Snowball Earth climate dynamics and Cryogenian geology-geobiology

Hoffman, P.; Abbot, D.; Ashkenazy, Y.; Benn, D.; Brocks, J.; Cohen, P.; Cox, G.; Creveling, J.; Donnadieu, Y.; Erwin, D.; Fairchild, I.; Ferreira, D.; Goodman, J.; Halverson, Galen; Jansen, M.; Le Hir, G.; Love, G.; Macdonald, F.; Maloof, A.; Partin, C.; Ramstein, G.; Rose, B.; Rose, C.; Sadler, P.; Tziperman, E.; Voigt, A.; Warren, S.

doi:10.1126/sciadv.1600983

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Authors

Hoffman, P.

Abbot, D.

Ashkenazy, Y.

Benn, D.

Brocks, J.

Cohen, P.

Cox, G.

Creveling, J.

Donnadieu, Y.

Erwin, D.

Fairchild, I.

Ferreira, D.

Goodman, J.

Halverson, Galen

Jansen, M.

Le Hir, G.

Love, G.

Macdonald, F.

Maloof, A.

Partin, C.

Ramstein, G.

Rose, B.

Rose, C.

Sadler, P.

Tziperman, E.

Voigt, A.

Warren, S.

Date

2017

Type

Journal Article

Metadata

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Citation

Hoffman, P. and Abbot, D. and Ashkenazy, Y. and Benn, D. and Brocks, J. and Cohen, P. and Cox, G. et al. 2017. Snowball Earth climate dynamics and Cryogenian geology-geobiology. Science Advances. 3 (11).

Source Title

Science Advances

DOI

10.1126/sciadv.1600983

ISSN

2375-2548

School

School of Earth and Planetary Sciences (EPS)

URI

http://hdl.handle.net/20.500.11937/72300

Collection

Curtin Research Publications

Abstract

Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. Geological evidence indicates that grounded ice sheets reached sea level at all latitudes during two long-lived Cryogenian (58 and =5 My) glaciations. Combined uranium-lead and rhenium-osmium dating suggests that the older (Sturtian) glacial onset and both terminations were globally synchronous. Geochemical data imply that CO2was 102PAL (present atmospheric level) at the younger termination, consistent with a global ice cover. Sturtian glaciation followed breakup of a tropical supercontinent, and its onset coincided with the equatorial emplacement of a large igneous province. Modeling shows that the small thermal inertia of a globally frozen surface reverses the annual mean tropical atmospheric circulation, producing an equatorial desert and net snow and frost accumulation elsewhere. Oceanic ice thickens, forming a sea glacier that flows gravitationally toward the equator, sustained by the hydrologic cycle and by basal freezing and melting. Tropical ice sheets flow faster as CO2rises but lose mass and become sensitive to orbital changes. Equatorial dust accumulation engenders supraglacial oligotrophic meltwater ecosystems, favorable for cyanobacteria and certain eukaryotes. Meltwater flushing through cracks enables organic burial and submarine deposition of airborne volcanic ash. The subglacial ocean is turbulent and well mixed, in response to geothermal heating and heat loss through the ice cover, increasing with latitude. Terminal carbonate deposits, unique to Cryogenian glaciations, are products of intense weathering and ocean stratification. Whole-ocean warming and collapsing peripheral bulges allow marine coastal flooding to continue long after ice-sheet disappearance. The evolutionary legacy of Snowball Earth is perceptible in fossils and living organisms.