Mid-Holocene Climate Record in Santovka Travertine (Slovakia) and regional Biases of Climate Shifts 8.2 and 7.4 ka BP

Petřík, Jan; Adameková, Katarína; Kele, Sándor; Milovský, Rastislav; Petr, Libor; Tóth, Peter; McKay, Nicholas

doi:https://doi.org/10.5194/egusphere-2023-118

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https://doi.org/10.5194/egusphere-2023-118

Preprints

07 Mar 2023

| 07 Mar 2023

Mid-Holocene Climate Record in Santovka Travertine (Slovakia) and regional Biases of Climate Shifts 8.2 and 7.4 ka BP

Jan Petřík, Katarína Adameková, Sándor Kele, Rastislav Milovský, Libor Petr, Peter Tóth, and Nicholas McKay

Abstract. The study of freshwater carbonates, such as travertines and speleothems, provides valuable insights into the regional biases of mid-Holocene climate development in Central-Eastern (CE) and South-Eastern (SE) Europe. The formation of a lake in the travertine deposition system of the Santovka site, located at the transition of the Western Carpathians and the Pannonian Basin, has led to the preservation of a valuable record. We analyzed the litho- and microstratigraphy, chemical composition, including δ¹⁸O and δ¹³C stable isotopes, and geochronology of the Santovka-village section. We then compared these palaeoclimatic records with reference records from Central-Eastern and South-Eastern Europe in terms of significant climate shifts. The prevalent part of the section studied, which spans between 8200 and 6400 cal BP, is represented by fluvial/fluvio-lacustrine sediments and lake marl. The 8.2 ka BP event was only detected in the δ¹³C record from the nearby Santovka-PB section. However, we found an abrupt change in both isotopic records around 7400–7200 cal BP, which is likely connected to increased detrital input and some minor palaeoecological changes in the Santovka-village section. These changes are most likely associated with the drying of the lake. The 8.2 event in Central-Eastern (CE) and South-Eastern (SE) Europe is well reflected in the δ¹³C records, while the change in δ¹⁸O was insignificant. In contrast, the newly suggested climate shift around 7400–7000 ka BP was detected at most sites in both δ¹⁸O and δ¹³C records. This development could be connected to a change in air mass circulation, synchronous with declining solar irradiance and increased evidence of drift ice in the North Atlantic.

Received: 30 Jan 2023 – Discussion started: 07 Mar 2023

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Jan Petřík, Katarína Adameková, Sándor Kele, Rastislav Milovský, Libor Petr, Peter Tóth, and Nicholas McKay

