BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:A geochemical test of the Snowball Earth hypothesis. - Francis Mac
 donald\, UC Berkeley
DTSTART:20241105T120000Z
DTEND:20241105T130000Z
UID:TALK220894@talks.cam.ac.uk
CONTACT:Dr Rachael Rhodes
DESCRIPTION:The Snowball Earth hypothesis predicts that the hydrological c
 ycle was effectively shut down for millions of years\, cutting off silicat
 e weathering of the continental crust. In this scenario\, the deep ocean s
 hould have equilibrated with the geochemistry of mantle through hydrotherm
 al exchange at mid-ocean ridges. Here we report the discovery of mantle-li
 ke Sr isotope values in marine carbonate and barite that rest directly abo
 ve ca. 717-661 Ma Sturtian glacial deposits in Oman. These new data and ge
 ochemical modeling support an extreme Snowball Earth scenario with near co
 mplete ice cover and reduced continental weathering for 56 Myr. The durati
 on and extent of the Sturtian glaciation created a major bottleneck for th
 e evolution of eukaryotes\, clearing the way for the rise of algae and ori
 gin of animals. 
LOCATION:Department of Earth Sciences\, Tilley Lecture Theatre
END:VEVENT
END:VCALENDAR