M_W_Chapter_21-3_End_Paleozoic_extinctions_short_version

M_W_Chapter_21-3_End_Paleozoic_extinctions_short_version -...

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End Paleozoic Mass Extinction Greatest extinction episode in the history of life, 250 million years ago What caused it??? “Extinction: How Life on Earth Nearly Ended 250 Million Years Ago” Douglas H. Erwin (2005) “Catastrophes and Lesser Calamities: The Causes of Mass Extinctions” Tony Hallam (2004)
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IMPACT? Similar to end of Cretaceous (dinosaur extinction event, called KT event)? Possible impact craters in western Australia, one on land one on the continental shelf. Exact ages not clear yet. No good evidence in the rocks for the effects of an impact, unlike the KT event
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Impact Events – clues to look for Iridium anomalies Tsunami deposits Breccias (bottom right) Shatter cones (to right) Shocked quartz (below)
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Volcanism Siberia volcanics buried an area the size of the United States in about 1 million years with 4 million cubic km of flood basalts, up to 6,000 m thick clouds of volcanic dust, acid rain etc.
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Pangaea Assembled by late Permian, then started
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This note was uploaded on 05/18/2011 for the course GEOL 106 taught by Professor Richter during the Spring '08 term at University of Louisiana at Lafayette.

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M_W_Chapter_21-3_End_Paleozoic_extinctions_short_version -...

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