ESR-thermochronometry of the MIZ1 borehole, Tono, Japan

King, Georgina E.; Bossin, Lily; Bernard, Maxime; Kranz-Bartz, Melanie; Wen, Xiaoxia; Schmidt, Christoph; Guralnik, Benny; Herman, Frédéric; Ogata, Manabu; Sueoka, Shigeru

doi:10.5194/egusphere-2026-2204

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https://doi.org/10.5194/egusphere-2026-2204

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23 Apr 2026

| 23 Apr 2026

ESR-thermochronometry of the MIZ1 borehole, Tono, Japan

Georgina E. King, Lily Bossin, Maxime Bernard, Melanie Kranz-Bartz, Xiaoxia Wen, Christoph Schmidt, Benny Guralnik, Frédéric Herman, Manabu Ogata, and Shigeru Sueoka

Abstract. The electron spin resonance (ESR) of quartz can be used as a low temperature thermochronometric system, however, to date no field validation of the approach has been made. Here we explore the ESR signals of quartz from six samples from the MIZ1 borehole (Tono, Japan). Previous studies have shown that this low-relief region underwent Quaternary exhumation at rates of <0.2 mm yr^-1. We investigate whether quartz ESR signals can resolve such low rates of exhumation, or whether the samples are in thermal equilibrium with ambient borehole temperature. ESR thermochronometry requires that both sample-specific signal saturation and thermal decay are constrained in the laboratory, which makes measurements highly time-consuming. To overcome this, the development of a standardised growth curve (SGC) was explored, which allowed more rapid constraint of the trapped-charge concentrations of each of the samples. Thermal kinetic parameters were determined using an isothermal decay experiment for each individual sample and except for sample MIZ1-08, it was possible to fit all the isothermal decay data together to yield a single set of kinetic parameters that successfully described the dataset. The ESR thermochronometry results show that the MIZ1 samples are in thermal equilibrium for the Al-centre, and that Monte-Carlo inversion of the ESR data yields present-day borehole temperature within 1σ uncertainties for all samples except the lowest temperature sample. In contrast, inversion of the different Ti-centre options (A, B, D) yields temperatures 15–20 °C above contemporary borehole temperature, indicating rock cooling equivalent to a total exhumation of ~1 km over the same period. The cause of this discrepancy is unclear but may relate to sub-linearity of Ti-centre dose response, that led to underestimation of the trapped-charge concentration and hence an overestimation of borehole temperature. Our results validate ESR-thermochronometry of the Al-centre and show that an SGC and common thermal kinetic parameters may be used to expediate sample measurements, however ESR-thermochronometric data from the Ti-centre should be used cautiously until further validation data are available.

Received: 17 Apr 2026 – Discussion started: 23 Apr 2026

Competing interests: At least one of the (co-)authors is a member of the editorial board of Geochronology.

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Georgina E. King, Lily Bossin, Maxime Bernard, Melanie Kranz-Bartz, Xiaoxia Wen, Christoph Schmidt, Benny Guralnik, Frédéric Herman, Manabu Ogata, and Shigeru Sueoka

Status: final response (author comments only)

RC1:
'Comment on egusphere-2026-2204', Erick Prince, 26 May 2026
Dear authors,
I enjoyed reading your manuscript entitled “ESR-thermochronometry of the MIZ1 borehole, Tono, Japan”. I consider it is a well-polished, rigorous, easy to follow, and concise article, that presents an important advance in the field of ESR thermochronometry to validate the method using modern samples. This had not been previously achieved to the degree presented in the paper.
The manuscript fits well within the scope Geochronology, presenting novel data and concepts for the validation of the method. The presented methodology is sound, the results clearly support the interpretations, and the conclusions are substantial. In general, the text is well-structured and fluent, though a few sentences in very specific places could be rearranged for clarity. While the description of experiments and calculations is mostly transparent, I have asked for clarifications in a few steps to ensure full traceability. The largest issues I found were that the supplementary tables are missing from the file, and the inconsistent use of the different functions to fit the dose response curve data.
Upon detailed examination, I have noted a few minor points which are noted in the comments below. These comments are rather aimed at improving the manuscript or raised out of scientific curiosity. I also suggested a few additions to the supplementary figures, as mentioned in my comments, that could be helpful to strengthen the arguments. Therefore, I recommend this article for publication in Geochronology following the respective minor revisions.
Point-by-point comments:
Line 89: Is it also the exact same set of samples from Ogata et al (2022)? If that is the case, I think this could be openly stated in the text

