the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 25 Nov 2025
Atmospheric 10Be from Talos Dome (East Antarctic) ice core records geomagnetic dipole intensity from 170 to 270 ka BP
Abstract. We present high-resolution 10Be concentration and flux records from the Talos Dome ice core (East Antarctica), covering the period from 170 to 270 ka BP, to assess the capacity of Antarctic ice cores to capture the dipole moment reductions triggered by geomagnetic excursions of different amplitudes. Three distinct geomagnetic events are identified in the 10Be flux. The dipole collapse linked to the Iceland Basin Excursion (IBE) is clearly recorded as a 10Be peak flux 1.59 to 2.08 times above background between (192.0 ± 1.4) ka BP and (185.6 ± 1.4) ka BP. A clear asymmetric structure is observed, with a rapid decline of the geomagnetic dipole, followed by a three-step recovery. Two dipole decreases of lower amplitude are also resolved in relation with the Pringle Falls Excursion (PFE), lasting from (218.5 ± 1.90) to (206.0 ± 0.8) ka BP, and the Mamaku Excursion (ME), identified at (242.0 ± 0.3) ka BP, both showing an increase of the 10Be flux by a factor of 1.24 to 1.63. A total of 52 short-term 10Be concentration minima were also identified and are consistently associated with peaks in major ion concentrations, indicating post-depositional effects that affect concentration but not the longer-term flux signal. Comparison with Dome Fuji ice core and oceanic authigenic 10Be/9Be records reveals strong agreement in the timing and structure of the dipole moment collapses linked with these excursions. These results further support the use of 10Be for synchronizing ice and marine archives as well as to reconstruct past geomagnetic dipole moment variations and refining age models over the Pleistocene.
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Status: open (until 06 Jan 2026)
- RC1: 'Comment on egusphere-2025-5707', Anonymous Referee #1, 30 Dec 2025 reply
Data sets
TALDICE 10Be and major ions 1470-1531 m Alexis Lamothe et al. https://doi.org/10.5281/zenodo.17433638
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- 1
The manuscript presents a new ice core record from Talos Dome, Antarctica, covering the period from 170 to 270 ka BP. This 10Be record is highly significant and provides valuable insights into geomagnetic field variations, including one well-defined global excursion and several others of moderate intensity. The study is thorough, containing extensive information on 10Be measurements, as well as climate proxies and ion concentrations, which are used to assess postdepositional effects and accurately estimate the 10Be flux. The resulting signal is consistent with data from the Dome Fuji ice core, sediment archives, and global production reconstructions based on the VADM stack.
It is important to clarify the reference background to which the results are reported. Discuss the possible options in a single section, and rather than reporting multiple values for one event, decide on one reference value. For example, the background, 1.36, 1.44 or 1.56 x10^5 at cm^-2 a^-1, is over which period, mean, or estimated over the running mean, before or after excluding the identified 10Be minima? (Lines 280 to 293, 349 to 350)
Line 80: Several geomagnetic excursions are reported (Figure 1), but the caption reads three. It would be beneficial to provide a table, either in the main text or in the Supplementary Material, listing the records plotted, including their references. Additional columns could indicate which excursion is recorded and, potentially, the corresponding age. I assume the authors already have this information, as the studies are discussed in Section 2.
From a point a view of the geomagnetic field, the authors discussed variations derived from the PISO-1500 RPI stack. A global model of IBE exists, though outdated, and built with limited, hemispherically-constrained sediment records (Lanci et al. 2008, doi: 10.1016/j.pepi.2008.06.004), the dynamics of IBE can be compared with the TALDICE record. As well as with the global stacks of Frank et al., 1997 (https://doi.org/10.1016/S0012-821X(97)00070-8)
General comment on using brackets when reporting ages and standard deviation on the age? Why? If it is the journal rule ok, otherwise the text will be cleaner without, and removing them improves readability in my opinion (throughout the whole text). The same comment applies to the values of the 10Be/9Be ratio, 10Be half-life (e.g., line 187), and all other numbers in brackets.
