Recitation 7 Flashcards
How many mass extinction events were there in the Panerozoic era?
Five, all of which will be covered in further slides
Identify the Ordovician-Silurian mass extinction event, and which time period it took place in?
Ordovician-Silurian was the third largest mass extinction event, two peak dying times separated by thousands of years, in the Ordovician period most life occurred in the sea, so sea life was drastically reduces… approx 450-440 Ma in the Phanerozoic period
Identify the Late Devonian mass extinction event, and which time period it took place in?
The late Devonian mass extinction- 3/4 of earth species died out, may have occurred over several million years, shallow sea life was most effected, reefs did not return to normal for about 100 million years… approx 375-360 Ma during the Phanerozoic era
Identify the Permian mass extinction event, and which time period it took place in?
Permian mass extinction- ‘The Great Dying’… 96% of all species died out, all of life today came from the 4% of species that survived this… approx 250 Ma during the Phanerozoic era
Identify the Traissic- Jurasic mass extinction event, and which time period it took place in?
Traissic-Jurasic- took place in the last 18 million years of the Triassic period, in two or three die offs, climate change and flood basalt eruption, plus a asteroid were all blamed (Jesus, sounds brutal)… approx 205 Ma during the Phanerozoic era
Identify the Cretaceous-Tertiary mass extinction, and which time period it took place in?
Cretaceous-Tertiary mass extinction- ‘K/T extinction’, the death of the dinosaurs, many other organisms also died… approx 65.5 Ma during the Phanerozoic
Identify how flood basalt events are theorized to have caused extinction events
Formation of large igneous provinces by flood basalt, which resulted in (1) production of dust/ aerosols which inhibit photosynthesis (2) emit sulfur oxides- acid rain- food chain collapse (3) C02 emission leading to sustain global warming… basalt events occur in PULSES, oscillation but trending towards warming
Identify how sea level falls are theorized to have caused extinction events
Sea level falls reduce continental shelf area, which is the most productive part of the ocean. Sea level falls are probably associated with other events, such as global cooling, or the sinking of ocean ridges.
Identify how impact events are theorized to have caused mass extinction events
The impact of a large asteroid or comet could have cause food chains to collapse on land and at sea. The impacts would have emitted sulfur oxides causing acid rain, and may have cause mega tsunamis.
Identify the Methane Clathrate hypothesis
Clathrates are composites in which a lattice of one substance forms a cage around another , this occurs on continental shelves. The Clathrates quickly break up and release methane when temperatures rise quickly. Methane is a much more powerful gas then C02, so scientists hypothesis a disastrous positive feed bag loop if these start to breakup
Identify anoxic events
These occur when middle and upper layers of the ocean become totally lacking in oxygen.. the cause is controversial but their occurrence is associated with global warming and sustained massive volcanic events
Identify Hydrogen Sulfide sea emissions
Hypothesized that during the Permian- Triassic extinction, warming upset balance require for photosynthesizing plankton and deep water sulfate reducing bacteria, leading to poises levels of hydrogen sulfide, effecting land and sea animals and weakening the ozone exposing life to fatal radiation
Identify Oceanic Overturn
Occurs during a distribution in the thermo-haline circulation, which lets the more saline surface water (due to evaporation) sink straight down, bringing anoxic water to the surface, killing oxygen breathing organisms that reside in the middle and upper parts of the ocean
Identify all of the processes which are theorized to have caused mass extinction events
Sustained and significant global cooling, sustained and significant global warming, methane clathrate hypothesis, anoxic events, hydrogen sulfide emissions for the sea, oceanic overturn, a nearby supernova/ gemma ray burst, plate tectonics (disrupting ocean currents
Identify Chickxulub impact crater, and the impacts impact on climate
65.5 million years ago, asteroid 10 km in diameter, 6 mil more energy than St. Helen, 500 billion tons of debris, 300 foot tidal wave.. all this resulting in global cooling, since large quantities of dust water, and climate forcing gas would alter the climate, by blocking the sun, in addition increased sulfur minerals and acid rain would disrupt life