Status: closed

RC1:
'Comment on egusphere-2023-118', Anonymous Referee #1, 31 Mar 2023

The manuscript contains an interesting compilation of isotopic data from genetically different carbonates from sites in central Europe. The authors try to explain both the differences and similarities between the records and explain the changes in isotope values.
In my opinion, the text needs further attention before publication.
My most crucial concerns are carbonates and their genesis. What is the genesis of carbonates? Carbonate concretions, rounded and angular micritic and sparitic carbonate clasts, are mentioned, which are not listed in Table 1. Later in the text, travertine lake sediment is mentioned. I am concerned by the influence of the detrital input on your stable isotope data. What was the composition of the detrital material? Did it contain carbonates? In lines 361-362 a suggestion of the detrital origin of carbonates is provided! Genesis of the carbonates is critical in terms of stable isotope study. If carbonates' origin changed during the sediment sequence deposition in question, how can the stable isotope record be applied in the palaeoenvironmental study?
Genetically different carbonates are compared. Is it possible that the divergences result from the genesis of the carbonates?
The text, mainly fragments describing lithology and sedimentary setting, contains inconsistencies and interpretations not proven by facts. Most of them are listed below.
In the Abstract, two different ways of presenting dates are used, and I suggest standardising.
41 - (HCO) is not an abbreviation of Holocene thermal optimum.
41-42 – ‘the 8.2 ka BP event and was followed by a return to climatic conditions typical of the Holocene thermal optimum (HCO)’. – In central Europe, temperatures were still increasing before the 8.2 ka (e.g. Kaufmann et al. 2020); therefore, you cannot say about a return, but rather of a break in the increasing trend.
41-42 – what do you mean by ‘The mid-Holocene development …’? Mid-Holocene climate changes?
45 – North Atlantic Ocean
46-48 – you should start with a suggestion that other records of climate changes are needed and then discuss the potential of stable isotopes; otherwise, isotopes turn out of the blue
49 – ‘These records …’ – specify what records you have on your mind
50 – ‘air flow’ change to ‘air masses’
63-63 – this sentence should be incorporated in the next paragraph; also, what is meant by ‘sedimentological setting’? Conditions of sedimentation? Also ‘extra-sedimentological parameters’ sound enigmatic
69 – I guess information about an enhanced age-depth model is not needed here
77 – ‘mean annual δ18O value varies around −9.19 ‰’ – either indicate the range or the mean:
‘δ18O value varies between … and …’
‘mean annual δ18O value is −9.19 ‰’
78 – change ‘surroundings’ to ‘bedrock’
80 – why ‘sufficiently’?
83 – what is a ‘mineral spring’? why not simply ‘a spring’?
86 – I suggest changing to: ‘temperature of the spring water’
Caption to Fig 1 – how about adding references to the sites listed in the caption?
116 – delete ‘stratigraphic’
120-121 – ‘We revised the same samples in terms of geochemical analyses to obtain concentrations of missing chemical elements.’ – what do you mean by revised? You took samples for chemical analysis from the same sediment samples sampled before? Maybe simply – ‘resampled’? Also, ‘missing’ is not an appropriate word here, rather, you supplemented the geochemical study of the sediments.
121 & 138 – what is meant by carbonate concretion? Concretions are often postdepositional, which would exclude their use in this study. Possibly concretion is not appropriate term here.
146 – I suggest simply – chronology
149 – what is meant by ‘enhanced age-depth model’?
163 – change ‘found in’ to ‘from’
163-166 – I suggest to add names of the sites here since they are referred to later in the manuscript
178 and below – the sediment sequence was investigated previously; did the previous study include the characterisation of lithology? If so, I suggest referring to the previous study and mentioning only the facts essential for the interpretation.
180 – ‘belong to the part of interest’ change to ‘are the subject of research in this paper’
184 – ‘Units 6a and 6b …’
184 – here and later, and also in Table S1 you mention mollusc shells, plant remains etc. Did you study those, or the data come from a published paper? This must be indicated.
184 – in table S1 there is no information about the difference in mollusc and plant remains in Units 6a and 6b because there is no Unit 6a! Unit 6b is mentioned three times in the table but with no differences between the samples!
189 – what do you mean by ‘precipitated carbonates’?
198 – what do you mean by ‘macroscopically significant organic layer’? Distinctive? Is this information needed?
203 – once again ‘carbonate concretions’ are mentioned. I guess the term used is incorrect. Possibly carbonate precipitates/carbonate grains are meant here?
204 – delete one ‘mainly’
208-209 – which organisms you mean by benthic? Ostracods and molluscs? This should be explained when used for the first time. I found the explanation in line 211 – shift it earlier.
Table 1 – Unit 2c – delete one ‘shells’
Table 1 – Unit 4 – contrary to other units described in Table 1 you do not provide an interpretation of the environment where the sediment was deposited.
Table 1 – Units 6a and 6b – do you mean ‘rounded fragments of travertines’?
Fig 4 caption – stable isotope ratios and concentrations of elements
248 – rather: ‘concentrations of elements’
249 and later – rather ‘concentrations’ than ‘values’
253 – delete ‘organics’, also later in the paragraph
267 and later – ratios, e.g. ‘Mg/Ca ratios …’
269 – maxima
277 – ‘Low values (….) were detected between 240 and 200 cm …’
279 – change ‘A clearly visible’ to ‘An abrupt’
283 – change ‘comes’ to ‘occurs’
Figure 5 – what is marked by red line and grey field? Again – what are carbonate concretions?
292 before and later – change geochronology to chronology
Table 2 should include calibrated ages!
Table 2 – indicate which ages were used in the age-depth model. Mark the one which was not used.
295-296 – why sample 10046 does not occur on the age-depth model? If it was used as you state in the text it should be visible on the model!
326 – what do you mean by ‘mean lines’?
328-329 – are the ages mentioned here calibrated? They should be.
328 – I am not a native speaker but I have doubts whether ‘… shift belongs to the period …’ is correct; ‘the biggest shift is in the period… ‘
329 – BP is missing here
Figure 7 – correct description of axes – do you present calibrated dates? Vertical isotope axis also needs correction
Table 3 – what is travertine lake sediment? In lakes carbonate marl is deposited. The term travertine lake sediment was not mentioned while describing lithology
347-358 – what indicates fluvio-lacustrine sediments, there is no proof of such interpretation in the text; how about mollusc shells – what ecosystem do they indicate?
349 – shift ‘(high LOI, S)’ earlier in the sentence, paste it after ‘sediments’
350-351 – ‘The high concentration of carbonates could be connected with mineral spring activity’ – explain; also why ‘mineral spring’? Was it simply CaCO3 precipitation form spring waters?
354 – what is the evidence for the formation of the travertine mound? Maybe there was a landslide that led to the formation of the lake? Provide appropriate evidence.
356 – why lakes?
357 – maybe better – ‘formation of a shallow lake’
357 – within Unit 6a and 6b molluscs were also present and you described the environment as fluvio, fluvio-lacustrine. Here you say that ‘some aquatic molluscs’ were present in Unit 5 and that the sedimentation took place in a lake. Are the molluscs indicative of environmental change? Probably you should indicate the most characteristic species which prove a change in the ecosystem.
358 – please explain what is a travertine-depositing system? Isn’t it better to name it simply a small lake or a pond?
360 – I am concerned by the influence of the detrital input on your stable isotope data. What was the composition of the detrital material? Does it contain carbonates? In lines 361-362 a suggestion of detrital origin of carbonates is provided!
364-365 – If there was a detrital input, why is increased Si concentration not linked with supply of allochthonous material?
372 – delete the first ‘organic’
373-374 – the paper by Zolitschka et al. 2015 reviews laminated lake sediments formed in deep lakes. In your study, a shallow lake could have formed. What proof do you have for anoxic deposition? Was there a significant supply of organics?
379-382 – data on broadleaf trees provided in the two sentences are contradictory. Whether there was a decline or not?
384 – please be more specific – what is meant by the production of the mineral spring? Why mineral spring, not simply a spring? I guess CaCO3 precipitation from spring waters is considered.
387 – ‘… of benthic species.’ Which one?
389 – ‘water body’ – maybe more simply – ‘a lake’, i.e. the lake still existed but there was a change in sedimentation
398 – do you suggest the detrital origin of carbonates or precipitation from thermal waters? Reading the following lies – from thermal waters. Why δ18O record was not influenced?
399 – citation is lacking after ‘places’
399-401 – it would be good to provide values for comparison here
403 – Pleistocene
405 – Late Glacial
413 – what if the degree of mixing changed in time? The proportions between water from the two sources changed?
425 – development of what?
427 – indicate what C4 vegetation could occur in the region; also a brief explanation how C4 photosynthesis affects δ13C values would be appreciated
440 – delete ‘lasting’
447-448 – it is challenging to compare the data to the ones published by Dabkowski et al. 2019 due to the scarcity of isotopic data from Mituchovce. I guess there are only two values in the period discussed.
449 – dry not drought
452 – explain what do you mean in this sentence?
452 – in lakes diverging δ13C and δ18O records are commonly linked with throughflow conditions, i.e. an open lake
453 – explain how!
453-455 – if you do not have proof, and palynological data shows contradictory results, then delete this suggestion
456 – what can landscape change cause?
Figure 8 – please enlarge descriptions of vertical axes, they are illegible
468 – what you mean by climate development?
471-473 – according to the sentence authors of the manuscript evaluated and recognised the climatic shift in the sequences mentioned, which is not true since this was an achievement of authors of particular studies mentioned. This sentence must be edited to eliminate this misunderstanding
499 – what you mean was probably a change in the circulation, not it development
500 – delete fully – twice
510 – masses of moist air were transported
526 – correct the isotopes in the caption, i.e. δ¹⁸O and δ¹³C
532 – and this is a surprising conclusion, not explained enough in the text; also as indicated in the text and in the following lines of conclusion, the sedimentary environment changed in time; therefore this must have influenced isotope values; δ18O values in carbonates precipitated in fluvial conditions should differ from the ones precipitated in a lake
539 – ‘dip’ is not an appropriate term here
548 – the last sentence of Conclusions should be deleted

Citation: https://doi.org/10.5194/egusphere-2023-118-RC1
- AC1: 'Reply on RC1', Jan Petřík, 28 Apr 2023
  
  Dear reviewer,
  First of all, thank you for thorough reading and in-depth review, which significantly help us to improve the manuscript. We accept and elaborate most of your comments during eventual next phase of submission process. Now I would like to preliminary react and explain your concern about carbonate genesis and origin. You are right, we have to fix terminology, because „concretion“ is not an appropriate term. We deal with subrounded in-situ precipitated carbonate grains/nodules of prevalent micritic microstructure, which more likely precipitated in a carbonate rich lake environment with input of thermal water. These precipitates were extracted from sieved material under binocular microscope. We will describe the process of extraction and selection in the method chapter. We selected only this material to avoid noise in climatic signal. There were also angular travertine fragments in the lowermost unit, which we also avoided. We will provide a more detailed description and interpretation of carbonates nodules/grains in the corrected version of the manuscript.
  We presume presence of some „detrital input“ according to the chemical signal (K, Rb), but optically we detected some quartz, feldspars and volcanic rocks only in the uppermost (unit 2c) and some in lowermost (6b) unit. Thank for this comment. We will surely exclude the unit 2c samples from palaeoclimatological consideration, because this unit is of colluvial origin.
  