Line 139: The term “annealing” is often used in geology, rock mechanics, and other thermochronometry systems for the temperature dependent process by which damage in the crystal lattice is either partially or completely erased through thermal diffusion. I understand that this is different for the OSL/ESR community, but I would suggest rephrasing the term to another more descriptive such as “thermal reset”. This would be more appropriate considering that for ESR dating we are usually vacating the electrons from the traps instead of healing the defects. This term is also used in line 142 and 146, but there might be other instances that I missed.

Line 141-142: Out of curiosity. Why were the aliquots heated for a longer period than that used for the SAR protocol? Would there be a chance that the prolonged heating also changes the sensitivity?

Line 145-146: I have the same question here about the heating time at 400C. To keep things comparable, is it not better to always use the same duration?

Line 145-148: The information about the model to fit the data from the experiment could be directly mentioned here.

Line 153: How were the natural signals normalized? This is important for the interpretation of the trend.

Line 158-159: I think the curve fitting to the different functions should be mentioned in the methods. It is not common to see the exponential+linear fit in addition to the saturated exponential. Therefore, I think a short explanation of why both fits were used would be helpful. The process for the estimation of the De could also be shortly explained there.

Line 164-165: Could this variance in the Ti data be related to the chosen preheat temperature? Is there any data from an isochronal pulse annealing test available?

Line 168-170: How was the ratio calculated?

Line 175-181: While I agree that the curves displayed in Fig 2 are very similar, it is hard to see it in the current version of the figure. The chosen shapes of the markers produce an overlap in the data points, and on top of that, the plots are also relatively small. I also have concerns about the chosen scale for the axis. I think presenting the curves using a log scaling is a clever way to show the overall trend reaching high doses, but I also think it could mask the shape of the curves at lower doses. I think it would be interesting to see in the supplements all these curves without the log() scaling. In addition, the confidence intervals for each curve fit could be included. I think this might further strengthen the argument about the curves having the same shape. The same goes for Fig 3.

Line 185-205: Was the arbitrary irradiation dose for the normalization one of the irradiation steps for each curve? For the De values mentioned in lines 198-205. Are these the ones calculated from the SSE? It is unclear because of the first sentence of the paragraph. If these are from a single fit, why were the De from the other fit disregarded? I think for Fig 3 the comment I made about Fig 2 is relevant too, especially for panels c and f. Including the confidence intervals for the fit in a curve that is not transformed to logarithm, and showing how the De were calculated could help to understand the variability that is described in the text.

Line 195: The fits referred to in this sentence are hard to see in the respective figure.

Line 215: Up until this point, the article uses two functions for the dose response curve. Why is only SSE considered from this point onwards? I think specifying the reason could be helpful for future studies trying to apply the standardized growth curves or in general just to fit the data.

Line 222-223: How was the thermal lifetime calculated?

Line 295: I think it would be important to mention the calculated values in the text here.

Line 300-306: The specific figures and tables could be explicitly cited again in their respective sentences across the text.

Line 304-306: I think here it would be worth discussing why only the SSE fit was considered.

Line 307-312: Another question out of curiosity. Were the models also compared to other kinetic models such as GOK? If that is the case, what were the temperatures?

Line 335-337: The sentence is a bit convoluted and the meaning is unclear.

Line 380: Could the discrepancy in the Ti center also result from the models that we use for the thermal decay kinetics?

Line 381: Do you consider that standard growth curve could work well if the origin of the quartz grains has different sources? Or would it be recommended to apply this method only if the source is relatively homogeneous?

