Orosirian & Statherian Periods

 Orosirian Period

The 3rd geologic period in the Paleoproterozoic Era is the Orosirian Period, which loosely means ‘mountain range’. This period lasted from 2,050 to 1,800 million years ago.

The latter half of the period involved intense orogeny on virtually all continents. Orogeny is when 2 continental plates slam into each other and one is shoved down, while the other is shoved up, producing mountain ranges.

Other important events include 2 of the largest known impact events. At about 2,023 million years ago, a large asteroid collision created the Vredefort impact structure, located in what is now South Africa. Although most of the crater has eroded away, the impact dome at the center is still visible.

Towards the end of the period, about 1,850 million years ago, the Sudbury Basin was created by the impact of another asteroid in what is now Ontario Canada. I’m not sure if the article was saying the basin is in the city of Greater Sudbury, or the city is in the basin. It did state that the locals merely refer to it as ‘the valley’.

So, the Orosirian Period saw much happening to Earth’s crust, from holes being punched into it (craters) to mountains climbing towards the sky. I couldn’t find anything on life forms or what the environment was like, which is a bummer. I assume the lifeforms that existed at the beginning of this period mostly managed to survive, and possibly evolved.

 

Statherian Period

The final period in the Paleoproterozoic Era is the Stratherian Period, which roughly means ‘stable, firm’. It started at 1,800 million years ago and lasted to 1,600 million years ago.

This period was characterized by erosion and folding. Folding, as I understood the article was when the forces that created mountain ranges continued to deform the land around the mountains, forming foothills. In other places, erosion took place, sending sediment to a lower level, which formed new platforms of land extending out from what land already existed.

The oldest known eukaryotic fossil organism was found in Statherian beds in India, so life was carrying on. At that time, the oxygen level was 10-20% of our current level.

By the beginning of the Statherian Period, the supercontinent Columbia had assembled.

So there we have all the important highlights of the back half of the Paleoproterozoid Era. It almost sound like a livable place. Well, except the oxygen level would be a problem. And I’m not sure we have any earthworms yet to help fertilize the soil. Well, at least we’re getting closer to a livable planet!

 

https://en.wikipedia.org/wiki/Orosirian#:~:text=The%20Orosirian%20Period%20(%20%2F%CB%8C%C9%92r,these%20dates%20are%20defined%20chronometrically.

https://en.wikipedia.org/wiki/Vredefort_crater

https://en.wikipedia.org/wiki/Sudbury_Basin

https://en.wikipedia.org/wiki/Statherian

https://en.wikipedia.org/wiki/Craton

https://en.wikipedia.org/wiki/Fold_and_thrust_belt

Siderian & Rhyacian Periods

 

Siderian Period

There are 4 periods in the Paleoproterozoic Era, the first being the Siderian Period. This period lasted from 2,500 to 2,300 million years ago.

Early in this period is when banded iron formations peaked. As I explained before, cyanobacteria produced waste oxygen, which initially combined with iron that was in the sea, forming magnetite (Fe3O4), an iron oxide, in a crystal structure rock. This process removed iron from the oceans, presumably turning the greenish water clear.

Then, with no remaining iron in the sea to serve as an oxygen sink, the oxygen escaped the ocean and built up the oxygen level in the atmosphere. This led to the oxygen catastrophe, wherein a great deal of the life then existing on the Earth was wiped out because they could not tolerate such high levels of oxygen.

Some geologists believe the high level of oxygen also triggered the Huronian glaciation. This glaciation started in mid-Siderian (2,400 million years ago) and extended into the next period, lasting until 2,100 million years ago. It was apparently caused when free oxygen combined with the methane in the atmosphere to form carbon dioxide and water, which do not retain heat as well as methane does. With far less of this greenhouse gas in the atmosphere, a great chilling took place, also known as the Huronian glaciation. I don’t know if the entire planet froze, and the article stated that this glaciation caused a mass extinction. I’m waiting for a geologist I know to clarify whether there were 2 mass extinctions so close together, or just one, with both the presence of oxygen and the cooling temperatures to blame.

 

Rhyacian Period

The Rhyacian Period is the 2nd geologic period in the Paleoproterozoic era. It lasted from 2,300 to 2,050 million years ago. And that is just about all the wikipedia article had to say on the subject. Oh, there were a bunch of rock formations created, and the Huronian glaciation lasted 100 million years, but that still leaves 150 million years at the end of the period during which, apparently, absolutely nothing of note happened.

Oof! What was the tipping point that caused the end of the glaciation? For that matter, did it cover the entire Earth? Was there an explosion of new species afterwards?

Maybe they don’t know. What about theories? Doesn’t anybody have any theories? Well, without sitting my geologist friend down and picking his brain clean, I guess that’s as far as I can go with this period. Maybe the next 2 period of the Paleoproterozoic Era will have more meat to them.

 

https://en.wikipedia.org/wiki/Siderian#:~:text=The%20Siderian%20Period%20(%20%2Fsa%C9%AA,these%20dates%20are%20defined%20chronometrically.

https://en.wikipedia.org/wiki/Rhyacian