  Citation: https://doi.org/10.5194/egusphere-2023-118-AC1
RC2:
'Comment on egusphere-2023-118', Anonymous Referee #2, 05 Apr 2023
Dear Editor, Dear Authors,

Thanks for the invitation for reviewing this (egusphere-2023-118) manuscript. I think it is a data rich study contributing interesting pieces to the mid-Holocene environmental history of the study area. However major revision is needed before the final publication of the study.
My major concern is the paleoclimatological significance of the data (which somehow questioning the fit of the current version of this paper to the scope of CP). I understand and agree that the observed lithological and chemical changes argue for paleoenvironmental changes. This could be climate induced changes but could be local, non-climatic reasons, as well. If I correctly compare the unit borders in Fig4B and the shift positions in Fig7 then the detected shift is at Unit4. Based on the description in 4.1 the lacustrine environment changed from unit 5a and 5b (line 190: “benthic organism remains (mainly diatoms)”) to unit 3 (line 211: “benthic organisms (ostracods prevailing over diatoms”) suggesting that the change in the benthic fauna could be partly (or entirely?) explains the detected isotopic shift.
The occasional correspondence with the presented changes from a set of isotope records collected from the broad surroundings of the studied site do not support a regionally coherent environmental change which could make a solid basis for a paleoclimatic explanation. Authors themselves claim the lack of clear pattern in d¹⁸O shifts among the studied records in line329. (The reader’s impression is that there are only random correspondences between certain local changes which are typically not reflected by the majority of the parallel climate sensitive proxies.) There are minor mistakes or confusing graphical elements in Fig1, Fig3, Fig5. In addition, Fig8, which could be a key figure of the study, in its current layout is practically a random collection of curves.

Although I’ve listed some typos among the technical comments below, I note that I did not correct the English as I am not a native English speaker.

Major points:
I was surprised at how much the introduction overemphasizes the paleoclimatological importance of travertines and tufas in this region. So, I searched a bit both for other potentially available paleoclimate studies and for the cited references (listed in 4 lines from 54 to 57). A first comment is that if I consider paleoclimatological research in general (as the beginning of the sentence of line 53) then I think it is obvious, without any particular justification, that paleoclimatological research was not “mainly conducted on travertines and tufas”. Assuming that the Authors refer with only to the mid-Holocene, as mentioned in the first sentence of the paragraph, some revision is still necessary from two aspects. On the one hand, among the cited articles Demovic et al., 1972 and Gradzinski et al., 2008 do not provide any information regarding paleoclimate (and where radiometric ages are included they do not fall into the mid-Holocene); nor does the abstract content of Vieira et al., 2022 justify that it is must be mentioned among the paleoclimate researches of the region. On the other hand, I feel that the ignoring the paleobiological information available from the vicinity of the research area (few examples: https://doi.org/10.1177/0959683614551225, https://doi.org/10.1016/j.quascirev.2016.04.001, https://doi.org/10.1556/ceugeol.53.2010.1.3) is misleading. Considering some of these records could be more meaningful to take into account in the discussion instead of comparison with a surprisingly remote one like e.g., Grotta di Ernesto ER76.

Please complete the methodological description of the stable isotope analysis fulfilling the minimum requirements for publishing stable-isotope delta results (https://doi.org/10.1515/pac-2021-1108 ) At least two essential info are missing i) the certified values and associated standard or expanded uncertainties of the reference materials and ii) the method used for normalization of stable-isotope measurement.

The description of the litho- and microstratigraphy contains too much sedimentological jargon. I think it is a bit annoying for readers with palaeoclimatological background. If you are dedicated to go for a palaeoclimatological contribution some of the sedimentological description could be expelled to the supplementary.

Finally, a technical comment. The font type is different in some parts of the text. Please check lines 77, 276.

Minor comments:
lines 31-32 Abbreviations of CE and SE have already been introduced in the abstract.
line 41 The bracketed HCO is somehow confusing. Is it an incomplete reference? or a mistyped abbreviation for Holocene thermal optimum? Anyway, the entire sentence needs some revision because Holocene thermal optimum can be found still in the Early Holocene at many sites across the Northern Hemisphere see e.g. https://doi.org/10.1016/j.quascirev.2012.05.022
lines 75-77: Please provide reference period for the presented climatologies.
line 88: Please capitalize Quaternary
line 92: Does it really needed presenting the geographical coordinates with 7 decimal digits? I think 3 digits is enough.
line 96: The last sentence of this section is confusing or at least the meaning is unclear. Do you mean that: The nearest spring (core B-3A), situated circa 100 m from the section, is characterized by a water temperature of 26.6 °C and a mean discharge of 8 L s^-1?
line 141: “…flushed with helium to remove the atmosphere …” It sounds strange. Please rephrase.
lines 152-154: I’m afraid that the current sentence is confusing or unclear. Do you mean the “mean of the age ensemble”?
line 165: Maybe a definite article is needed at the end of the line. I mean: “…in the pre-alpine region…”
line 167: Please delete “glacier”.
line 174: Maybe a definite article is missing also here. I mean: “…of the procedure…”
line 189: “precipitated carbonate” Do you mean autochthonous carbonate?
line 276: “Significantly low values” sounds strange. Maybe simply “Lower values”
line 281: “decrease again up to” sounds strange. Maybe omit “up”
line 359: “The” instead of “the”
lines 371-377: I’m afraid that the proposed ideas cannot explain seasonal anoxic conditions.
line 391: “algaes” sounds like double-plural: I think “algae” is sufficient.
lines 427-430: I cannot see the rationale mentioning C4 plant here. C4 plants could become locally dominant only after maize cultivation spread in this region.
line 448: Add space between till and ca.
line 485: Ascunsa Cave is not in the northern Pannonian Basin.
line 488: Please correct the typo “Ernesto” instead of “Ernestoa”
line 494: I think a definite article is needed before the Carpathians. I mean: “…from the Carpathians…”
line 513: Please correct the typo in citation “Hercman” instead of “Hermcan”
line 514-519: Sorry, but the information provided here (referred to Russo et al., 2022, Park et al., 2019) is not at all linked to the paleoenvironmental changes deciphered from the analyzed record. What do you want to explain with the Arctic amplification, for instance?
Figures
Fig1: Please correct the typo in the map. “Western” instead of “Westhern”
Fig3: Arrows (both yellow and orange ones) should be increased.
Fig4: I cannot see the added value of the smoothing splines. The variance is so faint in the original values. In addition, a common axis label as “numValue” for all horizontal axes is unacceptable. Finally, the caption also needs some revision because LOI is not a chemical element.
Fig5 What is your goal with showing the general form of linear model in the plot? Anyway, is this plot needed at all? There is not any point in the discussion referring to this plot. My impression is that this figure is superfluous.
Fig8: What do you wish to present with this figure? In its current form this compilation of isotope records seems lacking a clear conception. Some annotation could help the reader to understand the climatic meaning of the different proxies (e.g. warm-cold, dry – wet). Some of the low-res records (e.g., Mituchovci, Poleva) hardly show any meaningful variance in this period. I’m afraid that these low-res records only confuse the readability rather than add to this picture. A final technical remark is that it is impossible to spell out the axis labels in the current layout
Citation: https://doi.org/10.5194/egusphere-2023-118-RC2
- AC2: 'Reply on RC2', Jan Petřík, 28 Apr 2023
  
