Arthur D. Storke Memorial Professor
Earth and Environmental Sciences
61 Route 9W - PO Box 1000
Fields of interest: CO2 capture and storage via in situ mineral carbonation in peridotite and basalt; melting and reactive melt transport in the Earth's mantle and lower crust; igneous processes in forming the Earth's crust; density instabilities, ductile deformation and evolution of the lower crust; subduction zone geotherms; and the mechanisms for intermediate depth earthquakes.
Recently, I have added mineral carbonation and hydration in peridotite and mafic rocks to my research program. This is a reactive transport problem, very similar to the work I've done on reactive transport of melt in the upper mantle and lower crust, there are fantastic field areas where active, ongoing mineral carbonation and hydration can be observed, and the physical mechanisms that control key processes are not well understood. We are focusing on understanding processes in natural systems, particularly “reaction driven cracking”, with relevance to engineered geological capture and storage of CO2, stimulation of geothermal reservoirs, in situ mining, and extraction of hydrocarbon resources from tight formations.
For decades, my primary research interest has been in the genesis and evolution of the Earth's crust in the ocean basins, in arcs, and in continents. I approach this topic from the perspective that reactions between melt and rock during transport through the upper mantle are as important as melting, mixing, and crystal fractionation processes in producing different crustal bulk compositions in different tectonic settings. I’ve been fascinated by the stark compositional difference between oceanic and continental crust, and in my research I have gravitated toward end-member examples of magmatic processes: oceanic spreading ridges, and subduction-related volcanic arcs such as the Aleutians where the composition of average lavas and exposed plutonic rocks closely resembles continental crust. In an ongoing effort, I've tried to develop a general theory that explains how reactive melt transport varies along different geothermal gradients, with, 1. mineral dissolution and focusing of flow into high permeability channels in hot, upwelling mantle, 2. diffuse flow where there is a low melt flux into conductively cooled, shallow mantle, and, 3. hydrofracture where high melt flux and crystallization due to cooling clog porosity, leading to ponding of magma and increasing melt pressure. I’ve also become very interested in gravitational instabilities that can remove dense lithologies from the base of the crust, and transport buoyant subducted sediments and felsic igneous rocks from subduction zones back into the crust, and I hope to pursue investigations of metasediments in lower crustal granulite terrains: how do they get down there?
In studying layered intrusions and lower oceanic crust, I’ve tried to understand a few of the many possible mechanisms for forming both compositional and modal layering in gabbros, via injection of layer parallel sills, and via sudden changes in pressure that can modify the assemblage of minerals precipitating from a cooling magma. This research led to general ideas about formation of oceanic crust, via a “sheeted sills” mechanism in which the lower crust crystallizes from many small sills, injected at depths throughout the crust. This end-member process stands in contrast to the “gabbro glacier” hypothesis, in which all oceanic plutonic rocks crystallize in a single, shallow melt lens and undergo ductile flow downward and outward to “fill” the lower crust. A related issue is the mode of cooling of the oceanic lower crust; via conduction with limited, diffuse fluid flow, or via rapid, focused hydrothermal convection. Trying to quantify and constrain these hypotheses, and to determine which processes predominate in different tectonic settings, has motivated a lot of research over the past 15 years.
I've been very fortunate to work with a large number of tolerant geophysicists (Jack Whitehead, Einat Aharonov, Steve Holbrook, Marc Spiegelman, Greg Hirth, Jun Korenaga, Matthew Jull, and others) who have led me into the world of geodynamics. I am grateful to them all, particularly Greg Hirth, with whom I have been able to pursue interdisciplinary studies.
