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The Great KT Extinction Controversy

Plate tectonics of the North American Continent at the Cretaceous-Tertiary Boundary, and Implications For a Terrestrial Cause in the Great KT Extinction Controversy. The Great KT Extinction Controversy. Before 65 mya, during the Cretaceous (K), dinosaurs had roamed the Earth.

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The Great KT Extinction Controversy

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  1. Plate tectonics of the North American Continent at the Cretaceous-Tertiary Boundary, and Implications For a Terrestrial Cause in the Great KT Extinction Controversy

  2. The Great KT Extinction Controversy • Before 65 mya, during the Cretaceous (K), dinosaurs had roamed the Earth. • But by the beginning of the Tertiary (T), 65 million years ago (mya), a mass extinction had occurred that wiped out nearly 75 % of life on Earth, including the dinosaurs. • This is known as the KT Extinction Event

  3. In 1980, Dr.’s Louis and Walter Alvarez discovered a layer of clay at several sites along the KT boundary that contained high levels of iridium, as well as other exotic materials. (Alvarez, 1980) • Since iridium is rare in Earth’s crustal rocks, the Alvarez team proposed that the layer had been formed by an Extraterrestrial source, such as an asteroid. • So far, this has been the most widely accepted hypothesis.

  4. In 1981, however, Dr. Dewey McLean of Virginia Tech showed how Deccan Traps volcanism in India could have increased CO2 levels in the atmosphere causing a severe global warming event. (McLean, 1981) • Dr. McLean also showed that the asteroid theory did not explain all of the evidence found in the geologic and biologic record at the KT boundary. (McLean, 1991)

  5. For decades now, these two hypotheses have battled for top contender in the Great KT Extinction Debate, and yet, neither has been chosen as the champion. • This presentation will attempt to show that this is because it was neither an asteroid nor the Deccan Traps that caused the extinctions of 65 million years ago.

  6. In 1996, a new hypothesis was introduced that almost seemed to go unnoticed in the KT Extinction Debate. • In their book, “The Great Dinosaur Extinction Controversy”, Dr. Charles Officer and Jake Page showed that most of the evidence being used in the asteroid hypothesis could also be volcanic in nature. • They also pointed out that not only were the Deccan Traps occurring at the KT boundary, but that massive volcanism was occurring all over the world at that time. • (Officer and Page, 1996)

  7. Particularly, large magmatic events were occurring within North America that was not only coeval with the Extinctions, but also, with the uplifting of the Laramide Orogeny and the disappearance of the Western Interior Seaway.

  8. However, as no exact mechanism had been found to account for the exotic mix of materials in the KT boundary layer, this hypothesis was largely dismissed in the KT Extinction Debate.

  9. So, I wanted to know what DID cause the uplifting of the Rocky Mountains, as well as the disappearance of the Western Interior Seaway, along with massive volcanism, to occur in North America at the KT boundary? • I began to look at the Geologic formations of Western North America at the Cretaceous-Tertiary Boundary and the tectonic events that created them.

  10. The Western Interior Seaway • Before the beginning of the Laramide, Texas lay at the bottom of a shallow seaway that stretched across the interior from the Arctic Ocean to the Gulf of Mexico. This cold, salty sea is known as the Western Interior Seaway. • Before the Laramide, bays and estuaries covered most of New Mexico (Chronic, 1987); and Arizona lay along the floodplains of that ancient sea. (Chronic, 1983)

  11. Most of the fossils found at the KT boundary in North America were animals that lived within, or along the shores of, the Western Interior Seaway. • North America • in the Age of the Dinosaurs, • 75 mya. (National Geographic, • January, 1993)

  12. Officer and Page (1996) showed that the Western Interior Seaway began to disappear in the Albian and was mostly gone by the Maastrichtian, before 65 mya, caused by the uplifting of western North America. • meaning that critical habitats, and indeed, entire biospheres had disappeared before the KT boundary. • JD Archibald, has pointed out that 75% of our knowledge of dinosaurs immediately before the KT boundary comes from within the Western Interior of North America. (Archibald, 1997)

  13. The Laramide Orogeny • The Laramide Orogeny, or uplifting of the Rocky Mountains, began within the interior of the continent at ~80 mya and lasted until ~50 mya. • However, many major thrusting events occurred directly at the 65 my boundary.

  14. Laramide magmatic trend dated between 64 and 69 mya. (Officer and Page, 1996) • The Black Hills, along with the rest of Wyoming and Montana, weas uplifted between 72 and 58 mya. • New evidence shows that the Kaibab plateau, which was uplifted along with the rest of the larger Colorado plateau, had uplifted as early as 65 mya. (National Geographic, 2007) • Carlsbad Caverns in New Mexico was formed within the limestone of an ancient coral reef that was uplifted at the KT boundary and filled with sulfuric acid (H2O + sulfur) that ate away the limestone. The formation of the caverns themselves began ~60 mya. (National Park Service, 2006)

  15. And in Texas, we find the actual edge of the continent, or Cretaceous shelf. The Balcones Escarpment was uplifted at the KT boundary, along with the rest of western North America. • From the Balcones fault to the Gulf Coast, at least one-third of Texas sits upon Tertiary or younger sediments that were deposited as the Rocky Mountains uplifted to the west and the sediments drained into the Gulf. (Chronic, 1987)

  16. So then, I wanted to know what exactly caused the Laramide Orogeny? • The Laramide had its beginnings within the interior at ~80 mya. • This age would just happen to coincide with the formation of the Sierra Nevada batholith on the west coast, as the magma beneath this arc stopped melting and solidified into granite.

