Big Ideas in Volcanology #08:


Rock weathering alone can’t explain the abundance of the more volatile materials (e.g. H2O, CO2) in the current hydrosphere and ancient sediments. If these species all comes with an early ocean, this would be very acid. Instead if gas seeps gradually, acid rain falls on the Earth and is neutralized during weathering making changes in the composition of the oceans more gradual and moderate.

This was the first theory on Earth’s hydrosphere formation and still the predominant in the last decades. But this Big Idea remarkably evolved in the last decades and is unlikely to change back. Nowadays volcanic degassing is no longer considered to be the unique and dominant source of volatile elements for the current hydrosphere, and volatile materials have been demonstrated to be related to various sources such as the incomplete accretion of nebular material, late veneer events and recycling via deep slab.

More Big Ideas in Volcanology can be found here, and some of the potential sub-ideas related to this topic follow.

#08.1 _ Earth’s primordial atmosphere has different origin than volcanic degassing

#08.2 _ Volcanism contributed to the formation of a secondary atmosphere and oceans

#08.3 _ No free oxygen was part of the Earth’s primordial atmosphere

#08.4 _ Other external sources had a significant role in the formation of the current hydrosphere

#08.5 _ Some of Earth’s circumstances have been observed also on other planets of the Solar System

#08.6 _ Other science fields and new techniques can help develop the current theories


Earth’s hydrosphere comes from Volcanic Degassing

#08.1                    #08.2                    #08.3                    #08.4                    #08.5                    #08.6