ST. PETERSBURG, FL - The origins of carbon dioxide and water lie within the deep earth. In times long past, extensive volcanic outgassing produced our oceans and atmosphere. A new paper by the dean of the College of Marine Science sheds light on recycling of volatiles into the deep Earth by subduction and out of the deep Earth through eruption and degassing of seafloor volcanoes. Her model improves upon the standard model of subduction, known as the “subduction factory”.
Jacqueline E. Dixon, Ph.D., a geochemist by training, recently published an article in the AGU journal Geochemistry, Geophysics, Geosystems. Her research explores the origins of water and carbon dioxide on earth using measurements of water and carbon dioxide concentrations and ratios of hydrogen and other stable isotopes.
This recent paper provides a comprehensive review of and presents new data on stable isotopes in mid ocean ridge basaltic glasses. Dr. Dixon and fellow researchers show that water in enriched oceanic basalts is mostly recycled seawater that has been added to the mantle through deep melting of subducted slab igneous crust and sediments. The model proposed in the paper extends the subduction factory concept down through the transition zone of the mantle and recognizes the important role of carbon in melting of sediments and basaltic crust in the downgoing slab. These melts play a role in the complex dehydration and rehydration processes that support recycling of volatiles into the deep mantle, eventually returning to the surface in the form of lavas erupted at mid-ocean ridges and ocean islands such as Hawaii.
By: Sean Beckwith