  17. Many scientists today believe that the Laramide was caused by the flat-slab subduction of the Farallon plate. However, remnants of the Farallon are still subducting beneath North America, and as far as we can tell, they are not flat. So then, what caused the slab to go flat at the KT boundary? (Oceanography, 4th ed., Garrison)

  18. One study shows that "Subduction of an oceanic plateau about 85-65 Ma (remnants in the Franciscan) produced east-vergent tectonic wedging in the Coast Ranges, possible thrusting along the eastern Sierra Nevada Batholith margin, and development of Rocky Mountain Laramide structures.  The ‘Laramide Orogeny’ is herein redefined to include all Late Cretaceous-early Tertiary (75-45 Ma) fold thrust structures from the Pacific Coast to the Rocky Mountains.“ (Moores, Wakabayashi, and Unruh, 2003)

  19. It is within the Franciscan melange that we find our clues to what really happened at the KT boundary.On the west coast of North America, we can still see the scar.(Scripps Institute of Oceanography)

  20. The Coast Range Ophiolite represents a piece of Jurassic age oceanic crust that was uplifted onto the North American continent. The Great Valley Sequence represents the sediments that were deposited on that ocean floor while it still lay within the ocean. Structurally, the Franciscan lies beneath the Coast Range Ophiolite and Great Valley Sequence in California. The Franciscan is a melange, or mixture of differing materials: greywacke, greenstone, chert, and serpentinite.

  21. USGS Professional Paper 1515, The SanAndreas Fault. Geologic sketch map of California, Based on U.S. Geological Survey (1966), Jennings and others (1970), and Ross (1984).

  22. Greywacke One study shows that one sandstone sequence found within the Franciscan is volcanic in nature and “concluded that these rocks were deposited on the flank of an oceanic rise or plateau….” This study also showed that the sandstone is similar in chemistry to the Greenstones found in the Permanente terrane of California. (Larue and Sampayo, 1990)

  23. Greenstone The Greenstone found within the Franciscan is…”an altered oceanic pillow basalt believed to have been formed during the Jurassic and Cretaceous far out in the Pacific along a spreading oceanic ridge.” (Mount Diablo Interpretive Association)

  24. Manganiferous Cherts • One study shows that the cherts found within the Franciscan are manganiferous, and were also formed on the flanks of a mid-ocean ridge. (Crerar, 1982) • Manganese is known to emanate from hydrothermal vents along mid-ocean ridges today.

  25. The Caleras limestone “Jenkyns 1980), Sliter (1984), and Tarduno, et al., argues that the Caleras limestone was deposited on top of an oceanic rise or plateau during the Late Cretaceous and was subsequently transported NE until it was accreted to the North American continental margin about 65 mya.” (in Larue and Sampayo, 1990)

  26. One study shows that a Jurassic age hydrothermal vent community has been found within the Franciscan, similar to those found around the Galapagos Islands today. (Little, Danelian, Herrington and Haymon, 2004)

  27. The Franciscan, then, would seem to show all of the evidences of being a mid-ocean ridge AND associated ocean-island plateau (hotspot), similar to today’s Galapagos Islands. • But if the Franciscan does indeed represent an oceanic plateau and mid-ocean ridge segment, WHEN, exactly did it subduct beneath North America?

  28. The Great Valley Sequence that lay on top of the Coast Range Ophiolite has been dated from ~140-65 mya. • Meaning that these sediments had been accumulating for ~75 my. • But by 65 mya, the GVS had been uplifted and was subject to erosion. (Mount Diablo)

  29. Major Franciscan uplift ca. 65 mya, coeval with graben formation within the CRO, at the KT Boundary (Moxon and Grahamm, 1987; Unruh, Dumitru and Sawyer, 2007) • Coast Range Thrust/Great Unconformity- 65 mya (Moores) • Franciscan cooling ages ~61 mya (Unruh, et al., 2007) • Los Angeles, Santa Barbara and Ventura all sit on top of thick Cretaceous-Tertiary sediments. (USGS Prof. Paper 1515)

  30. Wakabayashi showed that the Salinian block collided with the Franciscan ~60-50 mya. (Wakabayashi, 1988) • Vedder, Howell and McLean (1983) shows that thrusting on the Salinian occurred from 65-55 mya.

  31. As the Salinian block collided with the Franciscan, the MOR/hotspot would have been trapped within a backarc basin between the Salinian block on the west and the subduction zone/Coast Range Ophiolite/Sierra Nevada on the east. • As the hotspot/MOR moved was thrust beneath the continent, it would move in beneath the downgoing plate, thereby causing the flat-slab subduction that moved the Laramide into the Interior.

