Ian McDougall 1935–2018

Abstract

Ian McDougall was a renowned Earth scientist who gained worldwide distinction for his research in the fields of K-Ar and 40Ar/39Ar geochronology. He was born in Hobart, Tasmania and obtained a BSc (Hons) at the University of Tasmania and a PhD at the Australian National University in Canberra. Following his PhD, he was introduced to the emerging field of K-Ar geochronology during a postdoctoral year at the University of Berkeley in 1961. On his return to Australia, Ian accepted a position in the newly established K-Ar laboratory at the Australian National University. He pioneered the application of the K-Ar dating method to young volcanic rocks and played a pivotal role in developing the geomagnetic timescale. These findings provided crucial evidence in support of the ‘hot spot’ (mantle plume) model and the emerging theory of plate tectonics. He subsequently established the 40Ar/39Ar geochronology method at the Australian National University and gained an international reputation for meticulous experimental work. In the 1980s, he resolved a significant controversy with regard to the age of hominin fossils and artefacts in the Turkana Basin, Kenya. Over the following four decades, he developed a comprehensive geochronological framework for volcanism across the Turkana Basin, providing the basis for current interpretations of early human evolution in the region. Other notable collaborative accomplishments include the application of the 40Ar/39Ar method to thermal history studies and noble gas geochemistry studies of volcanic glasses and mantle material, which provided insights into the evolution of Earth’s atmosphere and interior. Ian’s scientific contributions were recognised with numerous honours and awards, including being elected a Fellow of the American Geophysical Union, a Fellow of the Australian Academy of Science, and receiving the Jaeger Medal from the Australian Academy of Science and the Centenary Medal for ‘service to Australian society and science in geochronology’.