Response to the comments made by Gabor Tari (reviewer 1)

Dear Gabor,

We highly appreciate all the comments you provided regarding our paper on inversion tectonics in NW Poland. Here is our response to your three general comments:

1. Indeed, one of the key points of our paper is description and analysis of thin-skinned inversion scenarios, without involvement of the crystalline basement. In order to better described and illustrate this, Fig. 1 was modified so it now also includes a model for master fault detached in evaporites as such scenario is reflected in our own data; additionally, relevant part of the text has been expanded.
2. Discussion on negative versus positive inversion has been expanded to better clarify our opinion that the term inversion should be rather restricted to the “classic” scenario proposed by Bally (and clearly described in your own paper from this volume). This is also in agreement with remarks made by Mark Cooper in his review of our paper. Additionally, we checked several textbooks and key papers (but not all, of course, so we might have missed something …) and haven’t found definition of “fault reactivation” suggesting that reactivation implies renewed activity in the same kinematic sense; we think that “reactivation” means just renewed activity, in the same or opposite kinematic sense: normal fault could be reactivated as normal or reverse / thrust fault, and vice versa, reverse / thrust fault could be reactivated as reverse / thrust or normal fault. Actually, very good illustration of reactivation of thrusts during normal faulting (i.e. in opposite kinematic sense) is shown in Fig. 2 in your very interesting recently published paper on the Miocene extension within the Alpine – Carpathian junction area (Tari et al. 2021, The connection between the Alps and the Carpathians beneath the Pannonian Basin: Selective reactivation of Alpine nappe contacts during Miocene extension. Global and Planetary Change, https://doi.org/10.1016/j.gloplacha.2020.103401).
3. We indeed just speculate about extensional reactivation of Caledonian thrusts being responsible for formation of half-grabens recently imaged by 3D seismics in NW Poland beneath the Zechstein evaporitic cover as much deeper high-quality seismic imaging, comparable to the results of e.g. PolandSPAN survey, would be required in order to map master faults at greater depths and to actually see their relationship to the Caledonian FTB. In the text we cited several papers that document late Paleozoic extensional reactivation of Caledonian thrusts and formation of extensional grabens (Braathen et al., 2002; Fossen, 2010; Koehl et al., 2018; Rowan and Jarvie, 2020; Séranne et al., 1989; Stemmerik, 2000). Additionally, Lassen et al. (2001), also cited in our paper, has an example from “our” part of Europe that is based on seismic data (although not of the highest quality). We think that these examples together with high-quality seismic image of the most frontal part of the Caledonian FTB provided by the regional high-end PolandSPAN survey that was used to construct our Fig. 9 provide enough basis for our speculations. Of course, other possibilities could not be definitely ruled out; hopefully in the future new deep seismic data would provide final answer to this problem.

You detailed comments in the annotated pdf file with our paper were mostly of technical character and have been considered while working on the revised version of our manuscript.

Here is our response to your suggestions regarding modifications of some of the figures:

Fig. 1: thick-skinned and thin-skinned descriptors added in the figure caption

Fig. 2: coastline added to the legend

Fig. 3: vertical scale annotated in TWT

Fig. 7: we tried to use different color displays for seismic data but end of the day we think that grey scale version provides best results, especially for panel C, so this figure hasn’t been modified.

Fig. 8: this figure was designed for one full page so removal of particular panels would not be in our opinion advisable; panel (k) was amended as suggested

Fig. 9: color of the basement was changes as suggested

Fig. 11: information about equal scales for both seismic examples was added to the text

Again, many thanks for your review. We hope to continue discussion on various aspects of inversion tectonics in the future.

Response to the comments made by Mark Cooper (reviewer 2).

Dear Mark,

A session held at the EGU General Assembly in 2019 and resultant Solid Earth Special Issue have been titled “Inversion tectonics – 30 years later” in order to emphasize 30 year anniversary of publication of the seminal GSL Special Publication No 44 “Inversion tectonics”, coedited by you and G.D. William. In this context, we are especially thankful for your very positive review of our paper on inversion tectonics in NW Poland.

All the linguistic corrections you suggested have been taken into account. Regarding specific comments you made in the annotated pdf file with our paper:

Line 65 and line 73: we are glad that you agree with us on our opinion regarding the term “negative inversion” etc. We expended a bit section with discussion of positive versus negative inversion in order to (a) better acknowledge discussion on the same topic contained in Cooper & Warren (2020), and (b) to better clarify our point of view and to accommodate concerns raised by Gabor Tari who was responsible for another review of our paper.

Line 112: Laurussia i.e. the supercontinent that was formed in late Silurian as a result of a closure of Iapetus Ocean and collision of Baltica, Avalonia and Laurentia and ceased to exist due to the Variscan orogeny in late Carboniferous is correct term here (c.f. https://www.intechopen.com/chapters/37859). Laurasia was formed in Carboniferous–Permian out of Siberia, Kazakhstan and Baltica.

Line 254: unfortunately, no deep wells have been drilled into the axial parts of the sub-Permian half grabens so no maturity data is available to provide additional constrains regarding amount of erosion and burial / uplift history.

Fig. 2 and Fig. 4: 355^O was changed to -5^O

Fig. 3: indeed, this is a subcrop map of the units beneath the Variscan unconfomity