2017 questions Flashcards
how old is the oldest ocean crust in the NW Atlantic and W Pacific?
180-200 Myr
what do plumes underneath continental crust create at the surface?
massive outpourings of lava called large igneous provinces
which is not an argument against the Gaia hyp?
organisms cannot change the composition of the atm
what is the largest reservoir of carbon?
carbonate in sedimentary rocks
what describes the earth’s oxygenation state after the origin of oxygenic photosynthesis but before the great oxidation?
reducing atm, oxygenated surface ocean, anoxic deep ocean
what is a source of evidence for the great oxidation?
the disappearance of mass independent fractionation of sulphur isotopes
when was the earth’s second oxygenation event?
600-400 Ma
where would be the safest place during a snowball earth?
a geothermal heated oasis on land
what glaciations are said to have been caused by the rise of the first non-vascular plants?
Ordovician glaciations
what ocean based mechanism counteracts declines in atm oxygen?
increased ocean anoxia promotes phosphorous recycling from ocean sediments fueling marine productivity and organic carbon burial
what do mesozoic sediments tell us about atmospheric oxygen levels?
the presence of charcoal indicates O2 >15% of the atm
how did the c cycle respond at the end cretaceous extinction?
collapse of the marine biological pump added CO2 to the atm
what is the age of the Neogene-Quaternary transition?
2.6 ma
how long does one complete eccentricity cycle take?
100,000 years
what was a major factor to the build-up of large ice sheets in the N Hemisphere that defines the quaternary likely to have been?
closure of the Isthmus of Panama
the total number of MIS stages identified in the deep ocean sediment records in the quaternary now exceeds:
100
when did H Erectus emigrate out of Africa?
1.8 Ma
what was the last glacial in Britain?
devenisian
how much lower was the temp during the LGM?
5°C
where were the youngest mammoth remains found in Britain?
Candover, Shropshire
when was the YD/Holocene transition in the Greenland ice core?
~11,700 y/a
which MIS is thought to be most comparable to the Holocene?
MIS 11
when was H. floresiensis thought to have become extinct?
~ 50,000 y/a
what is the limit of radio carbon dating?
50,000 years
what is a key forcing factor of global climate over multi-decadal timescales during the holocene?
solar variability