  Dear reviewer,
  Thank you for taking the time to review our manuscript and providing valuable feedback. We are ready to implement most of the suggestions to improve the manuscript and make major revisions. At this point, I would like to address the main concerns and major points raised by the referee. The minor comments will be directly implemented into the next version of the manuscript.
  The isotopic analysis is based on the same carbonate precipitates throughout the section and should be independent of local paleobiological alteration. We argue that local environmental, lithological, and stable isotope record changes were caused by a supraregional climate shift. There is certainly proxy evidence of local change reflected by lithology, physicochemical proxies, and paleobiological proxies (c.f. Šolcová et al. 2018), which are taken into account and discussed. At the same time, this change is more likely associated with the local stable isotope record reflecting climate-hydrology changes, which are primarily influenced by the mean annual isotopic composition of meteoric water and the continentality effect in the case of δ18O and warmer periods (lower δ13C) or colder periods connected with reduced biological and pedological activity in soil (higher δ13C). We found the interpretation of increasing D13C during the detected shift in unit 4/3C (circa 7.3 ka BP) to be challenging, as it could indicate both warming and an increase in humidity. Other evidence (sedimentology, micromorphology) however, indicates drying and a consequent sedimentary hiatus (at least local drying). On the other hand, there is increasing D18O (warming) in the Santovka record and elsewhere. The detected shifts are certainly associated with changes in the local environment, but at the same time, we argue that changes in local conditions were caused by regional/supraregional climate shifts: "It could be partly caused by a change of water regime associated with the disappearance of Búr brook and/or waning of the mineral spring. This change is connected to environmental change recorded in an age-depth model about 7300 cal BP, more likely relating to a shift in climatic conditions".
  We appreciate your concerns regarding the occasional correspondence in D13C records and the potential lack of regionally coherent environmental change. We would like to clarify that the observed pattern in D13C is not a mere coincidence, but rather a repeating pattern in the records we have selected based on pre-defined criteria. Sites were selected according to time span, age, record resolution, geographic position, and data availability (for more details see lines 160-170). Our analysis focused on the recurring temporal pattern of D13C shifts, which we believe is indicative of a significant paleoclimatic phenomenon.
  Regarding the lack of a clear pattern in the δ18O shifts mentioned in line 329, we acknowledge that our initial statement might have caused confusion. We intend to revise this part of the manuscript to emphasize that, despite some inconsistencies, the recurring pattern in D13C records is of primary interest in our study.
  We have chosen the region of Central-Eastern and South-Eastern Europe to investigate changes in the influence of dominant air currents on paleoclimatic records. In order to study sub-millennial variations, we have selected relevant speleothem, lake sediment, travertine, and tufa isotopic records, as published paleobiological studies have few samples and thus insufficient resolution for the paleoclimatic record. That is why we have not used, for example, https://doi.org/10.1016/j.quascirev.2016.04.001.
  We also aimed to broaden the context of our research by correlating with hematite-stained grains in the North Atlantic Ocean (Bond et al., 2001), changes in Total Solar Irradiance (Steinhilber et al., 2009), which temporally fit with the detected climate shift. These proxies could be excluded if they are deemed a random collection of curves. Alternatively, we can further discuss the coincidence with the Sapropel S1 event and changes in salinity in the Marmara Sea and the Mediterranean around 7.5 ka BP (https://doi.org/10.1016/S0031-0182(02)00596-5).
  
  We will also supplement the methodological description of isotopic analysis. We could shorten the sedimentological and micromorphological description and move part of it to the supplementary material. The font type will be unified.
  Thank you once again for your valuable feedback, and we look forward to further improving our manuscript based on your suggestions.
  Sincerely, authors
  
  Citation: https://doi.org/10.5194/egusphere-2023-118-AC2
RC3:
'Comment on egusphere-2023-118', Anonymous Referee #3, 06 Apr 2023
This study reports data on a 2.8 m-high section of carbonate-bearing sediments that the authors describe as “travertine lake represented by lake marl deposits”.
I recommend this ms. to be rejected and submitted to a regional journal, or possibly a palaeolimnological or sedimentary journal, because its climate interpretation is not sufficiently well supported to justify publication in CP.
Here are some suggestions for improvement:
Provide a proper sediment log of this small outcrop, and put Table 1 into the supplement

I got confused about the type of carbonate-bearing sediments studied (travertine, carbonate concretions, marls..). Which type of carbonate is represented by the isotope data?

10 radiocarbon ages (incl. 1 obvious outlier) only provide a moderately well contrained depth-age model, which could/should be improved. E.g., the 8.2 event time window is poorly constrained and hinges on one (the basal) 14C age

Report age model uncertainties when referring to age data in the text

Provide calibrated 14C ages in Table 2

Not clear why the authors measured a number of elemental abundances (which are not really climate-sensitive) but did not include more sensitive proxies such as pollen or diatoms

The English needs some improvement, starting with the title
Citation: https://doi.org/10.5194/egusphere-2023-118-RC3
- AC3:
  'Reply on RC3', Jan Petřík, 15 May 2023
  Dear Reviewer,
  Thank you for your time and detailed feedback on our manuscript. We greatly value your comments and believe they will assist us in improving the quality of our work. Here, we address your specific points:
  
  Following your recommendation, we will revise the sediment log and move Table 1 to the supplementary section.
  
  We apologize for the confusion regarding the type of carbonate sediments studied. We have now improved the petrographic specification of the precipitated carbonates from which the isotope data are derived. We will ensure that this will be clearly articulated in the revised manuscript.
  
  We agree that our depth-age model can be enhanced. However, it should be noted that the model is based on 9 dates and is compiled in a standard manner. It is an improved and supplemented version of an age-depth model previously published. Specifically, the 8.2 event is located between dates UGAMS 10045 and UGAMS 10044 and there is minor deviation without inversion. Hence, we believe that the model is sufficient. Moreover, it is not a black box; we have made the entire code publicly available for reproducibility.
  
  We acknowledge that we should have reported age model uncertainties in the text. This will be rectified in the revised version.
  
  Thank you for pointing out the omission of calibrated radiocarbon data in Table 2. We will correct this oversight.
  
  Your query regarding the measurement of elemental abundances is justified. Paleoenvironmental analyses of pollen, plant macrofossils, and mollusks were conducted in a previous study. More sensitive proxies such as diatoms are a logical next step, and we are eager to perform their analysis in follow-up research.
  
