Stratigraphic, geochronological, and paleomagnetic constraints upon the Neoproterozoic climatic paradox

Teria estado o planeta Terra totalmente coberto por gelo centenas de milhões de anos atrás?

“…Em revisão sobre os depósitos glaciais pré-cambrianos, apresentada em Evans (2000), foi demonstrado que grande parte desses depósitos glaciais teria se formado em regiões litorâneas e, em sua maioria, entre o Equador e o paralelo de 10º. Nenhum dos depósitos glaciais apresentou-se em paralelos maiores do que 60º.…”

Integrated Ediacaran chronostratigraphy, Wernecke Mountains, northwestern Canada

“…543 Ma) is based on U-Pb zircon dates from Namibia , Siberia (Bowring et al, 1993) and Oman (Amthor et al, 2003). Testing the timing of multiple, globally synchronous glacial events by radiometric dating has not been possible (Evans, 2000). Thus, the best possible chronostratigraphic resolution comes from integrated stratigraphic approaches.…”

Geochemical constraints on the origin of Doushantuo cap carbonates in the Yangtze Gorges area, South China

“…One of the most intriguing is the Marinoan glaciation that extended into equatorial latitudes (Evans, 2000;Hoffman and Schrag, 2002;Hoffman and Li, 2009). Most Marinoan glacial deposits are directly overlain by "cap carbonates" with peculiar sedimentary features and negative carbon isotope signatures (Kennedy, 1996;Hoffman et al, 1998;James et al, 2001;Hoffman and Schrag, 2002;Jiang et al, 2003a;Frimmel and Folling, 2004;Shields et al, 2007a, b;Zhou and Xiao, 2007;Shen et al, 2008), implying severe and rapid climatic changes which are thought to serve as an 'environmental filter' for biological evolution (Hoffman et al, 1998;Runnegar, 2000;Hoffman and Schrag, 2002).…”