The Earth Science Colloquium Series presents:
Subducting Carbon
with Dr. Terry Plank, Arthur D. Storke Memorial Professor at the Department of Earth and Environmental Science, Columbia University.
Abstract: In addition to its familiar cycling between the terrestrial biosphere and atmosphere, carbon moves from microfossils on the seafloor to erupting volcanoes and deep diamonds, in a cycle driven by plate tectonics. Subduction links surface biological processes with the deep Earth, creating a planet suffused with the signature of life. The largest fIux of surficial carbon that subducts at trenches globally is sedimentary. This is paradoxical, as most carbonate dissolves and organic carbon oxidizes in the ocean before reaching the deep seafIoor. Nonetheless, different events conspire to deliver variable fIuxes of carbon, some of them large, to different trench sectors. Thus, sedimentary carbon subduction is not a global phenomenon – it is a
regional one where heterogeneity rules.
Alberto Malinverno and I have spent almost a decade working on a project to calculate the fIux and isotopic composition of sedimentary organic and inorganic carbon at the world’s trenches. Our calculations are at the scale of kms along the trench, and so make predictions relevant to individual volcanoes as well as entire segments of the Ring of Fire. In this talk, we’ll use these data to start to answer some questions. How often is the equivalent of the entire biosphere of carbon subducted? Do some volcanoes emit CO2 derived from subducted carbonate vs. organic carbon? How important is terrestrial organic carbon, delivered in rivers, vs. marine organic carbon in supplying deep sea trenches? Are your diamonds recycled? This talk has something for everyone, and will highlight several Lamont scientists and students.
The Earth Science Colloquium Series, sponsored by Lamont-Doherty Earth Observatory and Columbia University Department of Earth and Environmental Sciences (DEES), provides a lively forum for discussing a wide variety of topics within the Earth sciences and related fields. Colloquia are attended by the full range of scientific and technical staff at LDEO. Colloquium attendance is required of all pre-orals DEES graduate students. The Colloquium Series supports the Lamont Seminar Diversity Initiative.