  We apologize for the deficiencies in English. We will focus on language improvement, starting with the title.
  
  Finally, we appreciate your suggestion regarding publication in a regional or paleolimnological journal. However, we believe that our data and interpretations hold relevance for the broader climate science community and can contribute to a better understanding of past climate events. We will strive to make this clearer in the revised version of our manuscript. Moreover, our study has supra-regional significance as we document a climate shift that can be correlated within the Central and Southeastern European region, likely linked with global scale events.
  Thank you once again for your insightful feedback and guidance.
  Best regards,
  
  Jan Petrik
  
  Citation: https://doi.org/10.5194/egusphere-2023-118-AC3

Status: closed

RC1:
'Comment on egusphere-2023-118', Anonymous Referee #1, 31 Mar 2023

The manuscript contains an interesting compilation of isotopic data from genetically different carbonates from sites in central Europe. The authors try to explain both the differences and similarities between the records and explain the changes in isotope values.
In my opinion, the text needs further attention before publication.
My most crucial concerns are carbonates and their genesis. What is the genesis of carbonates? Carbonate concretions, rounded and angular micritic and sparitic carbonate clasts, are mentioned, which are not listed in Table 1. Later in the text, travertine lake sediment is mentioned. I am concerned by the influence of the detrital input on your stable isotope data. What was the composition of the detrital material? Did it contain carbonates? In lines 361-362 a suggestion of the detrital origin of carbonates is provided! Genesis of the carbonates is critical in terms of stable isotope study. If carbonates' origin changed during the sediment sequence deposition in question, how can the stable isotope record be applied in the palaeoenvironmental study?
Genetically different carbonates are compared. Is it possible that the divergences result from the genesis of the carbonates?
The text, mainly fragments describing lithology and sedimentary setting, contains inconsistencies and interpretations not proven by facts. Most of them are listed below.
In the Abstract, two different ways of presenting dates are used, and I suggest standardising.
41 - (HCO) is not an abbreviation of Holocene thermal optimum.
41-42 – ‘the 8.2 ka BP event and was followed by a return to climatic conditions typical of the Holocene thermal optimum (HCO)’. – In central Europe, temperatures were still increasing before the 8.2 ka (e.g. Kaufmann et al. 2020); therefore, you cannot say about a return, but rather of a break in the increasing trend.
41-42 – what do you mean by ‘The mid-Holocene development …’? Mid-Holocene climate changes?
45 – North Atlantic Ocean
46-48 – you should start with a suggestion that other records of climate changes are needed and then discuss the potential of stable isotopes; otherwise, isotopes turn out of the blue
49 – ‘These records …’ – specify what records you have on your mind
50 – ‘air flow’ change to ‘air masses’
63-63 – this sentence should be incorporated in the next paragraph; also, what is meant by ‘sedimentological setting’? Conditions of sedimentation? Also ‘extra-sedimentological parameters’ sound enigmatic
69 – I guess information about an enhanced age-depth model is not needed here
77 – ‘mean annual δ18O value varies around −9.19 ‰’ – either indicate the range or the mean:
‘δ18O value varies between … and …’
‘mean annual δ18O value is −9.19 ‰’
78 – change ‘surroundings’ to ‘bedrock’
80 – why ‘sufficiently’?
83 – what is a ‘mineral spring’? why not simply ‘a spring’?
86 – I suggest changing to: ‘temperature of the spring water’
Caption to Fig 1 – how about adding references to the sites listed in the caption?
116 – delete ‘stratigraphic’
120-121 – ‘We revised the same samples in terms of geochemical analyses to obtain concentrations of missing chemical elements.’ – what do you mean by revised? You took samples for chemical analysis from the same sediment samples sampled before? Maybe simply – ‘resampled’? Also, ‘missing’ is not an appropriate word here, rather, you supplemented the geochemical study of the sediments.
121 & 138 – what is meant by carbonate concretion? Concretions are often postdepositional, which would exclude their use in this study. Possibly concretion is not appropriate term here.
146 – I suggest simply – chronology
149 – what is meant by ‘enhanced age-depth model’?
163 – change ‘found in’ to ‘from’
163-166 – I suggest to add names of the sites here since they are referred to later in the manuscript
178 and below – the sediment sequence was investigated previously; did the previous study include the characterisation of lithology? If so, I suggest referring to the previous study and mentioning only the facts essential for the interpretation.
180 – ‘belong to the part of interest’ change to ‘are the subject of research in this paper’
184 – ‘Units 6a and 6b …’
184 – here and later, and also in Table S1 you mention mollusc shells, plant remains etc. Did you study those, or the data come from a published paper? This must be indicated.
184 – in table S1 there is no information about the difference in mollusc and plant remains in Units 6a and 6b because there is no Unit 6a! Unit 6b is mentioned three times in the table but with no differences between the samples!
189 – what do you mean by ‘precipitated carbonates’?
198 – what do you mean by ‘macroscopically significant organic layer’? Distinctive? Is this information needed?
203 – once again ‘carbonate concretions’ are mentioned. I guess the term used is incorrect. Possibly carbonate precipitates/carbonate grains are meant here?
204 – delete one ‘mainly’
208-209 – which organisms you mean by benthic? Ostracods and molluscs? This should be explained when used for the first time. I found the explanation in line 211 – shift it earlier.
Table 1 – Unit 2c – delete one ‘shells’
Table 1 – Unit 4 – contrary to other units described in Table 1 you do not provide an interpretation of the environment where the sediment was deposited.
Table 1 – Units 6a and 6b – do you mean ‘rounded fragments of travertines’?
Fig 4 caption – stable isotope ratios and concentrations of elements
248 – rather: ‘concentrations of elements’
249 and later – rather ‘concentrations’ than ‘values’
253 – delete ‘organics’, also later in the paragraph
267 and later – ratios, e.g. ‘Mg/Ca ratios …’
269 – maxima
277 – ‘Low values (….) were detected between 240 and 200 cm …’
279 – change ‘A clearly visible’ to ‘An abrupt’
283 – change ‘comes’ to ‘occurs’
Figure 5 – what is marked by red line and grey field? Again – what are carbonate concretions?
292 before and later – change geochronology to chronology
Table 2 should include calibrated ages!
Table 2 – indicate which ages were used in the age-depth model. Mark the one which was not used.
295-296 – why sample 10046 does not occur on the age-depth model? If it was used as you state in the text it should be visible on the model!
326 – what do you mean by ‘mean lines’?
328-329 – are the ages mentioned here calibrated? They should be.
328 – I am not a native speaker but I have doubts whether ‘… shift belongs to the period …’ is correct; ‘the biggest shift is in the period… ‘
329 – BP is missing here
Figure 7 – correct description of axes – do you present calibrated dates? Vertical isotope axis also needs correction
Table 3 – what is travertine lake sediment? In lakes carbonate marl is deposited. The term travertine lake sediment was not mentioned while describing lithology
347-358 – what indicates fluvio-lacustrine sediments, there is no proof of such interpretation in the text; how about mollusc shells – what ecosystem do they indicate?
349 – shift ‘(high LOI, S)’ earlier in the sentence, paste it after ‘sediments’
350-351 – ‘The high concentration of carbonates could be connected with mineral spring activity’ – explain; also why ‘mineral spring’? Was it simply CaCO3 precipitation form spring waters?
354 – what is the evidence for the formation of the travertine mound? Maybe there was a landslide that led to the formation of the lake? Provide appropriate evidence.
356 – why lakes?
357 – maybe better – ‘formation of a shallow lake’
357 – within Unit 6a and 6b molluscs were also present and you described the environment as fluvio, fluvio-lacustrine. Here you say that ‘some aquatic molluscs’ were present in Unit 5 and that the sedimentation took place in a lake. Are the molluscs indicative of environmental change? Probably you should indicate the most characteristic species which prove a change in the ecosystem.
358 – please explain what is a travertine-depositing system? Isn’t it better to name it simply a small lake or a pond?
360 – I am concerned by the influence of the detrital input on your stable isotope data. What was the composition of the detrital material? Does it contain carbonates? In lines 361-362 a suggestion of detrital origin of carbonates is provided!
364-365 – If there was a detrital input, why is increased Si concentration not linked with supply of allochthonous material?
372 – delete the first ‘organic’
373-374 – the paper by Zolitschka et al. 2015 reviews laminated lake sediments formed in deep lakes. In your study, a shallow lake could have formed. What proof do you have for anoxic deposition? Was there a significant supply of organics?
379-382 – data on broadleaf trees provided in the two sentences are contradictory. Whether there was a decline or not?
384 – please be more specific – what is meant by the production of the mineral spring? Why mineral spring, not simply a spring? I guess CaCO3 precipitation from spring waters is considered.
387 – ‘… of benthic species.’ Which one?
389 – ‘water body’ – maybe more simply – ‘a lake’, i.e. the lake still existed but there was a change in sedimentation
398 – do you suggest the detrital origin of carbonates or precipitation from thermal waters? Reading the following lies – from thermal waters. Why δ18O record was not influenced?
399 – citation is lacking after ‘places’
399-401 – it would be good to provide values for comparison here
403 – Pleistocene
405 – Late Glacial
413 – what if the degree of mixing changed in time? The proportions between water from the two sources changed?
425 – development of what?
427 – indicate what C4 vegetation could occur in the region; also a brief explanation how C4 photosynthesis affects δ13C values would be appreciated
440 – delete ‘lasting’
447-448 – it is challenging to compare the data to the ones published by Dabkowski et al. 2019 due to the scarcity of isotopic data from Mituchovce. I guess there are only two values in the period discussed.
449 – dry not drought
452 – explain what do you mean in this sentence?
452 – in lakes diverging δ13C and δ18O records are commonly linked with throughflow conditions, i.e. an open lake
453 – explain how!
453-455 – if you do not have proof, and palynological data shows contradictory results, then delete this suggestion
456 – what can landscape change cause?
Figure 8 – please enlarge descriptions of vertical axes, they are illegible
468 – what you mean by climate development?
471-473 – according to the sentence authors of the manuscript evaluated and recognised the climatic shift in the sequences mentioned, which is not true since this was an achievement of authors of particular studies mentioned. This sentence must be edited to eliminate this misunderstanding
499 – what you mean was probably a change in the circulation, not it development
500 – delete fully – twice
510 – masses of moist air were transported
526 – correct the isotopes in the caption, i.e. δ¹⁸O and δ¹³C
532 – and this is a surprising conclusion, not explained enough in the text; also as indicated in the text and in the following lines of conclusion, the sedimentary environment changed in time; therefore this must have influenced isotope values; δ18O values in carbonates precipitated in fluvial conditions should differ from the ones precipitated in a lake
539 – ‘dip’ is not an appropriate term here
548 – the last sentence of Conclusions should be deleted

