Jurassic Park Period Part 1

 

Paleogeography

Everybody knows about dinosaurs, right? And thanks to the Jurassic Park series of movies, we all know the dinosaurs lived during the Jurassic Period. But what else is noteworthy about this geologic period? I'll try to uncover something other than various dinosaurs to study.

However, I am just as fascinated with dinosaurs as any little kid, so I'll spend some time studying some of our favorites while I'm at it.

The Jurassic Period started 201.3 million years ago and ended approximately 145 million years ago. There was, as seems so common with these geological periods, an extinction event at the dividing point between the Triassic and Jurassic Periods.

The Triassic/Jurassic extinction event seemed to be caused by the Central Atlantic Magmatic Province, which, as best I can figure out, means a lot of magma and lava was moving around in the areas currently known as northwestern Africa, southwestern Europe, southeastern North America and Northeastern South America.

The articles I read seemed to indicate that this was not just a matter of volcanic activity, that some of it could have been caused by the action of diverging plate tectonics. We are aware of the Atlantic rift, where two tectonic plates are moving away from each, allowing a large volume of magma to flow, but this is not considered a volcano. This magma movement began about 201 million years ago, and continued for about 600,000 years. It was the largest activity of this type known to man, covering roughly 11 million km².

By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses: Laurasia to the north and Gondwana to the south. The rifting between North America and Africa was the first to happen, in conjunction with the Central Atlantic Magmatic Province

By the beginning of the Jurassic, there was flooding in most parts of central and western Europe, transforming it into an archipelago of islands surrounded by shallow sea. Beginning in the Early Jurassic, the proto-Atlantic was expanded by the "Viking Corridor" (or Transcontinental Laurasian Seaway) which stretched between the Baltic Shield and Greenland, and was several hundred kilometers wide. All during the Jurassic, the North Atlantic Ocean remained relatively narrow, while the South Atlantic did not open until later.

At the beginning of the Jurassic, North and South America remained connected, but at some point, they rifted apart to form the Caribbean Seaway, which connected the north Atlantic Ocean with what is now called the Pacific Ocean, although it was much larger back then, taking up over half the globe and was called the Panthalass Ocean.

About 183 million year ago, another magmatic event started, the Karoo-Ferrar event, this one in South Africa and Antarctica. This triggered another extinction event by causing widespread oceanic anoxia, ocean acidification and elevated temperatures. I am uncertain if these types of conditions were responsible for the Triassic/Jurassic extinction event.

Madagascar and Antarctica rifted away from Africa in association with the eruption of the Karoo-Ferrar large igneous provinces, which opened the western Indian Ocean and began the fragmentation of Gondwana.

During the Middle to Late Jurassic, the Sundance Seaway, a shallow inland sea, covered much of northwest North America.

The sea level rose and fell many times during the Jurassic, peaking at one point as high as 140 meters (462 feet) above the present level.

Wow! So much happening! And that's just the geography! This makes me wonder what else was going on!

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

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

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

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

Ur...

Okay, not a lot of information on this subject. Only to be expected, I suppose, since Ur is the name given to the very first super continent, which came into being about 3.1 billion years ago. At that time, the only life on Earth was single-celled, and some of it knew how to photosynthesize. And it’s called a super continent, though it was probably smaller than modern Australia.

It qualifies as a super continent because it incorporated all or nearly all pieces of land then in existence. More recently, scientists have started calling Ur and other small ‘super’ continents by the term super-cratons. The best I can figure is that a craton is a piece of land considered too small to be a continent.

Other scientists have postulated the existence of another super-craton at about the same time, which they have called Vaalbara, but apparently, the ideas of these two early cratonic assemblages are incompatible.

About 1,300–1,071 million years ago, Ur joined the continents Nena and Atlantica to form the supercontinent Rodinia. In one proposal, Ur remained the nucleus of East Gondwana until that supercontinent broke up. But in other proposals, India and East Antarctica did not collide until Rodinia formed 1,071 Million years ago. However, during that time period, the Earth’s mantle was 200 degrees C hotter than today, making many characteristics of modern tectonics rare or non-existent. This would preclude Roger’s 3 billion years ago supercontinent of Ur.

