The ∼450 million years of Neoproterozoic time (1000-542Ma) was a remarkable episode of change in the Earth system and the biosphere. Here we develop and explore the hypothesis that explosive volcanism was at least partly responsible for Neoproterozoic climate change, synopsized as the “Volcanic winter to snowball Earth” (VW2SE) hypothesis. We review how climate cools as a result of sulfuric acid aerosols injected into the stratosphere by violent volcanic eruptions. A protracted increase in explosive volcanism could disrupt Earth’s radiative balance by continuously injecting sulfur aerosols into the stratosphere, causing cooling that could lead to glaciation. This mechanism would be especially effective when acting in concert with other agents for cooling. We show that the global Neoproterozoic magmatic flux was intense, so that explosive volcanism episodicly had a major effect on climate. Neoproterozoic volcanism and glacial activity happened about the same times in the Cryogenian and Ediacaran periods with no glaciation and reduced igneous activity in the Tonian Period. Glaciation followed soon after igneous activity increased as the supercontinent Rodinia broke apart, suggesting a causal relationship. The tectonic setting of climate-controlling explosive volcanism changed systematically over the Neoproterozoic supercontinent cycle, from extension-related early to arc-related late. Marinoan (∼635 Ma) glaciation in particular corresponds to a peak time of subduction-related igneous activity in the Arabian-Nubian Shield and the East African Orogen. Isotopic chemostratigraphies are generally consistent with VW2SE hypothesis. These observations cumulatively support the VW2SE hypothesis as a viable explanation for what solid Earth processes caused Neoproterozoic climate oscillations.
|Original language||American English|
|Title of host publication||Modern Approaches in Solid Earth Sciences|
|Publisher||Springer International Publishing|
|Number of pages||25|
|State||Published - 2008|
|Name||Modern Approaches in Solid Earth Sciences|
Bibliographical noteFunding Information:
This research was supported by USA-Israel Binational Science Foundation grant 2002337 and NSF grant EAR-0509486. We especially thank S. Self for helping us understand the climate effects of explosive volcanism and J. Alt for comments about S isotopes. the GSA Pardee Symposium convenors for the invitation to participate in the session, which greatly stimulated our thinking about this problem.We appreciate the critical comments of R. M. Mitterer, K. Muehlenbachs, and M. De Wit. This is UTD Geosciences contribution # 1121.
© Springer Science+Business Media B.V. 2008.