reply to post by ZombieJesus
there are several competeing theories about the cause of the the permian triassic event, 1) a massive release of methane into the atmosphere,2) a
massive release of CO2 into the atmosphere, 3) a massive release of hydrogen sulfide, and 4)massive vulcanism( the large igneous province eruption
that caused the siberian traps),5)an extreme acidification of the oceans by a massive release of sulfur and CO2 into the atmosphere(it caused there
to be a layer of sulfuric/carbonic acid several feet deep on the oceans surface.
There is good evidence for all of the above theories, but only one mechanism can tie all them together, a massive deep ocean impact of an extra
The planet had only one continent at the time, pangea, and it straddled the equator almost from pole to pole. This caused there to almost no
east-west mixing of the ocean opposite of the continental mass.
As a result of this there was a warm calm ocean, that for tens of millions of years allowed for the unrestrained growth of planktons and other
microscopic organisms in the warm upper layers of water. As they died and fell to the seafloor great layers of limestones and methane deposits
formed(in the form of methane hydrates).
Then a large comet or asteroid come along and smacks into the ocean basin, this causes a couple of things, first billions of tons of limestone are
vaporized and huge amounts of CO2 are released as are the methane deposits, that are stirred from the the whole ocean basiny by the ensuing shock
Another thing that happens is that, unlike a continental impact where most of the energy is reflected back into space by the thick rocks of a
continent, the energy is absorbed by the mantle and is transmited via seismic waves around the core and refocused to erupt out on the opposite side of
the planet as large igneous province forming mantle plume. This is what likely caused the siberian traps eruption that added even more CO2 and sulfur
and hydrogen sulfide to the atmosphere.
A good argument for such an event is supported by a USGS paper on Anti-podal hotspots.
anti podal hotspot formation
Since no ocean crust is more than 125 million years old there will be no tell tale crater for such an event, but it is the only theory which can
account for all of the varios eveidence in the permian triassic extinction, where 90% of all ocean life went extinct