EX L2: K/Pg Event Flashcards
What new era arrived at end of Permian extinction?
Mesozoic era
What extinction marked the beginning of the Cenozoic era?
The end of the Cretaceous extinction
After what extinction did Mesozoic era arrive?
End of Permian extinction
What is the latest grouping of periods?
Cenozoic
What percentage of species would go extinct during the K/Pg (Cretaceous-Paleogene) extinction event?
Over 50%.
On land, most creatures over 25kg died.
In ocean, 80-90% of marine species went extinct.
Was the K/Pg extinction event harsher for land or marine creatures?
Marine. 80-90% went extinct, including ammonites and marine reptiles.
Which extinction event is known for the death of the dinosaurs?
The K/Pg extinction event.
Which extinction event is known for its association with a major extra-terrestrial impact event?
The K/Pg extinction event.
Who first brought the possibility of an extra-terrestrial impact to be the cause of the K/Pg extinction?
The father and son scientific team, Louis and Walter Alvarez.
How did Louis and Walter Alvarez bring up the idea that a space object hit Earth and during the K/Pg?
They were investigating a clay layer in a geological section that crossed the K/Pg boundary in Gubbio, Italy. The 1-cm layer was directly on top of the latest Cretaceous rocks, and was found to be enriched in the element iridium
Where is Iridium known to exist in higher concentrations?
Asteroids.
What did Alvarez suggest about the clay layer enriched in iridium?
It was produced by a meteor or comet over 10 km in diameter that impacted the Earth. This impact may have been responsible for the extinction at end of Cretaceous period.
How big is the extra-terrestrial object that hit Earth suggested to be?
Over 10 km in diameter.
Name the four points of evidence that support the impact of a meteor or comet being the cause of the K/Pg extinction event.
- Fern spores vs. pollen.
- Tektites
- Shocked Quartz
- Tsunami deposits
Which period showed an increase in fern spores relative to pollen?
earliest Paleogene
Why are ferns a supporting factor in the idea that an outer space impact caused the K/Pg extinction?
Fern spores vs. pollen:
Ferns usually first to colonize landscape devastated by fire. Early Paleogene has more fern spores than pollen, suggesting global forest fires raged at end of Cretaceous, leaving landscape open for ferns to spread. Further supported by high concentrations of soot found around K/Pg boundary.
Why are tektites a supporting factor in the idea that an outer space impact caused the K/Pg extinction?
Tektites are composed of natural glass, produced by melting rocks during an impact event. During impact, rock is melted and ejected from crater. Traveling through air, it forms aerodynamic shapes. Many tektites are found at the K/Pg boundary in different locations, suggested the massive impact.
Why are shocked quartz a supporting factor in the idea that an outer space impact caused the K/Pg extinction?
In many sections around K/Pg boundary, fragments of mineral quartz show evidence of multiple fractures. Fractures thought to be produced when rock is shattered during high-energy impact. Fragments called shocked quartz.
What is shocked quartz?
Fragments of fractured quartz; Quartz deformed along planes called shock lamellae
What causes shocked quartz?
They’re thought to be produced when rock is shattered during high-energy impact.
Why are tsunami deposits a supporting factor in the idea that an outer space impact caused the K/Pg extinction?
Tsunami waves leave characteristic sedimentary deposits on inundated shores and as far inland as the waves reach. This was found in Mexico, Texas, New Jersey, and the Carolinas, which suggested the passage of a wave far larger than standard tectonic processes could produce. This wave could have been generated if an impact had occurred in the ocean.
Where were tsunami wave deposits found?
Mexico, Texas, New Jersey, the Carolinas.
What are some suggestions for why the crater that struck Earth at end of Cretaceous period was removed?
Removed by processes including erosion or even subduction (if impact occurred on oceanic crust).
Where is a possible space impact site?
Yucatan Peninsula of Mexico. Oil company drilled wells and encountered unusual fractured and even melted rock, suggesting area had been subjected to some form of extreme stress. Crater confirmed by geophysical data: it is over 180 km in diameter.
What is the Chicxulub Impact Crater? How did they confirm that there is a crater?
The Chicxulub Impact Crater is a large circular disturbance over 180 km in diameter, confirmed by geophysical data.
How wide is the Chicxulub Impact Crater? How big is the object responsible for the crater?
The crater is over 180 km in diameter. The object responsible for the crater is at least 10 km wide (imagine Mt Everest hitting surface of planet).
How much rock was vaporized and released to the atmosphere by the object that caused the Chicxulub Impact Crater? At what angle did the object hit the Earth? What happened to the ejecta (material not instantly vaporized)? Where is it found?
Around 100 km^3 rock vaporized and released to atmosphere.
Material not instantly vaporized was thrown out of crater (the ejecta) and deposited to the NW of the impact site.
