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TitleSimulating sedimentary burial cycles: I. investigating the role of apatite fission track annealing kinetics using synthetic data
AuthorMcDannell, K TORCID logo; Issler, D RORCID logo
SourceGeochronology vol. 3, 2021 p. 321-335, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200758
PublisherCopernicus Publications
Mediapaper; on-line; digital
File formatpdf
Subjectssedimentology; cyclic sedimentation; apatite; fission tracks; models; sedimentation models
Illustrationsgraphs; plots; histograms
ProgramGEM2: Geo-mapping for Energy and Minerals Western Arctic-Beaufort-Northern Yukon
Released2021 05 25
AbstractAge dispersion is a common feature of apatite fission track (AFT) and apatite (U-Th)/He (AHe) thermochronological data and it can be attributed to multiple factors. One underappreciated and underreported cause for dispersion is variability in apatite composition and its influence on thermal annealing of fission tracks. Here we investigate, using synthetic data, how multikinetic AFT annealing behaviour (defined using the rmr0 parameter) can be exploited to recover more accurate, higher resolution thermal histories than are possible using conventional interpretation and modelling approaches. Our forward model simulation spans a 2 Ga time interval with two separate heating-cooling cycles and generates synthetic AFT and AHe data for three different apatite populations with significantly different annealing kinetics. The synthetic data are used as input for inverse modelling (Bayesian QTQt model) that attempts to recover thermal history information under various scenarios. Results show that essential features of the dual peak thermal history are captured using the multikinetic AFT data alone, with or without imposed constraints. Best results are achieved when the multikinetic AFT data are combined with the AHe data (using varying rmr0 values from the AFT data for the He radiation damage model) and constraints are included. In contrast, a more conventional monokinetic interpretation that ignores multikinetic AFT behaviour yields incorrect thermal solutions that fail to adequately reproduce all the data. The AFT data are reproduced well but the AHe data are not. Under these conditions, incorporation of constraints can be very misleading and fail to improve model results. In general, a close fit between observed and modelled parameters is no guarantee of a robust thermal-history solution if data are interpreted incorrectly. For the case of overdispersed AFT data, it is strongly recommended that elemental data be acquired to investigate if multikinetic annealing is the cause of the age scatter. A future companion paper will explore multikinetic AFT methodology and application to detrital apatite samples from Yukon, Canada.
Summary(Plain Language Summary, not published)
Synthetic apatite fission track (AFT) thermochronology data of known characteristics are used for an inverse modelling scheme that illustrates how detailed thermal history information can be recovered from multikinetic AFT data and how erroneous histories can result if standard interpretation and modelling approaches are used instead. The new method exploits the variation in detrital apatite mineral chemistry within a rock sample to define separate AFT populations that are sensitive to different parts of its thermal history. A second paper will discuss multikinetic AFT interpretation and modelling techniques using real data from the Yukon.

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