Surface paleothermometry using low-temperature thermoluminescence of feldspar

Biswas, Rabiul H.; Herman, Frédéric; King, Georgina E.; Lehmann, Benjamin; Singhvi, Ashok K.

doi:https://doi.org/10.5194/cp-16-2075-2020

Articles | Volume 16, issue 6

https://doi.org/10.5194/cp-16-2075-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/cp-16-2075-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 16, issue 6

Research article

|

04 Nov 2020

Research article |

| 04 Nov 2020

Surface paleothermometry using low-temperature thermoluminescence of feldspar

Rabiul H. Biswas, Frédéric Herman, Georgina E. King, Benjamin Lehmann, and Ashok K. Singhvi

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Final revised paper (published on 04 Nov 2020)
Supplement to the final revised paper
Preprint (discussion started on 11 Feb 2020)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review', Anonymous Referee #1, 24 Mar 2020
- AC1: 'Response to Referee #1', Rabiul Haque Biswas, 03 May 2020
RC2: 'review for "Surface paleothermometry using low temperature thermoluminescence of feldspar"', Anonymous Referee #2, 09 Apr 2020
- AC2: 'Response to Referee #2', Rabiul Haque Biswas, 03 May 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (13 May 2020) by Alberto Reyes

AR by Rabiul Haque Biswas on behalf of the Authors (24 Jun 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (04 Jul 2020) by Alberto Reyes

RR by Anonymous Referee #1 (05 Aug 2020)

Suggestions for revision or reasons for rejection

General comments:

The authors have done a thorough job of clarifying most of the issues I introduced in my initial review. The revised manuscript is easier to follow and more impactful.

In keeping with my earlier review (and in agreement with the other reviewer's two initial points) I view that the kinetics underlying feldspar TL are still ambiguous and that the approach taken here, of treating temperature bin ranges as independent thermochronometers with isolated kinetic parameters, is not ideal. Like the other reviewer rightly pointed out, the compound nature of the feldspar glow curve implies that even the narrowest bin comprises emissions of multiple stabilities. That said, a satisfactory unified model for feldspar TL isn't agreed upon yet, and the authors have made clear their methodology, so I think their approach is acceptable.

I have a few outstanding comments listed below, but in general I think this study is in good shape and should prove to be an valuable resource for the community.

Specific comments:

2/36ff:
To my earlier comment that it would be neat to relate activation energy to rho' via the alpha term, what I meant was that the same rho (dimensional) should pertain and you can use

alpha = 2*sqrt(2*[mE^*]*E)/hbar

to evaluate the value of rho (dimensional), since E and rho' are known for all bins and all other values are fixed and known.

To my comment about thermal loss at room temperature, I understand that previous studies have dedicated separate terms to thermal and athermal loss components, but my question was whether signal loss at RT is negligible, assuming only the 'thermal loss' term. It would be simple to test this by simulation by using the best fit parameter values, populating the traps, turning off the athermal term and seeing whether the signal decreases at T=20C.

If this turns out to be negligible, then all is fine, but if loss does occur, the fading data should be evaluated in terms of both loss pathways simultaneously.

10/14: The revised statement that "At those depths [of 7 and 62 cm] the rock temperature will be at equilibrium with the atmospheric temperature (Hasler et al., 2011)" is still problematic and in conflict with the cited paper. For example, Fig. 8 in Hasler et al. (2011) shows a strong temperature gradient for many sites down to ~1 m.

Likewise, the Magnin paper shows a clear and pronounced temperature gradient extending beyond 2 m, with the exception of the cracked rock, which is cooled by ventilation.

So, a sample taken from 7 or 62 cm will likely not record the same temperature as the atmospheric temp. This is a difficult problem and one that doesn't necessarily need to be solved here, but the text should be straightforward about this complication.

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ED: Publish subject to minor revisions (review by editor) (17 Aug 2020) by Alberto Reyes

AR by Rabiul Haque Biswas on behalf of the Authors (26 Aug 2020) Author's response Manuscript

ED: Publish as is (27 Aug 2020) by Alberto Reyes

AR by Rabiul Haque Biswas on behalf of the Authors (14 Sep 2020) Manuscript

Short summary

A new approach to reconstruct the temporal variation of rock surface temperature using the thermoluminescence (TL) of feldspar is introduced. Multiple TL signals or thermometers in the range of 210 to 250 °C are sensitive to typical surface temperature fluctuations and can be used to constrain thermal histories of rocks over ~50 kyr. We show that it is possible to recover thermal histories of rocks using inverse modeling and with δ18O anomalies as a priori information.