Extinction: the great dying at the permo-triassic boundary Flashcards
Carbon cycle during the Carboniferous Period (“Age of Coal”)
- Ocean surface and atmosphere exchange gases and CO2 a lot
- Plants take up atmospheric CO2
- Most plants get buried (CO2 gets preserved)
Relation between Organic C burial (Coal Swamps) & Atmospheric CO2
- Reduces oxidation of organic carbon and return flux CO2 to the atmosphere
- Reduces greenhouse gas warming and temperatures drop
13C/12C ratio: positive vs negative
- If this ratio is positive (or over 0), then that means it is enriched in 13C (like in the oceans).
- If the ratio is negative, then it is 13C depleted (like in photosynthesis)
What is fossil evidence for the assembly of Gondwanaland?
- Glossopteris fossils (tongue-like leaves) and other fossils found on all continents suggest that they were once connected in a huge land mass (Gondwanaland)
- Gondwana rocks also suggest this
frctionation
preferential uptake of lighter isotope by nature: in the 13C/12C ratio both organic matter and coal are depleted in the heavy isotope 13C
background extiction
typical process of turnover and replacement
how is a mass extinction defined?
Magnitude: very great (many families going extinct)
Duration: somewhat brief (a few million years or less)
Influence: occurred globally
Main victims of the “Great Dying” at the end of the Paleozoic Era (i.e. Permo-Triassic Boundary, PTB)
Lots of marine invertebrates
Trilobites
Articulate brachiopods
Tabulate and Rugose Corals (two major coral groups)
Sea scorpions
Therapsids were hit very hard, but still managed to hang on
What geological evidence is there for ice sheets on Gondwanaland
Glacial fülliges of Carboniferous age Rest non-confomably atop crystalline basement rocks of all five stratigraphic sections
When did the great dying happen?
At the end of the Paleozoic era
