Founded in the 1960s, the laboratory of Derek York (1936-2007) was a major centre for innovation in the study of Potassium-Argon (K-Ar) dating.
The K-Ar radioisotope dating method can be used to date minerals up to 4.3 billion years old. This makes it invaluable, for instance, in the study of extraterrestrial minerals to better understand the evolution of the solar system.
Born in the UK, York studied physics at Oxford, where he helped to establish the first K-Ar dating laboratory in the UK. In 1960, he was recruited to the University of Toronto following a meeting with the geophysicist J. Tuzo Wilson. Over a long career, he was involved in a variety of projects from the study of lunar and extralunar material returned by the Apollo missions to the dating of fossilized “Lucy” (Australopithecus afarensis) skeleton.
Over decades of work, York and his collaborators revolutionized the process of K-Ar dating at least twice. A few artifacts remain to tell that story.
Professor Derek York (second from the right) in his lab circa 1991.
MS-10 Mass Spectrometer from York Lab (1960s)
In the 1960s, Derek York’s laboratory revolutionized the K-Ar dating process using this simple mass spectrometer.
When Potassium-Argon dating was developed over the early 1950s, the process depended on highly specialized, custom built mass spectrometers made of glass. In the early 1960s, Derek York’s laboratory demonstrated that reliable results could be produced using an AEI MS-10, a relatively inexpensive commercial mass spectrometer designed for use as a leak detector. This discovery made the process considerably more accessible to researchers, greatly accelerating its adoption.
This is the original MS-10 on which that discovery was made. In November of 1997, the artifact was loaned to Margarita López, a former graduate student of York, at CICESE (Centro de Investigación Científica y de Educación Superior de Ensenada) in Ensenada, Baja California. Dr. Lopez graciously returned the artifact in 2022.
Target Vacuum Chamber and Sample Material (c. 1990s)
The laser step-heating process, developed in the 1990s at Derek York’s laboratory, significantly increased the efficiency of the K-Ar process.
The laser step-heating process developed at Derek York’s laboratory involves first irradiating a mineral sample to transform potassium into the isotope argon 39. An area of the sample is then exposed to a laser beam that increases in intensity in discrete steps. With each step, argon 39 and 40 are released until the point at which the release stops and a plateau age is reached.
This technique combined a series of prior innovations (notably the transition to Ar-Ar dating, the use of lasers to release trapped argon, and step-heating) into an efficient and automated process.
The items shown here include a laser target vacuum chamber, as well as sample holders and a mineral sample with laser melting points.