Figures:
In general, figures could be a bit larger. In addition, some of the markers are large and partially overlap which makes it difficult to observe the data in detail. All of this especially affects figures 1 to 4.
Figure 1: What are the black and white markers representing in panels a and b? This is clear in the caption but not directly in the figure.
Figure 2: Are the uncertainties from the measurements included in the plotted data?
Figure 5: The inset in panel b is not legible.
Figure 6: I recommend placing a title on the columns to make the figure intuitive upon a first glance. The figure is also cut on the left margin.
Tables:
The supplementary tables are missing from the file and inaccessible elsewhere.
Technical/Writing:
Line 48-50: The way the information is presented makes it a bit unclear whether the region underwent the exhumation or just the borehole.

Line 31: For completeness, I think it would be worth specifying that the doses are irradiation doses. Similarly, “We seek to exploit this” could be completed as “We seek to exploit this characteristic”.

Lines 43-45: I suggest changing the first “because” to make the sentence less repetitive.
Citation: https://doi.org/10.5194/egusphere-2026-2204-RC1
RC2: 'Comment on egusphere-2026-2204', Pierre Valla, 04 Jun 2026

Dear Authors, dear Editors,
Please find below my evaluation concerning the revised manuscript by King and co-authors entitled "ESR-thermochronometry of the MIZ1 borehole, Tono, Japan" (manuscript 2026-2204). First of all, I sincerely apologize for the delay in sending my evaluation.
This manuscript investigates the potential of quartz ESR thermochrometry using a nice dataset from a borehole in Japan (MIZ1). This is a perfect setting to approach methodologically the validation and application of ESR thermochronometry, since the lithology is relatively uniform and the setting offers slow exhumation over long term. The authors provide a large analytical dataset to describe the signal acquisition and saturation, as well as signal stability, concentrating on common Al and Ti centres. They then propose inverse modeling of their dataset to discuss the sensitivity of the different signals to ambient borehole temperature and/or limited exhumation. Their results show nicely that Al-centre signals do allow to retrieve thermal steady-state in the borehole, while the Ti-centre signal appears more difficult to interpret in terms of thermal steady-state or colling signal. The authors finally propose potential explanations and future directions to explore for this apparent mismatch and further validate the use of quartz ESR for thermochronometry.
The manuscript is well written and nicely illustrated, with several supplementary figures and the available dataset online. Only the supplementary tables are missing from the submission files, so this would be needed in the revisions since key analytical data are present. The analytical approach and strategy are well described, this is sometimes less clear for the signal acquisition (individual dose-response curves, SAR vs. SAAD, and standardised growth curve with/without preheat), I would encourage the authors to re-organize slightly this part and try to rely on figures for clarity (see my specific comments for details). I think this is a great contribution for the ongoing development of ESR thermochronometry, and will be of interest for the readership of G-Chron and beyond.
I have further detailed below my questions and suggestions in a set of general comments and more specific comments.
General comments:
- Data presentation: as stated above, supplementary tables are missing which is needed to evaluate all the analytical work conducted and the output results. Furthermore, section 4.1 is dense and sometimes difficult to follow given the different tests/approaches conducted in this work. I would suggest to slightly re-organize the results to better communicate (the links between text and figures is sometimes not clear), and to really guide the reader where to check the output data (figures, supp. figures or tables). For some results, and afterwards in the numerical inversion, some choices have been made to emphasize the SSE model for signal growth and the Ti-D signal compared to DSE model and Ti-A/-B, respectively. I agree with the authors’ choices, but I think this needs to be clearly stated and justified why they followed this strategy.
- Thermal decay and data inversion: the section 4.2 on thermal decay is relatively short, and I would encourage the authors to expand the result presentation and discussion. For instance, one sample (MIZ1-08) is considered as outlier but it is difficult to evaluate to what extent, and also how do the individual vs. common data fitting compare and perform for data inversion. Similarly, data inversion has been done considering (1) thermal steady state or (2) random cooling histories. An intermediate scenario could have been to consider the previously-constrained exhumation rate of the area (0.16 km/Myr) to perform data inversion, or alternatively to discuss the outcomes of random cooling histories in terms of literature estimates. I guess this could be really interesting for readers.
Specific comments, by line number:
- Line 11 “no field validation of the approach”. Maybe rephrase to be more explicit, some ESR thermochrometric data have already been proposed for boreholes or field samples, as presented in the introduction.
