THE NEOPROTEROZOIC (1000-540 MA) GLACIAL INTERVALS - NO MORE SNOWBALLEARTH

The Neoproterozoic interval (1000-540 Ma) contains ample evidence for a series of glacial intervals. These include the 750-700 Ma Sturtian g laciation, the 625-580 Ma Marinoan-Vendian glaciation and the 600-550 Ma Sinian glaciation. Paleomagnetic evidence has suggested that many o f these glaciations occurred at tropical latitudes (less-than-or-equal -to 25-degrees) and this led to a number of theories that attempt to e xplain the occurrence of these anomalously low latitude glaciations (e .g., an increase in the, axial tilt of the earth, an equatorial low-or bit ice-ring, rapid equator to pole continental drift, incorrect ident ification of impact deposits as glacial deposits or secondary magnetiz ations misidentified as primary). New paleomagnetic data for Laurentia , China, Baltica and parts of Gondwana are combined with a reanalysis of previously published data to demonstrate that the Neoproterozoic gl aciations may well all have occurred above 25-degrees latitude. Climat e models using a juvenile Sun of slightly lower luminosity, lower CO2 levels and coupling to Milankovitch cycles suggest, that ice sheets co uld extend to within +/- 25-degrees of the Neoproterozoic equator. Thu s, the new paleomagnetic data and climate models offer an alternative explanation for the Neoproterozoic glaciations that is consistent with the waxing and waning of intermediate latitude ice sheets to form the conformable sequences of warm climate-cold climate strata.