What were the initial effects (seconds to days) of the Chicxulub Impact in the area of the Yucatan Peninsula?
1) Everything close by would have been vaporized.
2) The intense heat from the blast and the hot debris (including tektites) would have started massive forest fires (as suggested by fern and pollen data).
3) As the impact occurred partly in the ocean, a massive tsunami would have been generated.
How is global temperature change a long-term effect of the Chicxulub Impact?
1) Global temperature changes: Dust thrown into atmosphere would have shut off sunlight for weeks or months, generating a period of cold. Lack of sunlight would’ve been severe for plants and photosynthetic algae.
After dust settled, water vapour would’ve remained in atmosphere like a blanket, preventing heat from escaping Earth. This would’ve created a greenhouse effect and caused global temperature rise.
Eventually, excess water would be removed by rainfall, but temperature of Earth would continue rising due to greenhouse gases released during the impact lasting years to decades. CO2 would’ve been liberated when large quantities of limestone (CaCO3) would have vaporized during impact.
What is a “Cold House”?
Globally cold climatic conditions.
What’s a “Hot House”?
Globally warm climatic conditions
Large quantities of ______ would have been vaporized during the Chicxulub Impact, releasing carbon dioxide.
Limestone (aka Calcium carbonate or
CaCO3)
Why did the temperature continue rising even after the dust layer settle after the Impact?
Greenhouse gases were also released, and this made Earth’s temperature rise globally.
The ______ era had generally been a warm equable (fair) environment. Temperature swings would have placed a lot of stress on creatures accustomed to stable climactic conditions.
Mesozoic
How is acid rain a long-term effect of the Chicxulub Impact?
Nitric acid formed when oxides of nitrogen dissolved in rainfall.
High-energy blasts can cause what?
They can causes oxygen to combine with nitrogen to form oxides of nitrogen. When dissolved in water (rainfall), it becomes nitric acid.
How are evaporites formed?
They’re formed when salts precipitate out of solution as the sun evaporates a body of water. (they’re rocks produced by the evaporation of standing bodies of water)
Describe the formation of evaporites in the Mediterranean Sea. Why is it important to know?
The Sea is closed off at the Strait of Gibraltar. With no input of water from the Atlantic Ocean, high rates of evaporation resulted in the Sea being converted into a vast saltpan. This also occurred in the Yucatan area.
What effect do high-energy blasts have on sulfate-rich evaporites?
The process releases large amounts of sulfur gases. The gases, when dissolved in rainwater, fall to Earth as sulfuric acid.
How did the acid rain affect the food chain after the Chicxulub Impact?
It didn’t directly affect large animals, but did affect the acidity of the soil and the surface ocean. This would have been super bad for plant life and plankton. So the effects from acid rain on the organisms that form the base of the food chain or food web had serious consequences for all creatures at higher trophic levels.
Limestone and ______ vaporized in the blast of the Chicxulub Impact
evaporite (type of rock)
When did the supercontinent Pangaea begin to fragment? What did it cause?
late Cretaceous.
it caused changes in oceanic circulation and climate
What other factor, besides the Impact and the fragmentation of the supercontinent Pangaea, would have severely affected global climate and led to K/Pg extinction?
An increase in volcanic activity, especially during the formation of the Deccan Traps in India, which were highly active during the time. They produced lots of gases that seriously affected Earth’s climate.
When did the Siberian Traps occur?
end of the Permian.
What events, altogether, led to the K/Pg mass extinction?
multiple impacts, volcanism, global climate change
What creatures were most likely to survive all the changes in the K/Pg environment?
Generalists. Did not require specific foodstuffs or particular environments to thrive. It would help if a creature were small enough to hide or burrow away from more severe environmental changes. On land, mammals were the ones that were able to adapt.
Which animal group would radiate into the Cenozoic?
Mammals.
Define ammonite
extinct group of marine creatures. related to squid and octopus
Define avian/aves
birds
Define breccia
fractured rocks
Define crater (impact)
any depression in the ground resulting from high velocity impact
Define dinosaurs
group of vertebrates common during the Mesozoic
Define food chain
feeding relationships between organisms in an ecosystem
Define geophysics
physics of geology; commonly used to study subsurface features
Define gravity survey
studying variations in Earth’s gravity to reveal subsurface features
Define gypsum
a mineral rich in sulfates; common in evaporite sequences
Define microplankton
tiny creatures floating in the water column; often the base of oceanic food chains.
Define nuclear winter
cold period after a nuclear war caused by dust/soot/smoke in atmosphere
Define photosynthesis
process by which plants use light to convert CO2 into organic compounds
Define pollen
reproductive structure in flowering plants adapted for dispersal
Define shock lamellae
stress lines in quartz crystals generated by high energy events
Define spores
reproductive structure adapted for dispersal
