A neoproterozoic snowball earth

  title={A neoproterozoic snowball earth},
  author={Hoffman and Kaufman and Halverson and Schrag},
  volume={281 5381},
Negative carbon isotope anomalies in carbonate rocks bracketing Neoproterozoic glacial deposits in Namibia, combined with estimates of thermal subsidence history, suggest that biological productivity in the surface ocean collapsed for millions of years. This collapse can be explained by a global glaciation (that is, a snowball Earth), which ended abruptly when subaerial volcanic outgassing raised atmospheric carbon dioxide to about 350 times the modern level. The rapid termination would have… 

Neoproterozoic syn‐glacial carbonate precipitation and implications for a snowball Earth

Modelling results suggest that a small degree of chemical weathering during glaciation would have been capable of maintaining high seawater Mg/Ca ratios and carbonate precipitation throughout the Sturtian glaciation, consistent with a severe ice age but challenges predictions of biogeochemical cycling during the endmember 'hard snowball' models.

Climatic cycles during a Neoproterozoic “snowball” glacial epoch

The profound glaciations of the Neoproterozoic Cryogenian period (ca. 850–544 Ma) represent an extreme climatic mode when, it is claimed, Earth was fully or almost completely covered with ice for

Carbonate Deposition, Climate Stability, and Neoproterozoic Ice Ages

Neoproterozoic ice ages of near-global extent and multimillion-year duration and the formation of distinctive sedimentary (cap) carbonates can be understood in terms of the greater sensitivity of the Precambrian carbon cycle to the loss of shallow-water environments and CO2-climate feedback on ice-sheet growth.

Carbon isotopic composition of Neoproterozoic glacial carbonates as a test of paleoceanographic models for snowball Earth phenomena

Consistently positive carbon isotopic values were obtained from in situ peloids, ooids, and stromatolitic carbonate within Neoproterozoic glacial successions in northern Namibia, central Australia,

Estimating Duration and Intensity of Neoproterozoic Snowball Glaciations from Ir Anomalies

The authors' data confirm the presence of extended global Neoproterozoic glaciations and indicate that the duration of the Marinoan glacial episode was at least 3 million, and most likely 12 million, years.

Sedimentary and geochemical characteristics of Sinian cap carbonates in the Upper Yangtze region

A global-scale glaciation occurred at about 600 Ma ago. As a result, the Earth became the “Snowball Earth”. The glaciation came to the end abruptly when atmospheric carbon dioxide increased to such

Neoproterozoic “snowball Earth”: Dynamic sea ice over a quiescent ocean

[1] Low-latitude sea level glacial deposits suggest the existence of “snowball Earth” conditions in the Neoproterozoic. Previous modeling studies have offered conflicting support for the snowball

Sedimentary challenge to Snowball Earth

Evidence from the magnetic field fossilized in sedimentary rocks suggests that, more than 600 million years ago, ice occupied tropical latitudes. A popular explanation for these findings, the

Snowball Earth termination by destabilization of equatorial permafrost methane clathrate

The findings suggest that methane released from low-latitude permafrost clathrates therefore acted as a trigger and/or strong positive feedback for deglaciation and warming and may represent one particularly important mechanism active during conditions of strong climate forcing.

Biomarker Evidence for Photosynthesis During Neoproterozoic Glaciation

Laterally extensive black shales deposited on the São Francisco craton in southeastern Brazil during low-latitude Neoproterozoic glaciation are interpreted as representing the preserved record of abundant marine primary productivity from glacial times, providing important constraints for parts of the “Snowball Earth” hypothesis.



Comparative Earth History and Late Permian Mass Extinction

The repeated association during the late Neoproterozoic Era of large carbon-isotopic excursions, continental glaciation, and stratigraphically anomalous carbonate precipitation provides a framework

Isotopes, ice ages, and terminal Proterozoic earth history.

Detailed correlations of ancient glacial deposits, based on temporal records of carbon and strontium isotopes in seawater, indicate four (and perhaps five) discrete ice ages in the terminal

Susceptibility of the early Earth to irreversible glaciation caused by carbon dioxide clouds

The authors' simulations of the early Earth, incorporating the possible formation of highly reflective CO2 clouds, suggest that the Earth might not be habitable today had it not been warm during the first part of its history.

Warming early Mars with carbon dioxide clouds that scatter infrared radiation.

Model calculations show that the surface of early Mars could have been warmed through a scattering variant of the greenhouse effect, resulting from the ability of the carbon dioxide ice clouds to reflect the outgoing thermal radiation back to the surface.

Are Neoproterozoic glacial deposits preserved on the margins of Laurentia related to the fragmentation of two supercontinents

Remarkably similar deposits representing two Neoproterozoic glaciations are present on the west and east sides of Laurentia. Although now located near the margins of Laurentia, these glaciogenic

Late Proterozoic rise in atmospheric oxygen concentration inferred from phylogenetic and sulphur-isotope studies

The evolution of non-photosynthetic sulphide-oxidizing bacteria was contemporaneous with a large shift in the isotopic composition of biogenic sedimentary sulphides between 0.64 and 1.05 billion

Cool-water Carbonates

This book is a collected series of papers on the sedimentary geology of carbonate sediments deposited on shelves and offshore banks in cool to cold oceans. Contributions come mainly from a workshop

Anomalous carbonate precipitates: is the Precambrian the key to the Permian?

Late Permian reefs of the Capitan complex, west Texas; the Magnesian Limestone, England; Chuenmuping reef, south China; and elsewhere contain anomalously large volumes of aragonite and calcite marine cements and sea-floor crusts, as well as abundant microbial precipitates, interpreted to have formed in a stratified ocean with anoxic deep waters enriched in carbonate alkalinity.

Secular variation in carbon isotope ratios from Upper Proterozoic successions of Svalbard and East Greenland

Isotopic compositions of isolated samples from other localities are consistent with a worldwide extended interval of enhanced organic burial and consequent net survival of oxidized material, probably O2, just before the initial radiation of metazoans.

Continental-pelagic carbonate partitioning and the global carbonate-silicate cycle.

Model results suggest that carbonate deposition patterns established during the Cenozoic may be pushing the Earth system from the continental to the pelagic mode on a time scale of 10(8) yr, with a possible consequent order-of-magnitude increase in the metamorphic CO2 flux to the atmosphere.