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Geologic evidence for an icehouse Earth before the Sturtian global glaciation.

ABSTRACT: Snowball Earth episodes, times when the planet was covered in ice, represent the most extreme climate events in Earth's history. Yet, the mechanisms that drive their initiation remain poorly constrained. Current climate models require a cool Earth to enter a Snowball state. However, existing geologic evidence suggests that Earth had a stable, warm, and ice-free climate before the Neoproterozoic Sturtian global glaciation [ca. 717 million years (Ma) ago]. Here, we present eruption ages for three felsic volcanic units interbedded with glaciolacustrine sedimentary rocks from southwest Virginia, USA, that demonstrate that glacially influenced sedimentation occurred at tropical latitudes ca. 751 Ma ago. Our findings are the first geologic evidence of a cool climate teetering on the edge of global glaciation several million years before the Sturtian Snowball Earth.

SUBMITTER: MacLennan SA

PROVIDER: S-EPMC7286673 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Geologic evidence for an icehouse Earth before the Sturtian global glaciation.

MacLennan Scott A SA Eddy Michael P MP Merschat Arthur J AJ Mehra Akshay K AK Crockford Peter W PW Maloof Adam C AC Southworth C Scott CS Schoene Blair B

Science advances 20200610 24

Snowball Earth episodes, times when the planet was covered in ice, represent the most extreme climate events in Earth's history. Yet, the mechanisms that drive their initiation remain poorly constrained. Current climate models require a cool Earth to enter a Snowball state. However, existing geologic evidence suggests that Earth had a stable, warm, and ice-free climate before the Neoproterozoic Sturtian global glaciation [ca. 717 million years (Ma) ago]. Here, we present eruption ages for three ...[more]

PMID: 32577504

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