Citation: https://doi.org/10.5194/egusphere-2023-118-RC1
- AC1: 'Reply on RC1', Jan Petřík, 28 Apr 2023
  
  Dear reviewer,
  First of all, thank you for thorough reading and in-depth review, which significantly help us to improve the manuscript. We accept and elaborate most of your comments during eventual next phase of submission process. Now I would like to preliminary react and explain your concern about carbonate genesis and origin. You are right, we have to fix terminology, because „concretion“ is not an appropriate term. We deal with subrounded in-situ precipitated carbonate grains/nodules of prevalent micritic microstructure, which more likely precipitated in a carbonate rich lake environment with input of thermal water. These precipitates were extracted from sieved material under binocular microscope. We will describe the process of extraction and selection in the method chapter. We selected only this material to avoid noise in climatic signal. There were also angular travertine fragments in the lowermost unit, which we also avoided. We will provide a more detailed description and interpretation of carbonates nodules/grains in the corrected version of the manuscript.
  We presume presence of some „detrital input“ according to the chemical signal (K, Rb), but optically we detected some quartz, feldspars and volcanic rocks only in the uppermost (unit 2c) and some in lowermost (6b) unit. Thank for this comment. We will surely exclude the unit 2c samples from palaeoclimatological consideration, because this unit is of colluvial origin.
  
  Citation: https://doi.org/10.5194/egusphere-2023-118-AC1
RC2:
'Comment on egusphere-2023-118', Anonymous Referee #2, 05 Apr 2023
Dear Editor, Dear Authors,

Thanks for the invitation for reviewing this (egusphere-2023-118) manuscript. I think it is a data rich study contributing interesting pieces to the mid-Holocene environmental history of the study area. However major revision is needed before the final publication of the study.
My major concern is the paleoclimatological significance of the data (which somehow questioning the fit of the current version of this paper to the scope of CP). I understand and agree that the observed lithological and chemical changes argue for paleoenvironmental changes. This could be climate induced changes but could be local, non-climatic reasons, as well. If I correctly compare the unit borders in Fig4B and the shift positions in Fig7 then the detected shift is at Unit4. Based on the description in 4.1 the lacustrine environment changed from unit 5a and 5b (line 190: “benthic organism remains (mainly diatoms)”) to unit 3 (line 211: “benthic organisms (ostracods prevailing over diatoms”) suggesting that the change in the benthic fauna could be partly (or entirely?) explains the detected isotopic shift.
The occasional correspondence with the presented changes from a set of isotope records collected from the broad surroundings of the studied site do not support a regionally coherent environmental change which could make a solid basis for a paleoclimatic explanation. Authors themselves claim the lack of clear pattern in d¹⁸O shifts among the studied records in line329. (The reader’s impression is that there are only random correspondences between certain local changes which are typically not reflected by the majority of the parallel climate sensitive proxies.) There are minor mistakes or confusing graphical elements in Fig1, Fig3, Fig5. In addition, Fig8, which could be a key figure of the study, in its current layout is practically a random collection of curves.