Minor comments and questions:
Line 30: Add a reference for the first sentence. E.g., Bono et al., 2022 (doi: 10.1029/2022GL100898)
Line 34: the geodynamo
Line 38: I wouldn't say ‘occasionally conflicting’, rather ‘with high uncertainties’
Line 46: Add ‘e.g.’, in front of references, as these are examples.
Line 47: decreases in plural and (recovery) in the brackets in singular. I understood what the sentence says, but it can be clearer.
Line 48: (ref)?
Line 49: another word for migration?
Line 51: We don’t know if the IBE is probably the strongest. By which criteria? It is probably among the strongest.
Line 53: reduction in % with respect to what? Present-day values?
Line 59: Better make two sentences. It is produced in the atmosphere … 10Be mainly results …
Line 59: too many brackets: .. in the stratosphere, from 60% to 66% (refs)
Line 64: remove the comma before that
Line 65: studies = records
Line 73: avoid double brackets, e.g., … events such as the Laschamps, ~41 ka BP (ref) and
Line 74: The Pringle Falls also named Mamaku or Jamaica? As written so far, Pringle Falls and Mamaku are two separate events?
Line 77: add reference for the sedimentary, as it is given for the other record used for comparison from Dome Fuji.
Line 111: Stoner et al., 1998 is not in the References
Line 113: remove ‘on’
Line 125: an RPI
Line 338: PISO-1500
Line 141/142: Reference only once, as it is the same.
Line 155: Section name: ‘Material, methods and chronology’, as the chronology is a Subsection in this Section
Line 165/175: Only suggestion: Can these long links be removed from the main text and added in the Acknowledgment section, where the institutes and facilities are listed anyway again?
Line 167/168: repetition with Line 178 about the cutting/melting.
Line 173: … developed by Raisbeck et al., 2006 and Baroni et al., 2011. Cite without the brackets, and avoid repetition.
Line 177: remove ‘the’ in front of the number of samples. The number is introduced for the first time here.
Line 177: Why is the standard deviation reported like this? If it is important to report that this is one standard deviation, then: 121+-10 g (1 \sigma).
Line 184: in a crucible
Line 187: The ratio is unitless, right? On this line, and the rest of the text
Line 198: then shared for analysis ..., Please clarify whether ‘shared’ means that different measurements were performed in different laboratories, or that the same measurements were carried out on the same samples for inter-laboratory comparison.
Line 200: What is MSA?
Line 209: The AICC2023 chronology (Bouchet et al., 2023) was used to date
Line 210: Make a new sentence ‘The mean snow accumulation is 5.5 cm a-1’, and move it to Line 212 after the range of accumulation rates is listed, and before the sentence starting with ‘On average, …’
Line 233: Maybe not refer to Figure 5 here because the figure comes much later.
Line 240: moving is more commonly used than rolling
Line 234: Why 0.2 in Eq. 1?
Line 235: The paragraph starting here should be moved later when the comparison is discussed
Line 240: the sentence to be clearer, e.g., ‘3 ka rolling average of the standard deviation’. Suggestion: These 10Be minima were identified when the concentration fell below the mean minus one standard deviation, both calculated using a 3 ka moving window. (If this correctly explains how the minima were identified)
Line 280: rolling again? If you decide to change it in the first place, change it accordingly
Line 245: Add the MIS periods mentioned here on top of Fig. 2?
Line 246: Refer to Fig. 2D
Line 281: Testing 1 ka, 3 ka …
Line 284: To avoid figure reference and citation together. Suggestion: ‘The resulting 3-ka averaged 10Be flux record can be compared to geomagnetic reconstructions, including the Dome Fuji ice core data (Horiuchi et al., 2016) in Figure 4, and authigenic 10Be/9Be records from marine sediment cores (Simon et al., 2016), and the 10Be production (Poluianov et al., 2016) calculated from RPI-based VADM (Channell et al., 2009) in Figure 5.
Line 288: too many brackets
Line 289: After the discussion on the baseline, decide on one and report the enhancement factors with respect to the selected one. Maybe also add the enhancement with respect to the present-day values?
Line 340: running median.