Finally, not that long ago, I was a founding partner of Dihedral Exploration, mineral exploration consultants specializing in field work requiring technical climbing skills. Searching for ore deposits took me to British Columbia, Alaska and Greenland. I've recently started teaching a new course, Earth Resources for Sustainable Development, which covers some of that field, as well as energy resources, water, soil and fertilizer. I’ve been writing general articles and giving public presentations on this topic
Referenced in the Following News Items:
Featured in the Following Videos:
The seismic mid-lithosphere discontinuity Earth and Planetary Science Letters Volume: 414 p.: 45-57 (2015)
Distinctly different parental magmas for calc-alkaline plutons and tholeiitic lavas in the central and eastern Aleutian arc Earth and Planetary Science Letters Volume: 431 (2015) 10.1016/j.epsl.2015.07.058
Constraints on the composition of the Aleutian arc lower crust from VP/VS Geophysical Research Letters Volume: 40 p.: 2579–2584 (2013) 10.1002/grl.50375
Reaction-driven cracking during retrograde metamorphism: Olivine hydration and carbonation Earth and Planetary Science Letters Volume: 345–348 p.: p. 81 (2012)
Coexisting serpentine and quartz from carbonate-bearing serpentinized peridotite in the Samail Ophiolite, Oman Mineralogy and Petrology Volume: 164 (2012)
Differentiation of the continental crust by relamination Earth and Planetary Science Letters 06/02/2011 Volume: 307 p.: 15 (2011)
Rates and Mechanisms of Mineral Carbonation in Peridotite: Natural Processes and Recipes for Enhanced, in situ CO2 Capture and Storage Annual Review of Earth and Planetary Sciences Volume: 39 p.: 93 (2011)
Diapirs as the source of the sediment signature in arc lavas Nature Geoscience Volume: 4 (2011)
The case for reactive crystallization at mid-ocean ridges Journal of Petrology (2010)
Rates and mechanisms of peridotite carbonation: preliminary data from Oman, recipes for enhanced, in situ CO2 capture & storage, and avenues for continued research Annual Reviews of Earth & Planetary Science (2010)
Composition and genesis of depleted mantle peridotites from the Wadi Tayin massif, Oman ophiolite. Major and trace element geochemistry, and Os isotope and PGE systematics Journal of Petrology Volume: 51 (2010)
Investigation of the strength contrast at the Moho: A case study from the Oman Ophiolite Geology Volume: 38 (2010)
Microstructural and rheological evolution of a mantle shear zone Journal of Petrology Volume: 51 (2010)
Trapped melt in the Josephine peridotite: Implications for permeability and melt extraction in the upper mantle Journal of Petrology Volume: 51 (2010)
A felsic end to Bushveld differentiation Journal of Petrology Volume: 51 (2010)
Enhanced in situ carbonation of peridotite for permanent CO2 storage Geochimica Et Cosmochimica Acta Jun Volume: 73 Issue: 13 p.: A848-A848 (2009)
Permanent storage of carbon dioxide in geological reservoirs by mineral carbonation Nature Geoscience Volume: 2 p.: 837-841 (2009)
Cooling rates in the lower crust of the Oman ophiolite: Ca in olivine, revisited Earth and Planetary Science Letters Mar 1 Volume: 267 Issue: 1-2 p.: 69-82 (2008) DOI 10.1016/j.epsi.2007.11.034
Microstructures in Hole 1274A peridotites, ODP Leg 209, Mid-Atlantic Ridge: Tracking the fate of melts percolating in peridotite as the lithosphere is intercepted Geochemistry Geophysics Geosystems Mar 18 Volume: 9 p.: - (2008) Doi 10.1029/2007gc001726
Reconstruction of the Talkeetna intraoceanic arc of Alaska through thermobarometry Journal of Geophysical Research-Solid Earth Mar 7 Volume: 113 Issue: B3 p.: - (2008) Doi 10.1029/2007jb005208
Recycled crust controls contrasting source compositions of Mesozoic and Cenozoic basalts in the North China Craton Geochimica Et Cosmochimica Acta May 1 Volume: 72 Issue: 9 p.: 2349-2376 (2008) DOI 10.1016/j.gca.2008.02.018
Geochemistry and magmatic history of eclogues and ultramafic rocks from the Chinese continental scientific drill hole: Subduction and ultrahigh-pressure metamorphism of lower crustal cumulates Chemical Geology Jan 15 Volume: 247 Issue: 1-2 p.: 133-153 (2008) DOI 10.1016/j.chemgeo.2007.10.016
In situ carbonation of peridotite for CO2 storage Proc. Nat. Acad. Sci. 11/2008 Volume: 105 Issue: 45 p.: 17295-17300 (2008)
In situ carbonation of peridotite for CO2 storage Proceedings of the National Academy of Sciences of the United States of America Nov 11 Volume: 105 Issue: 45 p.: 17295-17300 (2008) DOI 10.1073/pnas.0805794105
Melt-peridotite reaction in the mantle: Grain-scale processes and geological applications Journal of China University of Geosciences Jun Volume: 18 p.: 194-197 (2007)
Nonvolcanic seafloor spreading and corner-flow rotation accommodated by extensional faulting at 15 degrees N on the Mid-Atlantic Ridge: A structural synthesis of ODP Leg 209 Geochemistry Geophysics Geosystems Jun 28 Volume: 8 p.: - (2007) Doi 10.1029/2006gc001567
A periodic shear-heating mechanism for intermediate-depth earthquakes in the mantle Nature Apr 12 Volume: 446 Issue: 7137 p.: 787-790 (2007) Doi 10.1038/Nature05717
Trace elements in clinopyroxenes from Aleutian xenoliths: Implications for primitive subduction magmatism in an island arc Earth and Planetary Science Letters Apr 30 Volume: 256 Issue: 3-4 p.: 617-632 (2007) DOI 10.1016/j.epsl.2007.02.015
Trench-parallel anisotropy produced by foundering of arc lower crust Science Jul 6 Volume: 317 Issue: 5834 p.: 108-111 (2007) DOI 10.1126/science.1141269
Ultra-depleted, shallow cratonic mantle beneath West Greenland: dunitic xenoliths from Ubekendt Ejland Contributions to Mineralogy and Petrology Sep Volume: 152 Issue: 3 p.: 335-347 (2006) DOI 10.1007/s00410-006-0109-0