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

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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 yearsuntil 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 least...

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