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K/T Mass Extinction

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K/T Mass Extinction Death from Outer Space, Did an Asteroid Impact Wipe out the Dinosaurs? The asteroid Gaspra - 7x7x12 miles A Gallery of Asteroids Was it really an asteroid? We must have multiple working hypotheses! Dinosaurs forgot to board the Ark K/T Boundary 66 MY Age of Dinosaurs Geologic Time Scale K-T extinction record Wyoming The K/T impact clay layer, T Gubbio, Italy. Iridium anomaly first found here. K = Cretaceous K T = Tertiary Iridium anomaly in the K/T rocks at Gubbio, Italy, 20 cm in parts per billion (PPB). K/T 0 boundary 10 cm PPB 0 10 The K/T boundary in New Mexico is marked by the white claystone just above the head of the hammer. Claire Belcher, Geology Department, University of London The white claystone layer marks the K/T boundary The K/T boundary in Spain Known distribution of sites with K/T Iridium anomaly Map of major impact sites in North America The Berringer Crater in Arizona, 50,000 years old. 4000 ft across -- formed by 100 ft meteorite. Why craters are so much larger than the objects that make them. Like shooting a bullet into a soft target. The Manicougan Crater in Quebec,late Triassic in age -- 100 km diameter Gosses Bluff, Australia. Crater age is 142 Ma, but no mass extinction. A 4 km wide asteroid hit America at the end of the Eocene, 35 m.y. ago the Chicxulub Crater Late Cretaceous Paleogeography Gravity anomaly map of Yucatan area 3D representation of gravity anomaly Another representation of the gravity anomaly on the Yucatan Penninsula: the Chicxulub Crater Tektites from the asteroid impact – melted rock Enlargement of a tektite from the Atlantic sea floor Tektites from the K/T boundary in New Jersey Map showing distribution of tektites by size. Tektites are largest near Yucatan. Shocked quartz from the asteroid impact The impact: 66 MY ago The 6-mile diameter asteroid heading towards Earth, 66 MY ago The start of a bad day, 66 MY ago Velocity = 20 km/s or 40,000 mph Kinetic energy about to be converted to thermal energy Impact on the Yucatan Peninsula! The power of millions of atomic bombs The K/T impact released more energy than the World’s Nuclear Arsenal Primary Killing Mechanisms: Two Hypotheses • Infrared thermal pulse “broiled” exposed animals for several hours after the impact. • A massive dust cloud blanketed the Earth, blocking sunlight. This caused a collapse of the food chain and severe global cooling. Broiled Dinosaurs Thermal radiation 7X greater than the sun Fiery debris falls back to Earth over large areas starting forest fires Worldwide forest fires consumed about 30% of all terrestrial biomass. Blast wave and dust cloud from the impact Dust from the impact, and smoke from fires, blanketed the Earth and blocked the sunlight. Temperature anomaly map 15 days after impact Temperature Change The Yucatan, a few days after impact The crater about 1000 years after impact Looking for evidence of the Yucatan impact outside the Caribbean. The Ocean Drilling Project recovers cores off the east coast of Florida in 1997. The drilling ship can send a drill string to the ocean floor and recover core. Cores layed out on the ship Section of core with K/T boundary interval. geoweb.princeton.edu/.../massex.html Forams from the Cretaceous Forams from the Tertiary.
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