The Deccan Volcanism Hypothesis

Background: In 1980 a team of scientists led by Luis Alvarez and his son Walter Alvarez (source) proposed a possible cause of the extinction of dinosaurs around 65 million years ago. They believed that a massive impact of a comet or an asteroid triggered this event. According to the Alvarez Hypothesis this impact ejected sediment into the atmosphere which led to a decrease in photosynthesis. Plants died around the world and the global ecosystems collapsed. Evidence that supports this proposal includes large amounts of iridium in the rock layer during this period of time. Iridium is an element rarely found on earth but one that occurs in high levels in extraterrestrial rock like comets and asteroids. Another piece of evidence includes the discovery of the Chicxulub crater, a large impact crater in the Gulf of Mexico that is dated to this same time period. 1. Complete the graphic organizer below to identify the evidence and reasoning in the Alvares Argument. Claim An asteroid impact caused the extinction of the dinosaurs. Evidence Focus on Identify the evidence the Alvarez's used to support their claim. Fridium -Large amounts of Ir in rock layer during this period of time when dinosaur's went extinct. - Ir is abundant in comets lasteroid Reasoning Identify logical reasoning connecting the evidence to the claim. are If dinosaurs went extinct 65,000,000 years ago, and high levels of Ir fand in rock layers corresponding to 65000000 years ago then it can be concluded that Comets and or asteroids could have hit Earth during that time period. since asteroids have high levels of Ir. This work is licensed by the author(s) under a Creative Commons Attribution-NonCommercial 4.0 International License. Page 1 The Deccan Volcanism Hypothesis Work published in 2014 by Gerta Keller (pictured to the right) proposed an additional cause for the dinosaur extinction, the Deccar Volcanism Hypothesis. Watch this YouTube video clip to gather more evidence supporting this argument. A transcript of the video can be found below. Credit: Peter Murphy DECCAN VOLCANISM 2. Complete the graphic organizer below to identify the evidence and reasoning in the Keller Argument. Claim Deccan volcanism caused the extinction of the dinosaurs. Evidence Identify the evidence that Keller used to support her claim. Deccan volcanism time period coincides with Earth's life extinction period. Reasoning Identify logical reasoning connecting the evidence to the claim. Video: 1:20 would Repeated volk, eruptions for 350,000 yrs. caused toxic gases: poisoned creature's worldwide initialed climate, facid destroy ocean vegetation. CO₂ would raise air temp, and acidify acebus, rain leading to plankton death larger matiner and lo land. page This work is licensed by the author(s) under a Creative Commons Attribution-NonCommercial 4.0 International License. dis The Shade of Cainan New Evidence In 2020 scientists from England and Spain published fossil and climate data during this period of time. You will use this new information to support either the Alvarez or Keller arguments described so far. tridium Vekanism 120^ prime prime 0' 0^ prime prime W 60 deg * 0' 0^ prime prime W 0°0'0" 60 deg * 0' 0^ prime prime E 120 deg * 0' 0^ prime prime E 180' * 0' 0^ prime prime 2 Indial 1 90 ^ prime prime 0^ prime prime 60 deg * 0' 0^ * N^ * Location L00N 0^ prime prime 0' 0^ prime prime = 30 deg * 0' 0^ prime prime S^ prime 60 deg * 0' 0^ prime prime S^ prime 3 4 5 2 -600'0"1 6 - 30 deg * 0' 0^ prime prime 1 - 0 ^ prime prime 0^ prime prime -30'0'0": -60°0′0": 90 deg * 0' 0^ prime prime + 150 deg * 0' 0^ prime prime W T 90 deg * 0 deg 0^ prime prime W 30 ^ prime prime 0^ prime prime 0^ prime prime W 30 deg * 0 deg * 0 deg * E 90 deg * 0 deg * 0 deg * E 150 ^ prime prime 0^ prime prime E 90^ prime prime 0' 0^ prime prime Figure 1: Location of dinosaurs remains (body fossils, egg fragments and nesting sites) throughout the period of Deccan volcanism, Hell Creek Formation (United States); 2, Lameta Formation "(India); 3, Tremp Formation (Spain); 4, Phosphorite beds (Morocco); 5, Marilía Formation (Brazil); 6, Nemegt Formation (Mongolia). 65.8-29R ra 66- Cenozoi Paleogene 66.1- Cretaceous Jack Mayer Wood, (CC co2 global war India 1, 2, 3 global cooling BY 3.0) millum yrs ago 66 million Temp. drop-no more dinosaur remains found during India volcanism s dino's ours, in India 1, 4, 5, 6 in Ing ding fossilsi India Before volcanism 1,3,6 12 Average India 1, 2, 3 AVERAGE Figure 2: Global temperature changes along with major Deccan volcanism during the time of the dinosaur extinction. Major volcanoes are highlighted with back arrows arrews. The Chicxulub asteroid impact is also shown. Dinosaur locations from locations identified in Figure 1 are included. Jack Mayer Wood, (CC BY 3.0) [page 3 Millions of Years Ago 66.2- 30N Time and Temperatur 66.5 67- 67.65- 67.95 68.8- e Temperature (°C) This work is licensed by the author(s) under a Creative Commons Attribution-NonCommercial 4.0 International License. new 3. Use the evidence from the previous page to complete the graphic organizer below. Claim What (Circle one) →This new evidence supports the Alvarez/Asteroid Impact hypothesis. This new evidence supports the Keller/Deccan Volcanism hypothesis. This new evidence supports both hypotheses. This new evidence supports neither hypothesis. Evidence Identify the evidence from Figures 1 and 2 that support your claim. Some Fe dino.remains in India where vokanism occurred. Fig. 1. Fig 2: Temp drop after asteroid collision, no dino remains vafter that time. volcanism period, dinosaur fossils found Reasoning Use your understanding of the geologic time scale and logical reasoning to connect your evidence to your claim. Ancient P.602 Textbk: Time Boundaries are based on rock ages found in rock layers. Fossils found in rock layers indicate how long ago the life forms of those fossils lived. From Fig. 2, it can be concluded that global dinosaur extinction only occurred after asteroid impact During Deccan period only dinosaurs. extdooce osairs in regions 4,5,6 became extinct. But they still existed in #1, 23. Therefore, re, this this supports supports the hypothesis that global olinosaur extinction was caused by asteroid impact, not Deccan volkonisin, page 4 This work is licensed by the author(s) under a Creative Commons Attribution-NonCommercial 4.0 International License.