- Line 12. Maybe specify there that the lithology is overall uniform in the MIZ1 borehole.
- Line 19. "single set of kinetic parameters that successfully described the dataset". Provide some numbers there for readers? Or equivalent closure/retention temperature for Al/Ti signals?
- Line 21. “lowest temperature sample”. Maybe shallowest sample would read better.
- Line 23. “1 km over the same period”. Which period? Unclear please rephrase.
- Lines 30-31. Maybe some references could help there for introducing the ESR method. Same comment for line 33 on thermochronometry, some general references could help the readers.
- Line 37. Maybe also add King et al., 2020 for the previous studies on ESR thermochronometry.
- Lines 30-40. I would suggest to add few lines in the introduction about the different Al/Ti signals, their saturation/intensity characteristics and potential kinetic parameters (thermal behavior). That may help the readers to follow the methodological approach afterwards.
- Line 43. “benchmark results”. Maybe add “analytical” for clarity.
- Line 48; “existing thermochronometric data are available”. Please provide more details there, high or low temperature systems, which ones and what are results?
- Line 53. “consistent with previous data”. Which data, the Quaternary exhumation rates? Please clarify.
- Lines 61-62. The lithology slightly differs (different granite types) for the investigated samples, maybe add some discussion on that point for the ESR data?
- Line 72. “indicative of a low rate of rock exhumation”. Is there a maximum estimate on this exhumation rate (and over which period?) from Ogata et al., 2022?
- Line 76. “fluid in the borehole”. Water circulation? Or something else?
- Line 81. “borehole temperatures are sensitive to surface temperature fluctuations”. Over which depth? Are all surface samples potentially affected? Please provide some numbers if possible.
- Line 89. What was the original sample sizes? Cuttings or cores? This can be interesting for readers having access to borehole samples.
- Line 106. What are the different A, B, D options for Ti signal? Please provide some explanations for readers, and I would suggest to move figure S1 from supplementary to the main text to show the ESR spectra and indicate where are located Al and Ti signals.
- Line 110. Unclear how many aliquots were measured for preaheated or non preheated protocols. Please clarify in text and/or Table 1.
- Line 115. “into saturation which occurred at ~60 kGy for the Al-centre and ~7 kGy for the Ti-centre”. Can the reader see this on a figure?
- Line 118. “De values”. These are not reported in the Table 1 (only n/Nat and apparent ages), maybe add De values too?
- Line 124. “environmental dose rate”. What is the grainsize used for quartz dose rate? Is it evaluated from thin section (ie before crushing)? The Table S3 is not accessible so this is difficult to check, and also some details in the main text would be important for readers.
- Line 128 and 130. “section 3.1”. Isn’t it section 4.1?
- Lines 131-134. Maybe add “apparent” for ages, and there are some commas (De column). Two questions for this table: why only option D for Ti signal is shown? And what are “All” lines, mean of all samples or alltogether-inversion? This could be specified in the caption for clarity.
- Lines 139-141. Not really clear on which figures one can see those results, maybe point to figures or supp. figures.
- Line 142. “were annealed for 90 min at 400 °C prior to irradiation with 1,030 Gy and measurement in a SAR protocol either with or without preheating.”. Sorry I am not sure I got this sentence, the aliquots were annealed so what is the point of the preheating or not there? Maybe provide more details there, I may have missed something.
- Line 153. “multiple aliquots were measured for individual samples”. Unclear please clarify (see also my previous comment), are there several aliquots for each sample? It is unclear on figure 1 if the different points are different aliquots or protocols (different signals, preheat/ no preheat).
- Line 168. “dose-recovery test was done using two aliquots of two samples; one aliquot of each sample was preheated, whilst the other aliquot was not preheated”. For all signals or only Al and Ti-D?
- Line 181. “the SAAD dose response curve is fitted for curve extrapolation, i.e. <4.5 kGy.”. This choice is difficult to get, and to visualize since the DRCs on figures 2-3 are given in log scale, so the 4.5kGy is really the beginning of DRC or even not visible on the figures? The x-axis starts at 4 (log scale), so only visible on figure S2? Please provide more details there for clarity.
- Line 184. Figure 2: why are DRCs for Ti-centre ramping and decreasing at very high doses? Is it normal (quenching is mentioned afterwards)? Please provide some explanation for non experts of ESR method, since it appears impossible to fit these DRCs with SSE or DSE right?
For figure 2, 3 and S3-4, what are start symbols representing? It is mentioned “SAAD+SAR De” but this is unclear to me sorry.
- Line 202-203. “using the SGC, or where the SGC is truncated to an arbitrarily selected maximum dose of 4.5 kGy before fitting, the deviation reduces to <15 % for most samples”. Again this step is difficult to follow, please point to figure(s) where we can visualize this for clarity.