Line 340: ‘similar to’ not ‘similar than’. rolling mean average? Suggestion: ‘During glacial periods, the median method results in 10Be fluxes similar to those obtained using a running mean (Figure S2).’
Line 341: I thought the running median and mean are both calculated on the minima identification results, or not? The sentence is confusing
Line 353: … age models, AICC2023 for TALDICE (Bouchet et al., 2023) and the Dome Fuji DFO-2006 chronology (Kawamura et al., 2007).
Line 359: over which period?
Line 363: .. over the last millennium, between 1000 and 1885 CE, where the …; and only 'CE' not 'a CE'
Line 366: remove brackets around Supplementary material, separate with a comma.
Line 367: remove brackets of the citation, separate with a comma.
Line 368: list the solar minima intervals
Line 384: … in an Antarctic ice core over the period from 170 to 270 ka BP.
Line 385-389: needs to make clear that this interpretation is based on 10Be,
Line 386: It is difficult to say ‘slightly higher’ because it depends a lot on the reference background, as the authors already discussed. I agree with ‘comparable’.
Line 407: (Figure 4) not (Figures 2, 4 and 5)
Line 410: mirrors? I would use another verb. ‘Mirrors’ as ‘reflects’ in terms of slow decrease during the M/B reversal and rapid decrease in excursions, or as ‘reproduces, resembles’, the same behavior? My understanding is the first one, but it could be misinterpreted
Line 415-417: Great point!
Line 418: remove the four brackets in this line, and in the paragraph
Line 422, 1) the ages come with large uncertainties, 2) do we expect excursions to occur at the same time globally, considering the geomagnetic field dynamics?
Line 449: in agreement with PISO-1500 variations
Line 450: Isn’t it the case that for excursions, i.e., enhancements, the only variations that should be interpreted are those in the flux, not in the concentration? What does it mean if the others are not expressed in the concentration?
Line 463: interstadial stages of MIS 7 (7.1 for IBE, ..), Line 400: interglacial MIS 7.1? I believe my confusion here comes because I don’t have expertise in paleo(climatology). Please explain: interstadial vs interglacial in terms of short/long, warm/cold, between/within glacial period. I think it is important to know the climate conditions when these excursions happened.
Line 509: add the age of the Mid-Pleistocene Transition
Line 511: Using the VADM reconstruction PISO-1500 (Channell et al., 2009)
Line 520: This study presents a high-resolution 10Be flux record from the East Antarctic TALDICE ice core, covering the interval from 170 to 270 ka BP, and evaluates the reliability of 10Be as a paleomagnetic proxy and as a tool for synchronizing the chronologies of different proxy archives. (or something along these lines, so the three following points are summarized, not only the first two)
Line 545: .. offer great possibility for cross-checking the chronologies ...
Feedback on the figures:
Figure 1: Capital letter in the caption. Expand the caption. The three excursions, which one?
Figure 2 caption: shaded in black? Are these visible? Explain \deltaD. I found the notations for the subfigures in the brackets confusing. It is much clearer to have: A) …. B) …. etc, as it is started, then continue for C), D), and add E). Write the name of the RPI stack. Y-axis is reversed. Note the MIS stages at the top
Figure 3: Capital letter in the caption. Shaded orange and grey, do these overlap? In total, they should be 52, or 52 orange only? Note down in the caption which ones are removed in the analysis? List the major ion concentration (…).
Figure 4: Capital letter in the caption. Which line is purple? .. the snow accumulation rate. Also, rather than the vertical lines showing the x-axis major ticks, add minor x-axis ticks only to the x-axis, and add vertical lines that distinguish the periods of rapid decline and the three-step recovery (and four arrows showing the decline and recoveries). I would suggest adding another panel showing the Laschamps excursion, as there is an extended discussion on it (with similar vertical lines).
Figure 5: Note the IBE, PFE and ME in the figure on top of the grey bars. Denote the subfigures A,B,C... and add these to the main text when referring to the subfigures. The timing of the stars in TALDICE is also different in MD05-2920, but the sediment record wasn’t considered for defining the shifts, right? Are the stars from TALDICE directly applied to the 10Be global production? I found the star around 210 ka very difficult to uniquely identify.