Lecture7 Flashcards
ancient Climates
___ conditions dominate, ____ conditions punctuate
greenhouse, icehouse
Quaternary is the _____ since the Permian
first well defined icehouse
6 major glaciations
midarchean, huronian, proterozoic, late ordovician, permo-carboniferous, pleistocene
evidence of glaciers
till, diamictite, dropstones, striations
Huronian Glaciation
2.4 Ga
- coincided with great oxidation event, lots of photosynthesis and methane oxidation
- redbeds are evidence of it
proterozoic glaciations
0.75-0.6 Ga
- glacial deposits around world from ediacaran time, paleomagnetic data supports
- changes in plate tectonics, oxygenation and carbon cycling
How to end a snowball earth
volcanoes, keep pumping out co2 until overpowers albedo feedback
survival on snowball earth
slushball, refugia, clear thin ice, biotic fractionation
when did the nucleus come to be
after the Huronian snowball
mid-ordovician cause
drop in CO2 levels, sequestration?
Paleocene Eocene Thermal Maximum (PETM)
55.8 ma
- proto-Atlantic widening
- north sea opening
- no ice at poles
- warm
PETM defined by
- negative 13C excursions (carbon isotopes get light)
- global temp increase according to oxygen isotopes
- quick initial warming, short lasting
on land evidence of petm
- pedogenic carbonate
- organic carbon
- leaf wax
- isotopic excursion in mammal teeth
- fossils are getting smaller
at sea evidence of petm
- major ocean acidification
- carbon accumulation
- shoaling (shallowing) of CCD
- new species
- extinction for foraminifera
Large Igneous Provinces
Super big areas of volcanism
- flood basalts, rifts, oceanic plateaus, ocean basin flood basalts
- punctuate most mass extinctions
