Diffusion chronometry of volcanic rocks: looking backward and forward

Diffusion of elements that result in compositional zoning in minerals in volcanic rocks may be used to determine the timescales of various volcanic processes (e.g., residence times in different reservoirs, ascent rates of magmas). Here, we introduce the tool and discuss the reasons for its gain in popularity in recent times, followed by a summary of various applications and some main inferences from those applications. Some specialized topics that include the role of diffusion anisotropy, isotopic fractionation by diffusion, image analysis as a tool for expediting applications, and the sources of uncertainties in the method are discussed. We point to the connection between timescales obtained from diffusion chronometry to those obtained from geochronology as well as various monitoring tools. A listing of directions in which we feel most progress is necessary/will be forthcoming is provided in the end.