During the late Proterozoic from 1000 to 542 Ma, the Earth is thought to have been frozen at least during two times: in the Sturtian (715–680 Ma) and in the Marinoan (680–635 Ma) global glaciations. Following the Marinoan Snowball Earth, large multi-cellular animals of the Ediacara fauna flourished as a prelude to the Phanerozoic world. Here we summarize the most popular models on the cause and cessation of Snowball Earth. Episodic decrease of greenhouse gas occurs through the effect of erosion and weathering promoted by either mountain building or by an increase in the coastlines during the break-up of supercontinents. Effects on the globe caused by true polar wander, eruption of voluminous flood basalts, or dramatic reduction in planetary obliquity can also lead to ice ages and mass extinction. A radically revised concept based on Earth's magnetic intensity has also been proposed, which explains the true polar wander through a quasi-polar dynamo model. The ‘switch-on’ and ‘switch-off’ of the Earth's strong dynamo can lead to the onset and disappearance of the Snowball Earth. The galactic model infers that gamma ray burst associated with starburst creates huge amounts of clouds which would cut off sun rays and freeze the Earth. The Snowball Earth event is considered to have exerted a significant control on the subsequent revolutionary changes in the evolution of life forms. Although according to the biological clock, extensive re-organisation of genome is thought to have been completed by around 900 Ma, the evolution of modern life in Cambrian occurred only after the geochemical bridge was in place with elevated oxygen and nutrient levels in lakes that developed within continental rifts where the hydrothermal system in the granitic basement created the chemical environment enriched in Ca 2+ , Fe 2+ , V, Mo, HCO 3 , phosphate and other elements required for building the skeleton and bone of the first modern animals. With cosmic radiation exerting a significant control on the mutation, the Neoproterozoic Earth history illustrates the possible link from Galaxy to the genome level.
Gondwana Research – Elsevier
Published: Aug 1, 2008
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera