the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 13 Jan 2026
Extraction of multiple ages from c-axis projected fission tracks
Abstract. The traditional fission track age equation accurately calculates the cooling age for apatite minerals when the cooling rate is fast. Nevertheless, it is used when the cooling rate is gradual, for example when the age of transition through the partial annealing window is to be estimated. Added age information is here obtained by inclusion of the length distribution of fully included near horizontal tracks. The tendency that the shortest tracks are the oldest ones, and the longest ones are the youngest enables the age dating of a given track by counting the number of shorter tracks, adding one, and dividing by the volumetric track generation rate. The difficulty is that the track length–age relation is blurred by the spread in lengths due to crystallographic anisotropy and observational uncertainties. The blurring can be reduced by mathematical deconvolution in which the blurring of tracks in annealing experiments is used. Previously developed equations are updated to improve precision. This paper presents a method where deblurring is first performed by projecting the observed track lengths on the mineral c-axis and then by deblurring using probabilistic least squares inversion. This leads to the extraction of several track ages with deviations for each deconvolved track length histogram. This information may be used to constrain the timing of tectonic events and provide the basis for calculation of past temperature.
-
Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
-
Preprint
(1165 KB)
-
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1165 KB) - Metadata XML
- BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-6510', Raymond Donelick, 11 Feb 2026
- AC1: 'Reply on RC1', Peter Klint Jensen, 04 Mar 2026
-
RC2: 'Comment on egusphere-2025-6510', Anonymous Referee #2, 14 Mar 2026
The manuscript in its current form is approximately four pages long, excluding tables and figures. In several instances, I found it necessary to move back and forth between the manuscript, Appendix A, and Jensen and Hansen (2021) in order to understand the procedures being applied. Readers who are not already familiar with Jensen and Hansen (2021) may experience difficulty following the nodding process and the deconvolution approach used in this study.
In its present form, the manuscript resembles a short communication or technical note rather than a full research article. The author presents only three case studies based on data previously published in another study, and much of the methodological foundation appears to have already been described in Jensen and Hansen (2021).
Nevertheless, the approach itself is interesting and potentially valuable. The work could be suitable for publication; however, in my opinion, it would be appropriate for a short communication or a technical note.
The manuscript would benefit substantially if the author could expand the number of deconvolution examples using datasets from previously published studies. This would help demonstrate the broader applicability and robustness of the method.
In addition, the etching of tracks in apatite is known to be anisotropic. Several factors, such as track thickness, the number of surface tracks intersecting a confined track, light source preferences during observation, and the targeted number of confined track length measurements, can influence the maximum and minimum lengths observed within a confined track length population. These aspects are not mentioned or discussed in the current manuscript. If the author considers these factors to be non-trivial, it would be valuable to address them in the discussion section.
Line 17: Fission track age equations
Comment: The title of this section is “Fission track age equations”. Yet, there is only one equation given in the section.
Line 18: The traditional fission track age equation (Kohn et al., 2024)
Comment: 2024 is a bit too recent to be called traditional, I suppose. Which exact equation is being referred to here? It would be good to add this “traditional equation” in the text, maybe with slightly older reference, where it was first introduced.
Line 22: … anneraling window from 120 C to 60 C…
Comment: Please add reference(s) for this.
Line 23: … included near horizontal fission tracks.
Comment: what is near horizontal? >10degrees? Or 15? Or whatever the analyst sees near horizontal?
Line 26: The starting point is the randomly fully included oriented non-etched fission track in minerals….
Comment: I could not understand what was being said here.
Line 27: The tracks are generated through time, and the length is shortened as a function of time so that ideally the oldest tracks are the shortest ones and the more recent tracks are longest ones.
Comment: This would be partially true for unetched latent tracks in an isotropic system. The tracks are affected by the temperature through the time, the word temperature is missing in this sentence. If the author mentions apatites, the problem would be that this statement is not really right due to anisotropy. If this statement is on etched fission tracks, there are also some parts missing in this statement. How about the proximity to the surface and the number of intersecting tracks? They all contribute to the length.
Line 36: Instead, it is therefore practice making them visible in the light microscope by etching (Kohn et al., 2024)
Comment: Etching is mentioned here for the first time. I assume the text on tracks discussed above are on latent tracks? The reader may easily get disconnected from the text flow.
Line 39: Due to various biases and uncertainties (Ketcham, 2005) the observed track length histogram of etched tracks is blurred
Comment: Which biases and uncertainties?
