Week 7 - K-Pg Boundary Flashcards
What were the climate trends during the Late Cretaceous (~100-66 Ma)?
Warm and wet, but slightly cooler than the mid-Cretaceous thermal maximum.
What major oceanic changes occurred during the Late Cretaceous?
The North and South Atlantic Oceans were opening, and the Tethys Ocean was slowly closing.
What continents were moving northward in the Late Cretaceous?
India and Australia.
How do we know global temperatures were higher in the Late Cretaceous?
Coniferous forests extended into polar regions.
What were the climate trends in the Early Paleogene (~66-56 Ma)?
Climate remained warm but showed cooling trends.
What was the Early Eocene Climatic Optimum (EECO)?
A warm period occurring around 53-50 Ma.
What percentage of species and genera went extinct during the K-Pg mass extinction?
~75% of species, ~30% of genera.
What ecosystems were affected by the K-Pg mass extinction?
Both marine and terrestrial ecosystems.
Name some major victims of the K-Pg mass extinction.
Non-avian dinosaurs, pterosaurs, mosasaurs, ammonites, belemnites, rudist bivalves.
What primary producers were heavily affected during the K-Pg mass extinction?
Planktonic foraminifera, coccolithophores, some land plants.
How did the K-Pg extinction affect the carbon cycle?
It caused major disruptions, affecting ocean chemistry and food chains.
Name some survivors of the K-Pg extinction.
Birds, small mammals, crocodiles, sea turtles, insects, worms, snails, amphibians.
What traits likely helped species survive the K-Pg extinction?
Adaptability, burrowing behavior, and detritus-based food chains.
How many global boundary sections exist for the K-Pg extinction?
About 350 sites worldwide.
Name three key lithological markers of the K-Pg boundary.
Iridium layer, shocked quartz & microtektites, boundary clay layer.
What does a high concentration of iridium at the K-Pg boundary suggest?
An asteroid impact, as iridium is rare on Earth but abundant in asteroids.
What do shocked quartz and microtektites indicate?
High-energy impact events.
What does the boundary clay layer indicate?
Sudden sedimentary change due to environmental upheaval.
Where is the Chicxulub crater located?
Yucatán Peninsula, Mexico.
How large is the Chicxulub crater?
150 km in diameter, formed by a 10 km-wide asteroid.
What key evidence supports the Chicxulub impact hypothesis?
Iridium anomaly, shocked quartz, microtektites, and ejecta layer (glass spherules).
What short-term environmental consequence followed the impact?
“Impact winter” caused by dust blocking sunlight.
What long-term effects did the Chicxulub impact have on the climate?
Increased CO₂ and sulfur emissions led to acid rain and ocean acidification.
How did global wildfires contribute to climate change after the impact?
They released massive amounts of CO₂, worsening climate effects.
