Record of Mid-Eocene Warming Events in the Istrian Paleogene Basin, Neotethys (Outer Dinarides, Croatia)
, Đurđica Pezelj 2, Renata Lukić 2, Katja Mužek 1,2, Krešimir Petrinjak 1, Marija Horvat 1,* and Vlasta Ćosović 2Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn general:
The paper combines geochemical and micropaleontological approach to study evidence of Eocene thermal maxima in four short sections from Istria.
The materials and methods section would be much easier to read if it were structured in some way and divided into subsections.
I am uncomfortable with the manner in which definite ecological preferences are assigned to various nannofossil species. This should be done with caution and by including references and data that support the claims in each particular case.
The discussion should combine the findings from different aspects of this study more closely to produce a more robust joint interpretation.
Specific comments:
Line 21
The subdominance (the term should be defined – see comment to line 178) of C. pelagicus is interpreted as an indication of eutrophication from periodic upwelling. This approach is in agreement with the Cachao & Moita (2000 doi: 10.1016/S0377-8398(00)00018-9) paper, however, the situation appears to be more nuanced (e.g. Prista et al., 2023; https://doi.org/10.5194/cp-2023-31). The species is simultaneously still used as a cold-water species (e.g. Ballegeer et al., 2022, https://doi.org/10.1016/j.palaeo.2022.111184).
I realize this is not up for the authors of this paper to fix alone, but every time such a label is applied, the support (data and publication) for it should be explained in detail. Otherwise the assigned palaeoecological preferences can introduce confusion rather than order.
25, 540
- producta is interpretated as an indicator of warm-water and shallow mesotrophic environment with decreased species richness.
To some extent, the claim is supported with Wade & Bown, 2006, who name the same form R. antarctica and describe it as indicative of “normal salinity mesotrophic shallow water”.
Associations with species richness and fluctuating salinity depart from this source and have no clear support. Such interpretations should be explained and supported with references or data or abandoned.
53-54
Describing Zygrhablithus bijugatus as oligotrophic is problematic. Its ecological preferences are, for instance, discussed in Bindiu-Haitonic (2021, https://doi.org/10.1016/j.marmicro.2021.101988), where a much more complex picture is painted.
In another instance, the assemblages with Cy. floridanus, Reticulofenestra bisecta and Zygrhablithus bijugatus were described by Melinte M. (2005: Oligocene palaeoenvironmental changes in the Romanian Carpathians, revealed by calcareous nannofossils. Studia Geologica Polonica Kraków 124, 341–352) as indicative for warmer conditions with increased nutrients available.
Cherry picking attributes of “indicator” species is very problematic.
128
Isotope geochemistry is a branch of geochemistry, no need to list separately.
178
There is no universal definition of what dominance in the assemblage means. Selecting the criterion of reaching over 50 % of the assemblage is the most inclusive option. Interpreting criteria that can be defined in this manner must be approached with caution.
235-250
This part of the text is not part of the manuscript but originates from the from journal instructions for authors.
267
130 taxa in 12 samples with individual samples containing cca 35-55 species suggests very – if not extremely - high species richness. A word on the taxonomic approach and/or a full list of species in Supplementary material would help to understand this phenomenon.
274
Zygrablithus bijugatus reaching up to 22 % of the assemblage is truly remarkable. When explaining this, it is vital to adhere to well supported paleoecological interpretations or data and nort resort to simplified explanations such as .
280
... in 90 % of the samples. – with a total of 12 samples it would be better to provide the exact number.
298
Plate – including Nannotetrina would be nice – since it is a crucial taxon used for biostratigraphy.
367-368
GTS 2012 and 2020 used in same plot – why?
405
Title not appropriate, discussion on calcareous plankton only starts in line 425, before there is talk of benthic forams, isotopes and sediments.
415-416
Poorly phrased, please correct.
440
New paragraph would be appropriate when switching from forams to nanofossils.
440
Cy. floridanus is described as warm-water oligotrophic species. The species has frequently been described as eutrophic (e.g. Senemari & Jalili https://doi.org/10.1186/s42501-021-00092-2). The reference cited (71) indeed interprets the species as meso-oligotrophic on the basis of their data (nothing about warm water) but also provides a list of references, that argue otherwise.