  32. This event is what caused the Coast Range Thrust on the west coast, the uplifting of the western half of North America continent, as well as the disappearance of the Western Interior Seaway, at the Cretaceous-Tertiary boundary.The current presentation will suggest that this event also caused the deposition of the KT boundary layer, as well as the extinction of the dinosaurs, 65 mya.

  33. All of the materials being used to describe the asteroid, can also be explained by the closing off of a mid-ocean ridge and/or ocean island hotspot. • Iridium • Glass spherules • Shocked quartz • Granite • Andesite

  34. Iridium • Member of the platinum group with platinum, osmium and rhenium • Denser than iron or nickel, therefore, would sink to the bottom of the mantle (ie.mantle/core boundary) • Brought to the surface by certain types of volcanic eruptions (mantle plumes)

  35. One study shows that rare OsIrRu minerals have been found uplifted in the Josephine Ophiolite of Oregon and northern California. • The authors of this study show that “…an ancient platinum group element reservoir with a supra-chondritic Pt/Os… exists within the mantle. (Meibom and Frei, 2002). And also, that the rare OsIrRu grains were “…transported from the core-mantle boundary region to the lithosphere as xenoliths in a mantle plume/convection system.” (Bird, Meibom, and Frei, and Nagler, 2002) The Josephine ophiolite is related to the Coast Range Ophiolite, and was uplifted along with it at the KT boundary.

  36. Glass Spherules • Glass spherules can also be created by volcanic processes as magma comes into contact with water. The magma cools rapidly on contact, creating the spherules. The ocean floors surrounding seamounts are often littered with glass spherules. • Within the Franciscan, the Stonyford volcanic complex is an ancient seamount that was accreted onto California. It is surrounded by glass spherules.

  37. One study shows that the glass spherules found within the KT boundary layer are altered oceanic basalt. This is why it is believed that the asteroid must have hit within an oceanic basin. • (Montanari, Hay, Alvarez, Alvarez, Asaro, Michel, and Smit, 1983) • This study also shows that the spheroids are K-feldspar and pyrite, which is also found on the west coast.

  38. “Shocked” quartz • Shocked quartz can also be created by geologic processes. • Also found in uplifted ophiolites. • The greywacke of the Franciscan consists of abundant angular quartz. • Deformation lamellae is present in quartz grains within the Franciscan. (Schemann, Unruh and Moores, 2008)

  39. Miller shows that at 67 mya, sea levels dropped dramatically, but that by 65 mya, sea levels had returned to near normal. • ( Miller, 2003)

  40. Between 67 and 65 mya, oxygen levels dropped from 35 parts per million to 27 ppm (Dowswell, ) • Dr. Gerta Keller showed that foraminefera began disappearing from the record 500,000 years before the KT boundary. (Keller, 2000 ) • In the oceans, high levels of CO2 cause calcium-bodied plankton to dissolve at depths of greater than 4500 ft below sea level. • This could show that CO2 was increasing in the ocean waters at the same time that oxygen levels were decreasing in the atmosphere, before the KT boundary.

  41. The Real Killer? • Zoller studied the fine particle emissions of the Kilauea eruption of 1983 and found high levels of Iridium, as well as high levels of selenium, arsenic, and fluoride. The presence of fluoride lead these authors to believe that the Iridium was released as Iridium hexafluoride. (Zoller, 1983) • The high levels of selenium could provide a clue as high levels of selenium have also been found in dinosaur eggshells at the KT boundary.

  42. If the iridium was separated from the hexafluoride…….Hexafluoride combines with Selenium to become a poisonous gas, Selenium hexafluoride; which causes severe skin irritation, breathing difficulties and respiratory failure leading to death. • Dinosaur skeletons have been found at the KT boundary with arched backs as if they were convulsing from poisoning or asphyxiation.

  43. High levels of selenium are still found today in KT boundary soils. • This map shows where seleniferous plants in North America today are still causing trouble for cattle and other wildlife. • Open dots-50-500 ppm selenium • Black dots-more than 500 ppm selenium • (Rosenfeld and Beath, 1964, In Officer and Page, 1996.)

  44. Chixculub crater • Dr. Charles Officer, along with many others, spent years trying to prove that the Chixculub crater was a volcanic structure. • I will not argue here whether the Chixculub represents an asteroid crater or not.

  45. But, IF an asteroid did strike the Gulf at 65 mya, it did NOT cause : • the uplifting of the entire ocean floor on the west coast, • the uplifting of the western half of the North American continent; • the disappearance of the Western Interior Seaway; • the change in oxygen/CO2 levels; • the drop in sea levels; • the volcanism that was occurring throughout the world at that time; • OR the Extinctions that were already occurring hundreds of thousands of years before it hit.

  46. The evidence presented herein will hopefully show that it was the subduction of a mid-ocean ridge and ocean island plateau on the west coast of North America that DID, 65 million years ago.

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