Snowball Earth ocean chemistry driven by extensive ridge volcanism during Rodinia breakup
| Autor: | Toby Tyrrell, Eelco J. Rohling, Thomas M. Gernon, Martin R. Palmer, Thea K Hincks |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
010504 meteorology & atmospheric sciences
Earth science 010502 geochemistry & geophysics Breakup Palagonite 01 natural sciences Supercontinent Rodinia Deglaciation General Earth and Planetary Sciences Snowball Earth Sedimentary rock Deposition (chemistry) Geology 0105 earth and related environmental sciences |
| Zdroj: | Gernon, T, Hincks, T K, Tyrrell, T, Rholing, E & Palmer, M 2016, ' Snowball Earth ocean chemistry driven by extensive ridge volcanism during Rodinia breakup ', Nature Geoscience, vol. 9, no. 3, pp. 242-248 . https://doi.org/10.1038/ngeo2632 |
| Popis: | During Neoproterozoic Snowball Earth glaciations, the oceans gained massive amounts of alkalinity, culminating in the deposition of massive cap carbonates on deglaciation. Changes in terrestrial runoff associated with both breakup of the Rodinia supercontinent and deglaciation can explain some, but not all of the requisite changes in ocean chemistry. Submarine volcanism along shallow ridges formed during supercontinent breakup results in the formation of large volumes of glassy hyaloclastite, which readily alters to palagonite. Here we estimate fluxes of calcium, magnesium, phosphorus, silica and bicarbonate associated with these shallow-ridge processes, and argue that extensive submarine volcanism during the breakup of Rodinia made an important contribution to changes in ocean chemistry during Snowball Earth glaciations. We use Monte Carlo simulations to show that widespread hyaloclastite alteration under near-global sea-ice cover could lead to Ca2+ and Mg2+ supersaturation over the course of the glaciation that is sufficient to explain the volume of cap carbonates deposited. Furthermore, our conservative estimates of phosphorus release are sufficient to explain the observed P:Fe ratios in sedimentary iron formations from this time. This large phosphorus release may have fuelled primary productivity, which in turn would have contributed to atmospheric O2 rises that followed Snowball Earth episodes. The Cryogenian Snowball Earth glaciations were followed by the deposition of massive cap carbonates. Geochemical modelling suggests that shallow-ridge volcanism supplied much of the alkalinity and cations that fuelled this deposition. |
| Databáze: | OpenAIRE |
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