The proposal for the super-craton Vaalbara places two cratons, Kaapvall of southern Africa and Pilbara of western Australia, next to each other based on stratigraphic similarities. In Roger’s configuration of Ur, these two cratons were placed far apart during Gondwana, which is contradicted by widespread collisional events between Australia and Africa.

Yet another possible supercraton, Zimgarn, was proposed by Smirnov in 2013. Unfortunately, I didn’t understand the paragraph dealing with it, so I’m mostly ignoring it. After all, I’m supposed to be studying Ur.

Geological similarities in parts of India (Singhbhum and Dharwar), western Australia (Kilbaran and Pilbara), and southern Africa (Kaapvall and Zimbabwe) indicate these area were close together in the Mid-Archaean Era. Ur was named for the german prefix meaning “original” by Rogers because in his proposal, it was the first continent. Other Archaean continental assemblages are considerably younger. In some reconstructions, the various pieces of Ur stayed near each other until the break-up of Gondwana.

So, was there really an Ur, as proposed by Rogers? Should it really be called Vaalbara or Zimgarn? Or something else entirely? I didn’t find any indication of where it was located, and given how long it supposedly existed, it could have drifted quite a ways from its original location, but still, I would have liked to see some of that type of information.

How many planets do you suppose are out there with only single-celled life and 1 large island? With such a small land mass, would it be worth it to colonize it?

 

https://en.wikipedia.org/wiki/Ur_(continent)

https://simple.wikipedia.org/wiki/Ur_(supercontinent)

Hadean Eon

Unless you have a degree in geology or paleontology or something similar, you are probably as confused by the various Ages, Eons and Periods that get named when you look anything up about the History of Earth. I decided to take a look at one of them, and see if I could get it figured out as to when it happened, what major events happened during it... that sort of thing.

So, I had a list of these names, and I picked one at random: the Hadean Eon.

Turns out, I had picked the very first of Earth’s Eons; it started with the formation of Earth about 4.6 billion years ago and ended approximately 4 billion years ago. Other names for it are the Priscoan Period and the Pre-Archean Eon.

Obviously, since we are looking at the very first half billion years of the world, we won’t be talking about dinosaurs or super continents. What could there possibly be to discuss? Well, let’s dig in and see what turns up.

First, there’s the name, which gives us a clue about what was going on. ‘Hadean’ comes from Hades, the Greek god of the underworld. And that describes the conditions of what Earth was going through: The planet had just formed and it was very hot due to a number of factors, including frequent collisions with other Solar System bodies.

One important collision happened about 4.5 billion years ago, when a Mars-sized planetoid smashed into the infant Earth. The collision sent quite a lot of material into orbit around Earth, while the planetoid and the rest of Earth merged and tried to settle down. The orbiting material probably took less than a century to form the moon.

The big collision didn’t melt all of the Earth, but a fair fraction of material was vaporized, which created a rock vapor atmosphere around the young planet. But that rock vapor would have condensed out within 2,000 years, and left behind an atmosphere heavy in CO2 with some hydrogen and water vapor.

Apparently, there was a sizable quantity of water in the material that formed the Earth. After the moon was formed, the surface temperature was about 230C (446F), but even so, oceans of liquid water existed. That’s because the atmospheric pressure was over 27 times what it is today, because of the heavy CO2 atmosphere. As cooling continued, most of the CO2 was removed from the atmosphere by subduction and dissolving in ocean water, but the levels oscillated wildly.

One theory posits that between 4.4 and 4.1 billion years ago, the Earth’s climate was relatively cool, allowing for liquid water to be present at least that long. It was even suggested that the Earth may have been pretty much like it is today, except for the absence of flora and fauna.

One of the articles implied that life may have been getting started by the end of the Hadean Eon. But that was almost like a throw-away at the end of the last paragraph, so I’m thinking , one celled organisms? Maybe?

So as far as stories go, what if a spaceship gets too close to a forming star system and gets clobbered by tiny planetoids until it is forced to crash land on the nearest planet, which just happens to be vaguely Earth-like, but the only life it has are some quasi-amoebas swimming in the oceans. Maybe they have plants or seeds aboard, so they can grow some food. What about the stuff they don’t realize they’re carrying? Cockroaches, mice, fungal spores... What would those things evolve into, once there was enough food on the planet for them to successfully venture off the ship? There would be a whole lot of niches in the food chain for them to fill!

https://en.wikipedia.org/wiki/Giant-impact_hypothesis

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