Line 65: The columns of the deconvolved track length histogram (Fig. 1B) are converted to equivalent time intervals (Fig. 1C) using Eq. (A18).
Comment: Where is equation a18? It would be better to place it right here instead of making the reader wander through supplementary files.
Citation: https://doi.org/10.5194/egusphere-2025-6510-RC2 - AC2: 'Reply on RC2', Peter Klint Jensen, 19 Mar 2026
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-6510', Raymond Donelick, 11 Feb 2026
- AC1: 'Reply on RC1', Peter Klint Jensen, 04 Mar 2026
-
RC2: 'Comment on egusphere-2025-6510', Anonymous Referee #2, 14 Mar 2026
The manuscript in its current form is approximately four pages long, excluding tables and figures. In several instances, I found it necessary to move back and forth between the manuscript, Appendix A, and Jensen and Hansen (2021) in order to understand the procedures being applied. Readers who are not already familiar with Jensen and Hansen (2021) may experience difficulty following the nodding process and the deconvolution approach used in this study.
In its present form, the manuscript resembles a short communication or technical note rather than a full research article. The author presents only three case studies based on data previously published in another study, and much of the methodological foundation appears to have already been described in Jensen and Hansen (2021).
Nevertheless, the approach itself is interesting and potentially valuable. The work could be suitable for publication; however, in my opinion, it would be appropriate for a short communication or a technical note.
The manuscript would benefit substantially if the author could expand the number of deconvolution examples using datasets from previously published studies. This would help demonstrate the broader applicability and robustness of the method.
In addition, the etching of tracks in apatite is known to be anisotropic. Several factors, such as track thickness, the number of surface tracks intersecting a confined track, light source preferences during observation, and the targeted number of confined track length measurements, can influence the maximum and minimum lengths observed within a confined track length population. These aspects are not mentioned or discussed in the current manuscript. If the author considers these factors to be non-trivial, it would be valuable to address them in the discussion section.
Line 17: Fission track age equations
Comment: The title of this section is “Fission track age equations”. Yet, there is only one equation given in the section.
Line 18: The traditional fission track age equation (Kohn et al., 2024)
Comment: 2024 is a bit too recent to be called traditional, I suppose. Which exact equation is being referred to here? It would be good to add this “traditional equation” in the text, maybe with slightly older reference, where it was first introduced.
Line 22: … anneraling window from 120 C to 60 C…
Comment: Please add reference(s) for this.
Line 23: … included near horizontal fission tracks.
Comment: what is near horizontal? >10degrees? Or 15? Or whatever the analyst sees near horizontal?
Line 26: The starting point is the randomly fully included oriented non-etched fission track in minerals….
Comment: I could not understand what was being said here.
Line 27: The tracks are generated through time, and the length is shortened as a function of time so that ideally the oldest tracks are the shortest ones and the more recent tracks are longest ones.
Comment: This would be partially true for unetched latent tracks in an isotropic system. The tracks are affected by the temperature through the time, the word temperature is missing in this sentence. If the author mentions apatites, the problem would be that this statement is not really right due to anisotropy. If this statement is on etched fission tracks, there are also some parts missing in this statement. How about the proximity to the surface and the number of intersecting tracks? They all contribute to the length.
Line 36: Instead, it is therefore practice making them visible in the light microscope by etching (Kohn et al., 2024)
Comment: Etching is mentioned here for the first time. I assume the text on tracks discussed above are on latent tracks? The reader may easily get disconnected from the text flow.
Line 39: Due to various biases and uncertainties (Ketcham, 2005) the observed track length histogram of etched tracks is blurred
Comment: Which biases and uncertainties?
Line 65: The columns of the deconvolved track length histogram (Fig. 1B) are converted to equivalent time intervals (Fig. 1C) using Eq. (A18).
Comment: Where is equation a18? It would be better to place it right here instead of making the reader wander through supplementary files.
Citation: https://doi.org/10.5194/egusphere-2025-6510-RC2 - AC2: 'Reply on RC2', Peter Klint Jensen, 19 Mar 2026
Peer review completion
Journal article(s) based on this preprint
Viewed
| HTML | XML | Total | BibTeX | EndNote | |
|---|---|---|---|---|---|
| 1,106 | 387 | 134 | 1,627 | 129 | 155 |
- HTML: 1,106
- PDF: 387
- XML: 134
- Total: 1,627
- BibTeX: 129
- EndNote: 155
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
Peter K. Jensen
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1165 KB) - Metadata XML
See attached pdf.