Impact2s - 1 Goodbye Dino 2 • The Dinosaur Killer • At...

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Unformatted text preview: 1 Goodbye Dino 2 • The Dinosaur Killer • At least 50% of ALL species lost • On Land: nothing over 25kg survives • Note: Mesozoic “Dinosaur time” is bracketed by extinction events T2:1a 3 • Not just terrestrial species • Marine fauna suffers: ammonites / marine reptiles • 80 - 90% Marine species lost Ammonite Marine Reptiles 4 • Walter and Luis Alverez • Latest Cretaceous clay layer • Enriched in iridium Gubbio, Italy T2:1b 5 • Iridium anomaly and clay layer is global 6 • Source of such high iridium? • Comets / meteorites……. NASA Deep Impact, 2005. Comet Temple 1 7 • IMPACT SCENARIO 8 • Further Evidence…. • 1. Fern Spores vs pollen • Ferns: frst to colonize fre impacted landscape Spores act as a $ proxy % ¡or ¡orest fres A fern spore A pollen grain T2:1a 9 Just after K/T have massive spike in fern spores 10 • 2. Soot layers associated with the iridium layer • Evidence of massive global Fres 11 • 3. Tektites: • Natural Glass - produced by melting rocks during impact 12 • 4. Shocked Quartz • Another “impact” feature • “cross-hatched” lines = stress lines in the quartz crystal: Shock lamellae 13 • 5. Tasunami deposits • Evidence of almost GLOBAL Tsunami activity at end of Cretaceous. 14 • The Crater: “The Smoking Gun” • Drilling off coast of Mexico - Yucatan Peninsula - “odd” rocks: – Suevite: a breccia (fractured rock) showing evidence of melting – Completely melted rocks • Sits in core store for years……until Limestone T2:1c 15 • …..geophysics reveals a crater • 180km across…. • Chicxulub Impact Crater • Tsunami deposits, shocked quartz and tektites: thicker towards this structure Yucatan Peninsula Yacatan gravity survey 16 • Shallow entry: 20 - 30° • Impact body 10km across Chicxulub: “Tail of the Devil” 17 Ejecta Layer: Yacatan 18 20 - 30° • Most of “ejecta” towards NW • 6.2 x 10 7 Tonnes TNT • 100km 3 Rock vaporized 19 Initial Effects: Vaporizes all close by / Forest Fires / Tsunami...
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Impact2s - 1 Goodbye Dino 2 • The Dinosaur Killer • At...

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