Apatite Fission-Track Analysis

Abstract

Apatite fission-track (AFT) analysis has been widely used during the past 30+ years to constrain the low-temperature thermal histories of many igneous, metamorphic and sedimentary rocks in a wide range of geological settings. Applicable geological settings include orogenic belts, rifted margins, faults, sedimentary basins, cratons, and mineral deposits. The types of geologic problems that can be addressed include the timing and rates of tectonic events, sedimentary basin evolution, the timing of hydrocarbon generation and ore mineralization, the absolute age of volcanic deposits, the effects of major climatic changes on the near-surface geothermal gradient, and long-term landscape evolution. Early work by Naeser (1967) and Wagner (1968, 1969) first established the basic procedures that enabled the fission-track dating method to be applied routinely to these geologic problems. Fleischer et al. (1975) summarized the early studies of the broader discipline of nuclear-track detection in different solid-state materials. More recent comprehensive overviews of fission-track applications have been provided by Naeser and McCulloh (1989), Wagner and Van den haute (1992), Gallagher et al. (1998), Van den haute and De Corte (1998), Dumitru (2000), and Gleadow et al. (2002). Etched, natural fission tracks in several apatite grains are shown in Figure 1⇓. Successful AFT analysis is limited by the following: 1) the availability of apatite from which useful AFT data can be obtained, often due to a lack of apatite of sufficient grain size and quality within available rock types, or, alternatively, the lack of available rock samples due to minimal outcrop exposure or other reasons, 2) economic considerations in terms of the time and money required to obtain sufficient AFT data, 3) the inherent limitations of AFT data to resolve geological thermal history information, often related to limited numbers of accumulated spontaneous fission tracks due to …