Application of Thermochronology to Geologic Problems: Bedrock and Detrital Approaches

Abstract

Low-temperature thermochronology can be applied to a wide range of geologic problems. In this chapter, we provide an overview of different approaches, underlying assumptions and suitable sampling strategies for bedrock and detrital thermochronologic analyses, with particular emphasis on the fission-track (FT) method. Approaches to bedrock thermochronology are dependent on the goals of the project and the regional geologic setting, and include application of: (i) multiple methods (e.g., FT, (U--Th)/He and U--Pb) on various mineral phases (e.g., apatite and zircon) from the same sample, (ii) single methods on multiple samples collected over significant relief or across a geographic region (regional approach) or (iii) multiple methods on multiple samples. The cooling history of rock samples can be used to constrain exhumation paths and provides thermochronologic markers to determine fault offset, timing of deformation and virtual tectonic configurations above the present-day topography. Detrital samples can be used to constrain erosion patterns of sediment source regions on both short-term (103--105 yr) and long-term (106--108 yr) timescales, and their evolution through time. The full potential of the detrital thermochronology approach is best exploited by the integrated analysis of samples collected from a stratigraphic succession, samples of modern sediment and independent mineral fertility determinations.