What Are The Major Global Events Occurred During The Proterozoic?

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1. a) What are the major global events that occurred in the Proterozoic? (3)

Three global events occurred during the Proterozoic: The oxygen revolution: During the Proterozoic, biotic system were being established, which gave rise to biomass of the prokaryotic organisms like the “benthic and planktonic photosynthesizing organisms” Due to the vast developing diversity of environment, organisms could well adapt to these various environments, which increased the input of oxygen on Earth. Hence, in order for the oxygen to be accumulated in the atmosphere, Iron and Sulfur like oxygen-sinks had to be depleted.

Neoproterozoic ice ages: During these ice ages, two major glaciers were formed. One of which was formed before 600 Ma, and the
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When oxygen and nitrogen combine in water, it forms nitrate, which is an essential chemical for eukaryotic algae; however, cyanobacteria do not need nitrate for their survival, contrary, they use elemental nitrogen. This way, even after the evolution of true algae, even though in fewer quantity, cyanobacteria remained widespread, and oxygen was accumulated.

c) How do geologists know that the glaciation was widespread early in the
Proterozoic? (2)

Glaciation that are widespread can be identified based on the subglacial tillite, which is a thick layer of sediments that settle down beneath glaciers or ice caps. On top of this subglacial tillite layer is deposited marine carbonate, also known as cap carbonate. Based on their paleolatitude designated by glacial sediments’ paleomagnetism, it can be determined that these deposits are from equator region. The interaction between two types of sediments, marine (like carbonate) and subgacially deposited sediments, indicate that the glaciers had approached marine coastlines.

2. a) What reasons are there for the Wopmay orogen being referred to as a
“modern-style” orogen? (4)

It is said during the Archean period, the temperature of Earth was higher than compared to during the Wopmay orogen tectonism. This was the case because of the heavy, widespread and firm crust of the Earth. Likewise the Cordillera found in modern day west part of Canada, orogeny has three structurally

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