David James is a member of the American Geophysical Union (AGU), the Seismological Society of America (SSA), and the Society of Exploration Geophysicists and a fellow of the Royal Astronomical Society. He is also chairman of the PASSCAL Standing Committee and a distinguished IRIS/SSA Lecturer. He was also an editor for the AGU, and a member of the Advisory Committee for Earth Sciences to the National Science Foundation.

Multidisciplinary research has been a mainstay at the Department of Terrestrial Magnetism (DTM) for decades. In this tradition, geophysicist David James uses both geophysics and geochemistry to study the structure, formation, and evolution of the continents. Much of his early work was dedicated to the study of subduction zones, where the tectonic plates collide to form mountain ranges, earthquakes, and volcanoes. In this work James used both geophysics and geochemistry to investigate how subduction processes created new crust and modified existing crust along the active Andean margin of South America — the modern analogue to the formation of old mountain belts such as the Appalachians. He produced the first three-dimensional seismic image of crustal structure beneath the central Andes and, in the early 1970s, published the first comprehensive plate tectonic model for the evolution of the area that synthesized seismic, gravitational, geochemical, and geological data. As part of his Andean research, James also devoted more than a decade to isotopic and trace element studies, where he helped pioneer the use of stable oxygen isotopes combined with radiogenic isotopes to understand the origin of subduction zone magmas.

Measurements from the Kaapvaal Craton area help determine the evolution of the region. On top, black circles show broadband seismic stations. White circles with white bars show the direction of fast mantle shear-wave propagation. Black lines are geological province boundaries; and the filled diamonds denote major kimberlite localities keyed by Re/Os model ages of mantle xenoliths (blue, > 2.5 Byr; green, 2-2.5 Byr; red, < 2 Byr). The middle panel is the base of the continental crust; blue denotes thin crust, red thick crust. At bottom are P-wave anomalies in the upper mantle. Anomalies in blue outline the deep mantle root of the craton.

James was foremost among those who advocated harnessing revolutionary digital and microelectronics technology to design and build a powerful new class of portable broadband seismometer systems. He was a leader in promoting the development of portable broadband array instrumentation and methodology that DTM and others now use worldwide to make 3-D images of the Earth’s crust and deep interior. As part of his portable broadband seismic studies, James was a principal organizer of the Southern Africa Seismic Experiment, the argest of its kind ever undertaken and a centerpiece of the multidisciplinary Kaapvaal Craton Project, which addresses how cratons—the earliest continental masses on Earth — formed and evolved. James published 3-D images of the crust-mantle boundary beneath the cratonszand their deep mantle “roots,” showing that the Archean cratons have a unique signature compared with continents that formed later in geologic time.

James continues to investigate the origin of the continental lithosphere and how processes of continental formation and growth have changed over time. He is currently planning a major experiment with DTM colleague Richard Carlson and others to determine how a large and entirely new block of continental lithosphere was created in central and eastern Oregon over the past 20 million years.

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