Saturday, February 02, 2019

Pondering the Precambrian #26



The Earth's magnetic field was 10% of what it is today during the Ediacaran and the Earth's solid core may date from that period.

Evidence from Murmansk supports the weak magnetic field hypothesis during the Proterozoic.

Trace fossils from the Ediacaran have been found in Brittany, France.

Ediacaran environmental changes are recorded in Brazil.

The iodine content of the the Doushanto deposits of the Ediacaran.

Microorganisms are the source of organic carbon found in Sichuan from the Ediacaran into the Cambrian. 

It appears Cloudina and other tubular organisms from the terminal Ediacaran appear to have reproduced asexually.

There is evidence of hydrothermal activity altering various deposits during the Ediacaran.

Evidence of the breakup of Rodinia to the accretion of Gondwana in the Ediacaran from Paraguay.

A new biomarker has been found from the Cryogenian that hints at how complex life evolved after the Snowball Earth.

There was a deep marine organic reservoir in the Cryogenian.

Starting in the Cryogenian until the start of the Carboniferous, there was significant lack of impacts.  There might be evidence of the Snowball Earth via a global wiping of the impact craters from before that point, too.

Could the Great Noncomformity be due to the Snowball Earth?

The Great Noncomformity represents a 200to 300 million year gap in the depositional history of the world according to evidence from the North China Craton.

There are graphite particles in Cryogenian deposits of Nantuo.

Manganese ore deposits in South China were formed in the interglacial between the Sturtian and Marinoan glacials by microbial activity.

Is hydrothermal activity from the Tonian of the Western Australian Craton evidence of the breakup of Rodinia?


Eukaryotes diversified earlier than previously thought, starting in the Ectasian.


There was a 30 degree shift in the mafic dyke swarms during the Paleoproterozoic.

The surface conditions of at the start of the Great Oxygenation Event were anoxic.

There is evidence from the Yangtze Block that contradicts the hypothesis that there was a shutdown of plate tectonics during the PaleoProterozoic.


A coupled crust/mantle formed before 2.5 billion years ago.

Evidence from the MesoArchean to the Paleoproterozoic of Norway show how the continents were built up.

More evidence of episodic crust growth starting in the MesoArchean.

There may be EoArchean deposits in the North China craton.

Sarmatia, Pilbara, and Kaapvaal Cratons were all part of the single supercontinent Vaalbara.

There's no evidence of pre 3.95 billion year old fossils.


Did the impact with Theia provide the volatiles the Earth needed for life?

Did asteroid impacts have a central role in the formation of the original continents?


There is a 600 million year superocean cycle modulating a longer supercontinent.

Could sulfur dioxide have helped with the start of prebiotic carbohydrates?

There are biochemical hints that the last common universal ancestor - the last life form from which everything alive is descended - was not a hyperthermophile.

Reconstruction the Last Eukaryote Common Ancestor's genome to understand the evolution from the First Eukaryote Common Ancestor to the LECA.

Chunks of RNA can be formed prebioticly.

Studying algae suggest eukaryotes have received numerous DNA additions from bacteria.

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