Frank Spear has lifted the field of metamorphic petrology from a largely static, classification-intensive field to one focused on quantitative determination of dynamic orogenic processes, providing a direct link between mineral parageneses and tectonism. Through his written contributions, not only in numerous, highly cited journal articles but also through foundational books and broadly available computational tools, Frank has created a lasting legacy for all researchers interested in the reworking of crust and creation of continents.

Many of the advances in metamorphic petrology can be traced back to Frank’s contributions, including quantitative major and trace element thermobarometry with rigorous evaluation of errors, thermodynamically based determination of pressure-temperature paths, petrochronology of accessory minerals for determining temperature-time histories, kinetics of mineral growth, and implications of local reactions for thermodynamic models. When coupled with other geochronological tools, Frank’s contributions allow us to develop detailed pressure-temperature-time histories of tectonic events. Although founded in geochemistry and petrology, Spear’s work interfaces directly with geophysical modeling, and indeed, many geophysical modelers justify their research on this basis. He has also selflessly provided computational materials to the public and reference materials at low cost; has supported numerous students, postdocs and visiting scientists; and has received diverse scientific, teaching and education awards.

—Frederick Ryerson
Lawrence Livermore National Laboratory
Livermore, California