Although I’ve listed some typos among the technical comments below, I note that I did not correct the English as I am not a native English speaker.

Major points:
I was surprised at how much the introduction overemphasizes the paleoclimatological importance of travertines and tufas in this region. So, I searched a bit both for other potentially available paleoclimate studies and for the cited references (listed in 4 lines from 54 to 57). A first comment is that if I consider paleoclimatological research in general (as the beginning of the sentence of line 53) then I think it is obvious, without any particular justification, that paleoclimatological research was not “mainly conducted on travertines and tufas”. Assuming that the Authors refer with only to the mid-Holocene, as mentioned in the first sentence of the paragraph, some revision is still necessary from two aspects. On the one hand, among the cited articles Demovic et al., 1972 and Gradzinski et al., 2008 do not provide any information regarding paleoclimate (and where radiometric ages are included they do not fall into the mid-Holocene); nor does the abstract content of Vieira et al., 2022 justify that it is must be mentioned among the paleoclimate researches of the region. On the other hand, I feel that the ignoring the paleobiological information available from the vicinity of the research area (few examples: https://doi.org/10.1177/0959683614551225, https://doi.org/10.1016/j.quascirev.2016.04.001, https://doi.org/10.1556/ceugeol.53.2010.1.3) is misleading. Considering some of these records could be more meaningful to take into account in the discussion instead of comparison with a surprisingly remote one like e.g., Grotta di Ernesto ER76.

Please complete the methodological description of the stable isotope analysis fulfilling the minimum requirements for publishing stable-isotope delta results (https://doi.org/10.1515/pac-2021-1108 ) At least two essential info are missing i) the certified values and associated standard or expanded uncertainties of the reference materials and ii) the method used for normalization of stable-isotope measurement.

The description of the litho- and microstratigraphy contains too much sedimentological jargon. I think it is a bit annoying for readers with palaeoclimatological background. If you are dedicated to go for a palaeoclimatological contribution some of the sedimentological description could be expelled to the supplementary.

Finally, a technical comment. The font type is different in some parts of the text. Please check lines 77, 276.

Minor comments:
lines 31-32 Abbreviations of CE and SE have already been introduced in the abstract.
line 41 The bracketed HCO is somehow confusing. Is it an incomplete reference? or a mistyped abbreviation for Holocene thermal optimum? Anyway, the entire sentence needs some revision because Holocene thermal optimum can be found still in the Early Holocene at many sites across the Northern Hemisphere see e.g. https://doi.org/10.1016/j.quascirev.2012.05.022
lines 75-77: Please provide reference period for the presented climatologies.
line 88: Please capitalize Quaternary
line 92: Does it really needed presenting the geographical coordinates with 7 decimal digits? I think 3 digits is enough.
line 96: The last sentence of this section is confusing or at least the meaning is unclear. Do you mean that: The nearest spring (core B-3A), situated circa 100 m from the section, is characterized by a water temperature of 26.6 °C and a mean discharge of 8 L s^-1?
line 141: “…flushed with helium to remove the atmosphere …” It sounds strange. Please rephrase.
lines 152-154: I’m afraid that the current sentence is confusing or unclear. Do you mean the “mean of the age ensemble”?
line 165: Maybe a definite article is needed at the end of the line. I mean: “…in the pre-alpine region…”
line 167: Please delete “glacier”.
line 174: Maybe a definite article is missing also here. I mean: “…of the procedure…”
line 189: “precipitated carbonate” Do you mean autochthonous carbonate?
line 276: “Significantly low values” sounds strange. Maybe simply “Lower values”
line 281: “decrease again up to” sounds strange. Maybe omit “up”
line 359: “The” instead of “the”
lines 371-377: I’m afraid that the proposed ideas cannot explain seasonal anoxic conditions.
line 391: “algaes” sounds like double-plural: I think “algae” is sufficient.
lines 427-430: I cannot see the rationale mentioning C4 plant here. C4 plants could become locally dominant only after maize cultivation spread in this region.
line 448: Add space between till and ca.
line 485: Ascunsa Cave is not in the northern Pannonian Basin.
line 488: Please correct the typo “Ernesto” instead of “Ernestoa”
line 494: I think a definite article is needed before the Carpathians. I mean: “…from the Carpathians…”
line 513: Please correct the typo in citation “Hercman” instead of “Hermcan”
line 514-519: Sorry, but the information provided here (referred to Russo et al., 2022, Park et al., 2019) is not at all linked to the paleoenvironmental changes deciphered from the analyzed record. What do you want to explain with the Arctic amplification, for instance?
Figures
Fig1: Please correct the typo in the map. “Western” instead of “Westhern”
Fig3: Arrows (both yellow and orange ones) should be increased.
Fig4: I cannot see the added value of the smoothing splines. The variance is so faint in the original values. In addition, a common axis label as “numValue” for all horizontal axes is unacceptable. Finally, the caption also needs some revision because LOI is not a chemical element.
Fig5 What is your goal with showing the general form of linear model in the plot? Anyway, is this plot needed at all? There is not any point in the discussion referring to this plot. My impression is that this figure is superfluous.
Fig8: What do you wish to present with this figure? In its current form this compilation of isotope records seems lacking a clear conception. Some annotation could help the reader to understand the climatic meaning of the different proxies (e.g. warm-cold, dry – wet). Some of the low-res records (e.g., Mituchovci, Poleva) hardly show any meaningful variance in this period. I’m afraid that these low-res records only confuse the readability rather than add to this picture. A final technical remark is that it is impossible to spell out the axis labels in the current layout
Citation: https://doi.org/10.5194/egusphere-2023-118-RC2
- AC2: 'Reply on RC2', Jan Petřík, 28 Apr 2023
  
