COG3 Seminar – Doug Reusch (UMaine Farmington)

A serendipitous link between Appalachian ophiolites and Earth’s climate.

The title, a take-off on Bill Church’s “The serendipitous link between Caledonide-Appalachian eclogites and ophiolites,” is rooted in the insightful observation by his student Bob Stevens—detrital chromite occurs in the foreland basin sand beneath the west Newfoundland ophiolites. The chromite content is similar to that of the parental peridotite. But where is the olivine, a relatively soluble mineral capable of removing two molecules of carbon dioxide per molecule dissolved? This question bears both on paleoclimate and the current climate emergency. In the geologic record, certain collisions that quickly raise the “right rocks” into the “right climate” seem to correspond with the onset of global cooling. Looking forward, is there a way to exploit mantle peridotite, an effectively infinite source of antacid, to neutralize the Industrial Age carbon that, even in a net-zero-emissions world, will still be in excess? Assuming long-term storage of organic carbon is precarious, storage of carbonate requires a source of alkalinity on the scale of the cumulative fossil fuel extraction. Prospective on-land sites are few and subject to the NIMBY response. In the oceans, Grand Canyon-scale transform fault scarps constitute untapped sources of both chemical and gravitational disequilibrium. The Lost City hydrothermal field emits high pH fluids—through careful mapping and strategic fracturing, could this process be scaled up sufficiently, affordably, and quickly enough to undo the damage of fossil fuel carbon?

About this series:
The Chemical Oceanography, Geology, Geochemistry, and Geobiology Seminar [COG3] is a student-run seminar series. Topics include chemical oceanography, geology, geochemistry, and geobiology. Contact cog3_seminar_organizers@mit.edu for more information and Zoom password.