evolutionists to argue that the layers of rock would have gradually built up over millions of years. Paul D. Ackerman in his book, It’s a Young World After All: Exciting Evidences for Recent Creation, argues that if it took millions of years to build the rock layers found in the Grand Canyon, then scientists should be able to encounter countless numbers of meteors. “With the passage of vast amounts of evolutionary time, these accumulating meteorites would be incorporated into the geologic column, and there should be many of them contained in the rock layers today.” Geologists should be coming across chunks or at least pieces of meteors when digging or observing the layers. However, they do not; which means that there must have been a catastrophic event that laid down the geologic column quickly. This would explain why there are not any indications of meteors in the geological column. Ackerman ends the chapter with a clear cut conclusion: “What do the data show? A clear result in favor of a recent creation. One survey of the literature a few years ago failed to turn up a single case of a meteorite being found in the geologic column. The meteorite clock reads clearly to the effect that the earth is not very old.”
L. Vardiman, A.A. Snelling and E.F. Chaffin (Eds.), Radioisotopes and the Age of the Earth: Results of a Young-Earth Creationist Research Initiative, Institute for Creation Research, Santee, California, and Creation Research Society, St. Joseph, Missouri, 2000.
The Cretaceous-Paleogene boundary that occurred around 65 million years ago marks one of the three largest mass extinctions in the past 500 million years. The hypotheses of Cretaceous-Tertiary boundary impact on Yucatán Peninsula, Mexico shows evidence in the Gulf of Mexico of turbidity currents, and giant waves occurring because of the impact. There is also other evidence that impact ejecta were distributed all over the world. The mineral that was ejected during this impact was iridium. Iridium is a mineral that is commonly used to indicate a rock layer from the K-T boundary. Iridium is only found naturally on extraterrestrial bodies. In addition to Iridium, shocked quartz is used to indicate the K-T boundary. Shocked quartz is unique and
It seems like something out of a low-budget, alien sci-fi movie, but there is actually some scientific data to back this theory up. Astrophysicist Daniel Whitmire suggests that the mysterious alien planet not only may have killed the dinosaurs but is causing extinction at regular intervals on Earth. These intervals are said to be every 27 million years, so it's
According to the research made by Alvarez (1980), it was due to an asteroid impact that single-handedly destroyed dinosaurs to extinction. Advocacy of this mechanism has been aided by the availability and tangibility of supporting evidence in the form of impact craters- the Chicxulub crater in the Yucatan Peninsula's date and timing of impact (dating produced an almost exact date of 65 million years ago), location, enormous size-170 km (Hildebrand et al.1991) and its high iridium content ( a metal not commonly found at the Earth's surface) make it seem that with a theoretical asteroid 10 km big caused the crater great damage at the end of the Cretaceous (Alvarez et al. 1980).
This final blow would have sent earth into a nuclear winter. According to this theory, dust caused by the asteroid collision disrupted plant growth by blocking out the sunlight needed for photosynthesis for nearly a year. A chain reaction occurred as plants died off, so did the herbivores relying on the plants, and then the carnivores that relied on the herbivores. Around 75% of species became extinct, including dinosaurs, mammals, giant marine lizards, fish, birds, and insects. Meanwhile, seawater flooded around 40% of the world’s continents ("Mass Extinctions").
The asteroid instantaneously made a hole that was 100km wide and 30km deep. Experts say that " it hit at the same energy as 100 million atomic bombs and left behind a 100-mile-wide scar known today as the Chicxulub creator” Many scientists believe that the impact of the Chicxulub asteroid played a big part in the "KT Extinction" which was the extinction of almost all life on earth, including the dinosaurs. When the bowl collapsed it left behind a 200km creator across and a couple of km deep. Later, on the centre of the crater "rebounder and collapsed again", this time it produced an inner ring. Now days a larger percentage of the creator is buried offshore, under about 600m of sediments. The parts of the crater that are still on land are cover in limestone and at the rim of the crater there is an arc of