Steven B Shirey

Senior Staff Scientist

Department of Terrestrial Magnetism

Carnegie Institution for Science

✦ The human occupied submersible DSRV Alvin a mile and a half deep on a seamount on the Pacific Ocean floor, OASIS Cruise, Nov 2016. Funded by the National Science Foundation. (photo: courtesy Dan Fornari ††)

✦ Acadia National Park, ME (2009)

✦ Fall AGU Meeting, San Francisco (2010)

✦ 4th Int'l Diamond School, Italy (2018)

New results

✦ A blue, boron-bearing diamond, with dark inclusions of a mineral called ferropericlase that was one of 26 inclusion-containing blue diamoinds examined as part of the study. This gem weighs 0.03 carats. Photo by Evan M. Smith/© 2018 GIA

A new study published in the August 2 issue of the journal Nature (Smith, E. M., Shirey, S. B., Richardson S. H., Nestola, F., Bullock, E. S., Wang, J., & Wang, W. (2018). Blue boron-bearing diamonds from Earth’s lower mantle. Nature, 560, 84–87. http://doi.org/10.1038/s41586-018-0334-5 ) demonstrates that the world's most valuable diamonds, those that are blue and thus boron-containing, are also perhaps the world's most deeply-derived diamonds. When these diamonds do contain mineral inclusions, the inclusions are low-pressure reaction products of high pressure minerals including bridgmanite, ferropericlase, Ca-pervoskite, and stishovite among others. These minerals allow an estimate of depths of origin around or below 660 km in Earth's mantle. See the Carnegie Institution for Science press release here. See the Deep Carbon Observatory (DCO) press release here.

Where

✦ The Broad Branch Road Campus of Department of Terrestrial Magnetism and the Geophysical Laboratory has been located in residential northwest Washington, DC for more that 100 years.

Steven Shirey is a senior staff member of the five-person Geochemistry and Cosmochemistry Group of the Department of Terrestrial Magnetism of the Carnegie Institution for Science. The Carnegie Institution for Science is the nation's oldest privately-endowed research organization dedicated to fundamental scientific research. In addition to the Department of Terrestrial Magnetism, it has 5 other research departments spread across the United States and in Chile.

What

✦ This roadcut outcrop from the Grenville Province of Ontario epitomizes the processes occurring during the evolution of continental crust. Plagioclase and potassium feldspar are crystallizing in a band parallel to the evident local fold axis.

Independently and with his mentoring of student-interns, PhD students, and postdoctoral fellows, Steve researches major geological questions about the igneous evolution of the solid Earth. Trace element and isotopic compositions of ancient minerals and rocks are employed to understand some of the deepest and oldest magmatic and geodynamic processes that have shaped Earth since its formation.

Why

The ages of the rocks on Earth's surface are displayed in this map from the USGS. The age of continental rocks is as follows: older than 2.5 billion years old in orange; 2.5 to 1.6 billion years old in pink, 1.6 to 1.0 billion years old in green, 1.0 to 0.54 billion years old in purple and younger than 0.54 billion years old in blue and yellow. The ocean floor is in shades of blue and is less than 0.2 billion years old.

Steve's main research emphasis has been on the formation of the continents from Earth's mantle, the only geologic process that spans most of Earth history and records the conditions on the ancient Earth that led to life. A recurring research theme has been to show how ancient episodes of mantle-derived magmatism and crust formation differ from those today. Field work on modern rocks (like seen above with this ALVIN dive to collect ocean floor pillow basalt) is as important as that on ancient rocks to understand how the Earth's geologic processes have changed. Steve's most recent notable work has been on superdeep diamonds to understand the hidden deep subsurface mantle convection portion of plate tectonics (see above).

Academic Training

BA, Geology (1972), Dartmouth College

MS, Geology (1975), University of Massachusetts Amherst

PhD, Geochemistry (1984), State University of New York at Stony Brook

Carnegie Fellowship, Isotope Geochemistry (1984-1985), Carnegie Institution for Science

Address & Contact Information

Department of Terrestrial Magnetism

Carnegie Institution for Science

5241 Broad Branch Road, NW

Washington, DC 20015 USA

Cell: +1 (301) 792-9083

Office: +1 (301) 478-8473

Email: sshirey-at-carnegiescience-dot-edu

Skype: stevenshirey

ORCID ID# 0000-0002-8544-4596

†† Photo: © Woods Hole Oceanographic Institution, National Deep Submergence Facility, courtesy of Dan Fornari - MISO Facility (http://www.whoi.edu/miso/)