“Snowball Earth” Hypothesis and the Palaeoenvironment for Life Evolution during the Late Neoproterozoic

Key words: 
• Neoproterozoic

Abstract: During the Neoproterozoic, earth suffered through at least two globeengulfing ice age. Researchers proposed “Snowball earth”　hypothesis to explain a series of puzzling Neoproterozoic sedimentary recordings. This hypothesis has become an ancient widow for the study of global glaciation and bioradiation aftermath. Other researchers, however, do not agree that　the earth has been completely icecovered. They proposed alternative hypotheses, such as “Slushball/ Semifrozen Earth”, and “Thinice”models. Although, each hypothesis cannot　explain all the geological and geochemical recordings, more and more evidence, especially, molecular　organic geochemical and biological evidences show that the ocean was not entirely icecovered during “Snowball Earth”age. Thin ice sheets or open water zones remained in tropical areas. The open water zone is essential for the survival and evolution of photosynthetic organisms, which would make a significant impact on the “Cambrian Bioradiation” and the evolution of life on the earth. 