Abstract
Natur al Sciences
Volcano Location Could Be GreenhouseIcehouse Key A new Rice University-led study examines whether continental-arc volcanoes like Mount Etna in Sicily may have produced high levels of carbon dioxide during long greenhouse periods in Earth’s ancient past.
Photo: NASA
The journal Geosphere published a study by Rice earth science faculty that links the Earth’s repeated long-term flip-flopping between greenhouse and icehouse states over the past 500 million years to the episodic flare-up of volcanoes at key locations along continental arcs. Such eruptions could release enormous amounts of carbon dioxide into the atmosphere. “Continents store massive amounts of carbon dioxide in sedimentary carbonates like limestone and marble, and it appears that these reservoirs are tapped from time to time by volcanoes, which release large amounts of carbon dioxide into the atmosphere,” said Professor Cin-Ty Lee, who along with graduate student Benjamin Slotnick, Professor Adrian Lenardic, Professor Gerald Dickens and Associate Professor Rajdeep Dasgupta, all in the Department of Earth Science, led the study. Lee is a petrologist and geochemist whose research interests include the formation and evolution of continents as well as the connec-
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tions between deep Earth and its oceans and atmosphere. “One process that can release carbon dioxide from these carbonates is interaction with magma,” Lee said. “But that rarely happens on Earth today because most volcanoes are located on island arcs, tectonic plate boundaries that don’t contain continental crust.” Lee and his colleagues showed that tectonic activity drives an episodic flare-up of volcanoes along continental arcs, particularly during periods when oceans are forming and continents are breaking apart. Earth’s climate continually cycles between greenhouse and icehouse states, which each last on timescales of 10 million to 100 million years. Icehouse states — like the one Earth has been in for the past 50 million years — are marked by ice at the poles and periods of glacial activity. By contrast, the warmer greenhouse states are marked by increased carbon dioxide in the atmosphere and by an ice-free surface, even at the poles. The last greenhouse S u m m e r 2 0 1 3 · R i ce M a g a z i n e
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