Saturday, November 02, 2019

Pondering the Precambrian #41


Glauconite is rare is precambrian deposits of the Bhima Basin.  Why?


There is evidence of the oxygen and other environmental conditions across the Ediacaran/Cambrian boundary from southern China.

Could the marine waters have been highly alkali at the terminal Ediacaran?

Cloudina acted as an anchor for Ediacaran reefs.

Sulfur and carbon cycles from the Ediacaran formations of the Lower Yangtze block.

Oxygen levels during the NeoProterozoic were transient.

There were two episodes of phosogenesis in the ocean water of the Doushantou formation.

The Doushantou and Datangpo formations from the Ediacaran and Cryogenian have been argued to represent evidence of photosynthetic productivity during the Snowball Earth episodes.  This is probably wrong.

There is evidence from India of biofilms from the Neoproterozoic.

The microfossils of the Katanga Supergroup are probably pseudofossils, alas.

Boxonia bearing stromatolites from Mongolia suggest variation in their formation compared to others.

Ediacaran Biota-like disc fossils have been found in the Cryogenian, 80 million years earlier than ever before.

The Cryogenian basin deposits of south China suggest massive hydrothermal activity during the Sturtian Glaciation (Snowball Earth).

What was the stratosphere of the Snowball Earth like?

The Tonian Callana Group has a carbon anomaly that does not match the one observed at Bitter Springs.


There is evidence of the breakup of the Columbia Supercontinent from Brazil.


Kimberlites from the Siderian suggest there is an isolated mantle reservoir.  And may be fingerprints of the ancient makeup of the world's geology.

There was a very long lived tectono-magmatic event 1.8 billion years ago.

The geochronology of the Hart Dolerite of Australia is documented.


There is evidence of oceanic crust subduction from the NeoArchean.

There is also evidence of mountain building from the NeoArchean.

There is evidence of a subduction/accretion/collision event at the end of the NeoArchean, confirming full blown plate tectonics were in progress at that time frame.

Mesoarchean deposits from islands suggest the pelagic environment was rich in boron.

Paleoarchean microfossils show a continuous cell wall amongst other characteristics.

Can Xenon help determine if the carbon traces in ancient rocks is biogenic or not?

The fingerprints of Ur, the earliest supercontinent, are in the Bastar Craton in India.


The energy budget and structure of the earth get modeled during and after the Thea impact.

Origin of Life:

Bacterial gene duplicates are more common in eukaryotes than expected.

Is there a relation between hydrothermal chemistry and the origin of cellular life?


Archaea's biochemistry may give hints as to ancient ocean temperature.

A large virus may have helped make the first eukaryote allow endosymbiosis allowing for the evolution of photosynthesis in eukaryotes.

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