If this species is considered oligotrophic, it should be explained why that is. On its own, the assumption is problematic and makes assigning ecological preferences to species seem arbitrary.
447-448
This palaeoecological claim in association to a species/form is well supported with research and a publication. Compare to others.
455-456
Directly associating high species richness with high productivity is problematic (see Wade et al., 1999 10.1146/annurev.ecolsys.30.1.257)
501-2
2 species dominate the assemblage with 43+16=59%
The definition of dominance is arbitrary, different authors use between 50 and 90 % of assemblage. This example of dominance is composed of a sum of the abundance of two species, one of which is assigned to a very precise paleoecological niche.
This is walking on a thin edge.
502
- producta in association with R. minuta is indicative of possibly shallow and stratified warm water environments with highly fluctuating salinity and nutrient levels during periods of runoff.
To some extent, the claim is supported with Wade & Bown, 2006, who name the same form R. antarctica and describe it as indicative of “normal salinity mesotrophic shallow water”.
Associations with water temperature have no clear support. Such interpretations should be explained and supported with references or data or abandoned.
522-523
- bisecta dominated the assemblage at 21 % - in contradiction with the definition of dominance used in this paper. Rephrase.
524
Very high species richness! I cannot say I ever encountered anything of the sort. It would be appropriate to present (e.g. include a full list of species determined into supplementary material for insight into taxonomical approach and identity of taxa determined to enable comparisons) and discuss this finding.
576
Please discuss evidence for stratification before including it here.
573, 589
Different triggering factors for thermal events first mentioned in conclusions. Please discuss first and attach to specific results.
Author Response
Record of mid-Eocene warming events in the Istrian Paleogene Basin, Neotethys (Outer Dinarides, Croatia)
by
Ines Galović, Đurđica Pezelj, Renata Lukić, Katja Mužek, Krešimir Petrinjak, Marija Horvat, and Vlasta Ćosović
Manuscript ID: Geosciences-3725186
Response to Reviewers – 2025, July 11
Dear Reviewer,
Please see the attachment.
With respect,
The authors
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsPlease look at the attached file.
Comments for author File: Comments.pdf
Author Response
Record of mid-Eocene warming events in the Istrian Paleogene Basin, Neotethys (Outer Dinarides, Croatia)
by
Ines Galović, Đurđica Pezelj, Renata Lukić, Katja Mužek, Krešimir Petrinjak, Marija Horvat, and Vlasta Ćosović
Manuscript ID: Geosciences-3725186
Response to Reviewers – 2025, July 11
Dear Reviewer,
Please see the attachment.
With respect,
The authors
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript deals with the analysis of flysch deposits, which in general are affected by reworking processes. However, the authors have managed to provide reasonable results.
Some points need to be addressed.
Introduction: Most of the text in lines 43-94 should be moved into discussion
Material & Methods: L. 215, in supplements S1 and S2 there no information concerning the ecology of planktonic foraminifera
Material & Methods: Lines 235-246 must be deleted
Results: Lines 248-250 must be deleted
Figures: A figure presenting the planktonic foraminifera results and the biostratigraphic events and biozones is needed (similar to Figure 2)
Discussion: the very few (7) bulk sediment samples analysed for isotopes are not providing really convincing data...The outcrops are very short and the available samples few. Actually Fig. 4 shows the big difference in data resolution between the so far studied ODP sites and geological sections in respect to the data of the present study. Thus, it seems that the paleoclimatic evidence of the present study and the plankton response are somehow rather overinterpreted.
The geochemical data are practically not discussed.
L. 421. such data are not presented..
Comments on the Quality of English LanguageEnglish language needs to be further polished
Author Response
Record of mid-Eocene warming events in the Istrian Paleogene Basin, Neotethys (Outer Dinarides, Croatia)
by
Ines Galović, Đurđica Pezelj, Renata Lukić, Katja Mužek, Krešimir Petrinjak, Marija Horvat, and Vlasta Ćosović
Manuscript ID: Geosciences-3725186
Response to Reviewers – 2025, July 11
Dear Reviewer,
Please see the attachment.
With respect,
The authors
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsI am disappointed to find that a large majority of issues raised in my initial review remains unanswered.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript has been improved and the authors have replied sufficiently to all my comments. I believe the manuscript can be now accepted for publication