  Dear reviewer,
  Thank you for taking the time to review our manuscript and providing valuable feedback. We are ready to implement most of the suggestions to improve the manuscript and make major revisions. At this point, I would like to address the main concerns and major points raised by the referee. The minor comments will be directly implemented into the next version of the manuscript.
  The isotopic analysis is based on the same carbonate precipitates throughout the section and should be independent of local paleobiological alteration. We argue that local environmental, lithological, and stable isotope record changes were caused by a supraregional climate shift. There is certainly proxy evidence of local change reflected by lithology, physicochemical proxies, and paleobiological proxies (c.f. Šolcová et al. 2018), which are taken into account and discussed. At the same time, this change is more likely associated with the local stable isotope record reflecting climate-hydrology changes, which are primarily influenced by the mean annual isotopic composition of meteoric water and the continentality effect in the case of δ18O and warmer periods (lower δ13C) or colder periods connected with reduced biological and pedological activity in soil (higher δ13C). We found the interpretation of increasing D13C during the detected shift in unit 4/3C (circa 7.3 ka BP) to be challenging, as it could indicate both warming and an increase in humidity. Other evidence (sedimentology, micromorphology) however, indicates drying and a consequent sedimentary hiatus (at least local drying). On the other hand, there is increasing D18O (warming) in the Santovka record and elsewhere. The detected shifts are certainly associated with changes in the local environment, but at the same time, we argue that changes in local conditions were caused by regional/supraregional climate shifts: "It could be partly caused by a change of water regime associated with the disappearance of Búr brook and/or waning of the mineral spring. This change is connected to environmental change recorded in an age-depth model about 7300 cal BP, more likely relating to a shift in climatic conditions".
  We appreciate your concerns regarding the occasional correspondence in D13C records and the potential lack of regionally coherent environmental change. We would like to clarify that the observed pattern in D13C is not a mere coincidence, but rather a repeating pattern in the records we have selected based on pre-defined criteria. Sites were selected according to time span, age, record resolution, geographic position, and data availability (for more details see lines 160-170). Our analysis focused on the recurring temporal pattern of D13C shifts, which we believe is indicative of a significant paleoclimatic phenomenon.
  Regarding the lack of a clear pattern in the δ18O shifts mentioned in line 329, we acknowledge that our initial statement might have caused confusion. We intend to revise this part of the manuscript to emphasize that, despite some inconsistencies, the recurring pattern in D13C records is of primary interest in our study.
  We have chosen the region of Central-Eastern and South-Eastern Europe to investigate changes in the influence of dominant air currents on paleoclimatic records. In order to study sub-millennial variations, we have selected relevant speleothem, lake sediment, travertine, and tufa isotopic records, as published paleobiological studies have few samples and thus insufficient resolution for the paleoclimatic record. That is why we have not used, for example, https://doi.org/10.1016/j.quascirev.2016.04.001.
  We also aimed to broaden the context of our research by correlating with hematite-stained grains in the North Atlantic Ocean (Bond et al., 2001), changes in Total Solar Irradiance (Steinhilber et al., 2009), which temporally fit with the detected climate shift. These proxies could be excluded if they are deemed a random collection of curves. Alternatively, we can further discuss the coincidence with the Sapropel S1 event and changes in salinity in the Marmara Sea and the Mediterranean around 7.5 ka BP (https://doi.org/10.1016/S0031-0182(02)00596-5).
  
  We will also supplement the methodological description of isotopic analysis. We could shorten the sedimentological and micromorphological description and move part of it to the supplementary material. The font type will be unified.
  Thank you once again for your valuable feedback, and we look forward to further improving our manuscript based on your suggestions.
  Sincerely, authors
  
  Citation: https://doi.org/10.5194/egusphere-2023-118-AC2
RC3:
'Comment on egusphere-2023-118', Anonymous Referee #3, 06 Apr 2023
This study reports data on a 2.8 m-high section of carbonate-bearing sediments that the authors describe as “travertine lake represented by lake marl deposits”.
I recommend this ms. to be rejected and submitted to a regional journal, or possibly a palaeolimnological or sedimentary journal, because its climate interpretation is not sufficiently well supported to justify publication in CP.
Here are some suggestions for improvement:
Provide a proper sediment log of this small outcrop, and put Table 1 into the supplement

I got confused about the type of carbonate-bearing sediments studied (travertine, carbonate concretions, marls..). Which type of carbonate is represented by the isotope data?

10 radiocarbon ages (incl. 1 obvious outlier) only provide a moderately well contrained depth-age model, which could/should be improved. E.g., the 8.2 event time window is poorly constrained and hinges on one (the basal) 14C age

Report age model uncertainties when referring to age data in the text

Provide calibrated 14C ages in Table 2

Not clear why the authors measured a number of elemental abundances (which are not really climate-sensitive) but did not include more sensitive proxies such as pollen or diatoms

The English needs some improvement, starting with the title
Citation: https://doi.org/10.5194/egusphere-2023-118-RC3
- AC3:
  'Reply on RC3', Jan Petřík, 15 May 2023
  Dear Reviewer,
  Thank you for your time and detailed feedback on our manuscript. We greatly value your comments and believe they will assist us in improving the quality of our work. Here, we address your specific points:
  
  Following your recommendation, we will revise the sediment log and move Table 1 to the supplementary section.
  
  We apologize for the confusion regarding the type of carbonate sediments studied. We have now improved the petrographic specification of the precipitated carbonates from which the isotope data are derived. We will ensure that this will be clearly articulated in the revised manuscript.
  
  We agree that our depth-age model can be enhanced. However, it should be noted that the model is based on 9 dates and is compiled in a standard manner. It is an improved and supplemented version of an age-depth model previously published. Specifically, the 8.2 event is located between dates UGAMS 10045 and UGAMS 10044 and there is minor deviation without inversion. Hence, we believe that the model is sufficient. Moreover, it is not a black box; we have made the entire code publicly available for reproducibility.
  
  We acknowledge that we should have reported age model uncertainties in the text. This will be rectified in the revised version.
  
  Thank you for pointing out the omission of calibrated radiocarbon data in Table 2. We will correct this oversight.
  
  Your query regarding the measurement of elemental abundances is justified. Paleoenvironmental analyses of pollen, plant macrofossils, and mollusks were conducted in a previous study. More sensitive proxies such as diatoms are a logical next step, and we are eager to perform their analysis in follow-up research.
  
  We apologize for the deficiencies in English. We will focus on language improvement, starting with the title.
  
  Finally, we appreciate your suggestion regarding publication in a regional or paleolimnological journal. However, we believe that our data and interpretations hold relevance for the broader climate science community and can contribute to a better understanding of past climate events. We will strive to make this clearer in the revised version of our manuscript. Moreover, our study has supra-regional significance as we document a climate shift that can be correlated within the Central and Southeastern European region, likely linked with global scale events.
  Thank you once again for your insightful feedback and guidance.
  Best regards,
  
  Jan Petrik
  
  Citation: https://doi.org/10.5194/egusphere-2023-118-AC3

Jan Petřík, Katarína Adameková, Sándor Kele, Rastislav Milovský, Libor Petr, Peter Tóth, and Nicholas McKay

Supplement

https://doi.org/10.5194/egusphere-2023-118-supplement

Data sets

Appendix Jan Petřík https://doi.org/10.5281/zenodo.7582204

Model code and software

Appendix Jan Petřík and Nichoals McKay https://doi.org/10.5281/zenodo.7582204

Jan Petřík, Katarína Adameková, Sándor Kele, Rastislav Milovský, Libor Petr, Peter Tóth, and Nicholas McKay

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Latest update: 17 Nov 2024

Short summary

Our analysis of the Santovka sedimentary record in Slovakia uncovered two major climate shifts at 8.2 and 7.4 ka BP. These shifts likely impacted temperature and humidity, and/or air mass circulation, and were caused by the drying of the lake at 7.4 ka BP. The sedimentary infill provides important information on the region's past climate, and future research must focus on its impact on the last hunter gatherers and first farmers in the context of spreading agriculture in Europe.


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