Permian mass extinction in a nutshell

Based on the knowledge acquired from discovery channel, do enlighten me if you happen to know some specific details which I left out. 


Trigger: Volcanic eruptions(Siberian Traps) lasting for up to a million years causing large amounts of sulfur dioxide and carbon dioxide to be released.
Direct consequence: Sulfur dioxide would have caused acid rain that damages the eco system, but the damage would not have been so extensive.
The carbon dioxide released in such enormous quantities would cause severe global warming that kills off 1/3 of land dwellers at that time.
Indirect consequence:The heated planet with its warmer oceans would devastate the 'conveyor belt' preventing proper circulation of oxygen in the ocean. With the absence of oxygen in the ocean marine aerobic life would die out. It also causes purple sulfur bacteria to thrive. Which is, bacteria that survives without oxygen. In addition, these bacteria produces highly toxic hydrogen sulfide which adds on to the devastation done on the marine life of the Permian period.  
The heated ocean would also cause highly temperature sensitive methane hydrate, combination of methane and water in its solid form frozen at the bottom of the ocean, to melt releasing methane which is a very potent green house gas. It further aggravates the problem of global warming increasing Earth's temperature even further and wiping out even more life on Earth in the Permian period.
Ps: I will be writing a few posts about the conveyor belt and methane hydrate really soon to further explain how it plays a role in the Permian mass extinction!      

Great oxygenation event

Disclaimer: The stuff I share is from what I've read and learned. It may be extremely vague. I only hope to present the things I learned in a more simple manner for understanding.(if it even helps) and maybe to discuss. 


The great oxygenation event is the point where oxygen became a permanent part of our atmosphere that happened about 2.4billion years ago. Before that, oxygen is produced by photosynthesis, but quickly combines with elements (such as iron), and organic matter and does not stay in the atmosphere. The great oxygenation event happened when there are not enough of those reactants on the surface to react with the oxygen since they were already reacted to form compounds. This cause oxygen to remain in the atmosphere and accumulate over time.
Oxygen is produced by cyanobacteria which can carry out photosynthesis. The word 'cyano' refers to the colour of the bacteria, which is actually blue-green algae.
Note: Another reason for the fact that oxygen did not immediately accumulate in the atmosphere is that it reacted with methane first, which was present due to other bacteria at that time, to give carbon dioxide.