- Line 208. “for the Ti-…”. Please specify that only option D is shown there, and refer to supp. figures for options A-B (Fig. S4?).
- Line 210. Specify that both SSE and DSE are shown in figure 3e,f, then why only SSE is used afterwards (see my general comment on this).
- Line 216. Please point to figure 3c,f for this observation.
- Lines 219-225. This section is rather short and could be expanded. What is the fitting procedure for the data, Monte-Carlo sampling (what initial ranges of parameters) and how are fits accepted/rejected? Please also provide in this section the ranges of inverted parameters for individual and common fitting procedures (Table 1).
- Line 225. Figure 4: what is the observed data variability for 160°C isothermal decay? Is it a specific sample? Also, how different is MIZ108, from Table 1 the kinetic parameters are not apparently so different, no? Please provide more details in this section 4.2 and show individual isothermal decay data in supp for clarity.
- Line 229. Have the authors tested to invert independently all samples with their own DRC and isothermal decay data? I appreciate the strategy presented here, but is it entirely valid compared to independent inversions? That would be great to show/discuss this point.
- Line 230. “assuming single-saturating exponential growth”. Why is only SSE considered there, and not DSE anymore? Please clarify.
- Line 232. “isothermal histories over 40 Ma with temperatures between 0 and 80 ºC.”. This is a fair strategy before testing random thermal histories (next step), but why not testing a simple linear cooling rate for 0.16km/Ma exhumation rate (from previous data)? Please discuss this point maybe.
- Line 235. “the Ti-centre (Option D)”. Why only the option D is considered there? I can see the choice but this needs to be specified and explained/discussed, see my general comment.
- Line 238. Figure 5: For panel b, what is then the effect of PH/noPH on inverted temperatures? This point is not discussed in the text, please provide some details.
For panel b, it is unclear what is the inset (I guess zoom in of the main figure with dashed box?) and what are the different lines (model for different times?) and stars? Please clarify. And this panel is not discussed/presented in the main text (or I missed it). Finally, panel c is only presented in the discussion section, maybe quickly present it in section 4.2.
- Line 263. I am wondering how the output thermal histories do compare (or not) with the previously-proposed exhumation rates of 0.16 km/Ma. Can the authors provide some details and discussion, this is I think interesting no?
- Line 279. “was small BIC”. BIC needs to be explained for readers.
- Line 280. “main difference is found for the tail of the isothermal decay curves…”. Not entirely sure, there is also a difference for the early part of the decay curve from fig. S9, no? Please check and discuss in case.
- Line 284. Quenching is only mentioned now, and not when presenting the DRCs if Ti signal (Figures 2-3). Please consider adding some explanation before for readers.
- Line 295-298. Why is this section on closure temperature not presented before together with inverted borehole temperature?
- Line 299. The discussion is not really easy to follow, maybe structure it with subsections?
- Line 308. “except MIZ1-08”. Why is this sample different? From table 1 it does not appear so different for kinetic parameters, and data are not presented nor discussed for this sample. Please consider adding some further information.
- Line 310. “similar lithology”. From borehole description there are two different granites, maybe discuss this point and that there is no influence on ESR data (which is an interesting outcome).
- Line 326. “0.11-0.20 mm/yr”. Have the authors tried to inverse (or forward) model their ESR data with this exhumation rate, to see whether the data are in agreement with it?
- Line 330. “the non-preheated”. The results have not been presented before on Figure 5a.
- Line 332. “discrepancy between the two aliquots is unclear but may be related to preheating”. And so what would be the authors’ recommendation, also when including/discussing the existing literature for ESR (dating and/or thermochronometry)?
- Lines 344-346. These statements are interesting and may also be mentioned already in the introduction, no?
- Line 350. “all options for the Ti-centre”. Have the authors also performed data inversion for options A and B? If yes then this would be interesting to show them in the supp.
- Line 356-357. “given their similar thermal stability”. I agree from the authors’ results, but has this been already proposed for previous studies? If I don’t mistake, in Wen et al. 2024 the Ti and Al signals have apparently quite different thermal stabilities, no? Please discuss this point.
- Line 363. “may relate to irradiation or heating-induced sensitivity change throughout measurement, that could not be successfully monitored”. Is it something related to quenching but at lower doses? Or alternatively the different Ti sensitivity can be related to another process, geological, that was not captured by laboratory analyses?
- Line 367. “OSL-thermochronometry”. Please add “feldspar” for clarity. Also for line 371.
- Line 369. “lower closure temperature”. Can we talk about closure or retention temperature there?
- Line 371. “10 °C/Myr”. Isn’t it lower, more to 4-5 °C/Myr? Please check.
- Line 372. Maybe add “quartz” for clarity.

