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Dear Editor,

the paper " Post-Caledonian tectonic evolution of the Precambrian and Palaeozoic Platforms boundary zone offshore Poland based on the new and vintage multi-channel reflection seismic data" by Nguyen et al. is essentially divided into two parts. The first part of the work introduces the application of a workflow for eliminating multiple reflections, guided waves, and seismic interference from a dataset acquired in a shallow water depth environment. Additionally, the re-processing of some high-resolution legacy profiles in the Baltic Sea is also presented. The second part of the work focuses on the interpretation of seismic profiles from three different datasets. The aim is to demonstrate the tectonic evolution of the Koszalin Fault and its relationship with the Caledonian Deformation Front (CDF). Furthermore, a conceptual model is developed to illustrate the tectonic evolution of the transition zone between the Precambrian and Paleozoic Platforms offshore Poland.

The work presented in the manuscript is certainly of interest for publication in Solid Earth, especially considering the excellent quality of the seismic data presented. However, I recommend that the paper undergoes major revisions before it can be considered for publication.

Main comments

• The first part of the work describes the application of a specific workflow to the BalTec data acquired in 2016, but it does not provide new information on the processing compared to the report published in 2020 (Nguyen Q, 2020, Seismic Data Processing Report (BALTEC / MSM52). Institute of Geophysics PAS. https://dspace.igf.edu.pl/xmlui/handle/123456789/112). Perhaps the authors could add more details about the processing in this work. For instance, velocity models used for pre-stack migration are not displayed, and it would be helpful to show them alongside the seismic sections. In the description of the re-processing of PG197 profiles, the authors explain the need for a new velocity analysis compared to the original processing and that this new velocity analysis is picked on cleaner CDPs gathers (L251-252); I suggest showing an example of CDPs gather with its corresponding velocity analysis. The authors could also add these figures in a supplementary material.

• I would suggest a reorganization of some sections of the paper:

In my opinion, a "results" paragraph is missing, where the outcomes of the processing are illustrated, including a description of seismic sections in terms of reflectivity and characteristics of the reflectors (e.g., amplitudes, frequencies, geometries, continuity, etc.). Additionally, in this paragraph, it would be useful to discuss an estimate of the difference in vertical resolution between the BalTec and PG197 data.

There are several repetitions between paragraphs 4.1 and 6.1; please check.

The "discussion" paragraph could incorporate the geological interpretation of the seismic sections, by merging the content of the current paragraphs 5 and 6.3.

• The authors point out that data interpretation poses a challenge due to the limited well control in the area (L265). In their interpretation, they rely on well L2/1-87 situated at the southwest edge of profile BGR16-258. The horizon interpretation is then expanded from other wells using cross-sections, which are not shown in the manuscript. To enhance their approach, the authors might consider utilizing the boreholes intersected by the other BalTec lines to establish a correlation between stratigraphic markers and seismic facies. Subsequently, they could use the seismic facies to extend the interpretation. This “seismic facies table”, together with the description of the seismic facies could represent the new paragraph 5 “seismic interpretation”.

• I would like to preface by stating that seismic interpretation is not my primary expertise, and I hope that other reviewers can provide insights on this matter. I found the interpretation of the seismic sections to be insufficiently detailed, often overlooking clear structures and containing some errors. I recommend that the authors revisit the interpretation, aiming to better follow the main reflectors indicated by the seismic imaging and interpreting details that, in my opinion, could support the tectonic conceptual model. Furthermore, I recommend enhancing the line drawing by following the geometries of the reflectors. I have highlighted some examples in the attached PDF.

• The authors have reprocessed the PG197-13 and PG197-202 profiles, demonstrating the enhancement between the original processing flow and the reprocessing flow in Figure 7. I agree with the improvement in data quality. However, the interpretation of these reprocessed profiles is less detailed compared to the interpretation of the original profiles proposed by Krzywiec et al. 2003. Improving vintage data should aim to achieve a more detailed interpretation of the data. Therefore, I suggest that the authors also reconsider the interpretation of the reprocessed PG197 profiles.

Specific comments and minor suggestions are provided in the attached PDF file.