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Showing 1 to 13 of 13 for “"snowball Earth"”.
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Triple oxygen isotope measurements in chert: insights into the Snowball Earth glaciations
Snowball Earth events represent a critical component of the history of the planet, particularly for the trajectory of life, atmospheric oxygen, and planetary habitability. There remains a myriad of questions about the dynamics of these global glaciations, especially regarding the relationship …
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Investigating Palaeoatmospheric Composition-Climate Interactions
… of the atmosphere has changed substantially over Earth’s history, with important implications for past climate. A number of case studies will be presented which employ coupled climate model simulations to assess the strength of these chemical feedbacks on the climate. The eruption of Mount Samalas …
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Evolution of the Geohydrologic Cycle During the Past 700 Million Years
… geochemical and biological evolution of the Earth. The near-surface hydrosphere (exosphere) includes the atmosphere, cryosphere (glacial and polar ice), the biosphere, surface water, groundwater, and the oceans. The amounts of water in these various reservoirs of the hydrologic cycle have …
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Stable isotope and organic biomarker analysis of the late Proterozoic Coppercap formation in the MacKenzie Mountains
… condition proceeding the first Neoproterozoic Snowball Earth event. The Coppercap Formation directly underlies the Rapitan Group, Sturtian glacigenic deposits, and represents a depositional environment existing directly before the Cryogenian glacial episodes. Based on aryl isoprenoids, n-propyl …
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Geochronological constraints on the Trinity diamictite in Newfoundland : Implications for Ediacaran glaciation
… Formation, which has been associated with a Snowball glaciation event. The complicated regional stratigraphy and lack of precise geochronological constraints has made it difficult to determine the spatial and temporal extent of the Gaskiers glaciation. Recent recognition of a diamictite …
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Four problems in nonlinear Earth system dynamics
The Earth system — the interconnected global set of living and non-living systems comprising our planet — has undergone profound changes throughout its history. Some were slow and gradual; others dramatic and seemingly abrupt. The latter include “hyperthermal” global warming events, “Snowball …
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Geological constraints on Neoproterozoic glacial episodes
… amongst the most intense glaciations that the Earth has experienced, and are associated with major changes in the Earth System, such as the breakup of a supercontinent, the evolution of complex multicellular life and extreme geochemical perturbations. A Neoproterozoic stratigraphic scheme has …
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Climate system response to perturbations : role of ocean and sea ice
When the Earth experiences a perturbation in its radiative budget, the global ocean can buffer climate change, while sea ice may amplify its effects via a positive albedo feedback. It is therefore of interest to consider the role of the ocean in the climate's response to changes in external …
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Sedimentology of the Squantum ‘Tillite’, Boston Basin, USA: Modern Analogues and Implications for the Paleoclimate during the Gaskiers Glaciation (c. 580 Ma)
… these basins have been used as evidence for a ‘Snowball Earth-type’ glaciation at 580 Ma. However, others argue that these deposits are non-glacial debris flow deposits. To test the non-glacial interpretation of these deposits, a detailed sedimentological and basin analysis was conducted on the …
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Weathering Pathways and Limitations in Biogeochemical Models: Application to Earth System Evolution
… of climate following a Neoproterozoic snowball Earth should take more than 10(7) years, due to long-term geological limitation of global weathering rates. The timescale matches the observed gaps between extreme glaciations at this time, suggesting that the late Neoproterozoic system was …
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A low - δ 18 O intrusive breccia from the Koegel Fontein complex, South Africa
… period of crustal reworking coincides with a 'Snowball Earth' event and would have been accompanied by 18 O - depleted meteoric water. In the Cretaceous, it is assumed that a mantle plume heated the crust, causing dehydration before partial melting of the crust. The initial low - δ 18 O fluids …
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Trends in Eukaryote Body Size in an Ecological and Evolutionary Context
… disparity decreased significantly during the snowball earth events and upon the first appearance of Ediacaran organisms suggesting multiple events of selective extinction in the Proterozoic biosphere. Disparity then increased in step with the diversification of acritarch and metazoans through …
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Supercontinents and glaciation: a perspective from western Gondwana.
… the Ediacaran, which has implications for the snowball earth hypothesis and the tectonic evolution of the Paraguay Belt. These data, when combined with other evidence discussed here, are consistent with an ocean to the east of the present-day Amazonian Craton that didn’t close until the …