Supplementary information:
- Supplementary tables S1-S4 are missing from the file.
- Figure S1: Maybe show on figure the Al and Ti peaks, and indicate in caption the range of regenerative doses. Also I wonder if this figure could be moved to main text for clarity?
- Figure S2: this is difficult to link this figure with figures 3-4 in the main text, since the x-axis scale is different (below 4000Gy there, above 10000 Gy in main text). Also, why only SSE is shown here and not DSE?
- Figure S5: maybe specify “SAR” for x-axis of the different panels. And I didn’t get the difference between A and C, or B and D, this is not explicit in the caption. Please clarify.
- Figure S9: why is this only shown for Ti-D and not for Al centre, as a comparison?
- Figure S10: values for prior and posterior should be reversed no? 2740Gy for posterior, and 3820 Gy for prior?
- Figure S11: the modeling is performed with different kinetic (bant tail vs. gauss) models for feldspar OSL and quartz ESR data, can this partly explain the different retention (I prefer this term as closure, maybe correct in caption) temperatures shown there? Please consider extending this discussion point in the main text.

I hope these comments and suggestions may be useful for revising this manuscript and main conclusions, and I look forward to seeing it published.
Sincerely,
Pierre Valla
(Grenoble, 3 June 2026)

Citation: https://doi.org/10.5194/egusphere-2026-2204-RC2

Georgina E. King, Lily Bossin, Maxime Bernard, Melanie Kranz-Bartz, Xiaoxia Wen, Christoph Schmidt, Benny Guralnik, Frédéric Herman, Manabu Ogata, and Shigeru Sueoka

Supplement

https://doi.org/10.5194/egusphere-2026-2204-supplement

Georgina E. King, Lily Bossin, Maxime Bernard, Melanie Kranz-Bartz, Xiaoxia Wen, Christoph Schmidt, Benny Guralnik, Frédéric Herman, Manabu Ogata, and Shigeru Sueoka

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Short summary

Electron spin resonance (ESR) thermochronometry can be used to determine rock temperature changes, which occur as rocks move towards Earth's surface in response to uplift and surface erosion. We use samples from a known-temperature borehole to validate the method, by constraining the thermal sensitivity of quartz ESR signals in the laboratory. Whilst we are able to recover temperature successfully with the Al-centre signals, the Ti-centre signals overestimate the borehole temperature.


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