the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 30 Jul 2024
Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System
Abstract. Structural inheritance plays a significant role upon the evolution of fault systems in different tectonic settings. Both positive reactivation of pre-orogenic extensional faults and negative reactivation of syn-orogenic reverse faults during orogenic cycles have been extensively studied and documented. By contrast, only few studies have addressed the impact of structural inheritance in regions undergoing polyphase tectonic histories. Here, we present the Monti Martani Fault System (MMFS) case study (Northern Apennines, Italy) as an example of a seismically active region where it is possible to investigate the role of inherited pre-orogenic structural features upon the post-orogenic tectonic evolution. Based on new field structural data from extensional faults that controlled the Plio-Quaternary evolution of the system, we propose that the MMFS does not consist of a kilometer-long L-shaped single normal fault, as previously proposed in the literature, but is instead a set of several NW-SE trending shorter extensional faults arranged in an en-echelon style. Paleostress analysis yielded three distinct extension directions during the Plio-Quaternary post-orogenic extension, which are NE-SW, NNE-SSW and NW-SE. We relate the first two directions to local orientation fluctuations of the regional stress field interacting with moderately oblique inherited structural features, and the latter direction to a short-live orogen-parallel extensional event whose geodynamic causes remain unclear. We suggest that the NE-SW regional post-orogenic extension direction controls the strike of most of the NW-SE Apenninic-trending extensional faults, while the morphostructural trend of the Monti Martani Ridge and of its boundaries with the surrounding Plio-Quaternary Medio Tiberino and Terni basins is controlled by the strike of the ~N-S and ~E-W pre-orogenic (Jurassic) inherited structural features. We also discuss the implications of these observations upon the seismotectonics of the MMFS. Our findings suggest that, in contrast to previous suggestions, the fault system cannot be classified as an active and capable structural feature.
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Preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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RC1: 'Comment on egusphere-2024-2319', Marco Mercuri, 04 Sep 2024
Please find my comments in the attached pdf
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AC1: 'Reply on RC1', Riccardo Asti, 08 Oct 2024
Dear Dr. Marco Mercuri,
We wish to thank you for your thorough review and insightful comments on our manuscript entitled “Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System”. We sincerely appreciate the time and the effort that you spent to give a constructive contribution to our work. Your comments and suggestions have been thoroughly considered and integrated in the revised version of the manuscript. This surely helped us to improve the quality of the manuscript.
In the attached pdf file, we respond to each of your comments. We report your original comments in black, followed by the relative responses in red. We are confident that the suggested adjustments will strengthen the overall quality of the manuscript and we hope that our replies to your comments and the way we integrated them in the revised version of the manuscript will meet your satisfaction.
Yours sincerely,
Riccardo Asti
(on behalf of the co-authors)
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AC1: 'Reply on RC1', Riccardo Asti, 08 Oct 2024
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RC2: 'Comment on egusphere-2024-2319', Anonymous Referee #2, 18 Sep 2024
Revision of the paper “Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System” by Asti and coauthors
Dear Editors and Authors, I have carefully reviewed the manuscript by Asti et al. entitled “Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System”.
General Comments
In this study, the Authors present field data from structural stations to analyze the influence of pre-orogenic tectonic lineaments on the development of post-orogenic normal faults. The research was conducted in a distinctive area of the Central Apennines, specifically the Martani Mountains. This region, like the entire Umbria-Marche-Sabina Apennine, has undergone polyphase tectonic events recorded in the Meso-Cenozoic shallow-water to pelagic carbonates, Miocene syn-orogenic terrigenous units, and post-orogenic Plio-Quaternary marine-to-continental deposits. The study emphasizes the role of Tethyan rift inheritance, proposing that the present-day ridge geometry is controlled by these rift-related faults. According to the authors, these faults notably influenced the morphostructural configuration of the western and southern sectors of the Martani Mountains, resulting in an L-shaped ridge morphology. However, the authors did not perform detailed field mapping aimed at reconstructing the Jurassic paleotectonic setting or pre-orogenic tectonic architecture of the study area, instead inferring this from the existing literature.
The realization of structural stations at key outcrops and the subsequent analysis of the collected data led the authors to identify a set of several NW-SE trending extensional faults (defined “short”), arranged in an en-echelon pattern. These faults contrast with the N-S and WNW-ESE trending faults that bound the Martani Mountains to the west and south, which have been widely discussed in the literature. The field structural data were further analyzed to reconstruct the paleostress regime, revealing three distinct extension directions—NE-SW, NNE-SSW, and NW-SE—attributed to the Plio-Quaternary post-orogenic extension.
The identification of faults cutting through Pliocene and, in part, Pleistocene deposits, yet sealed by Upper Pleistocene deposits, allowed the authors to infer their potential seismotectonic significance.
In my opinion, the manuscript is written in clear and proficient English. The paper holds significant scientific potential and could be of interest to the Solid Earth audience. However, it has several weaknesses that should be addressed before it can be considered for publication. In particular, I recommend that the Authors:
- Provide clearer and more substantial field evidence to support their inferences regarding the existence of Plio-Quaternary faults intersecting and downthrowing high-displacement, pre-existing normal faults.
- Better define the pre-orogenic paleotectonic and stratigraphic framework of the study area, as well as the Plio-Pleistocene one.
- Strengthen the field constraints that underpin speculations about seismic hazard and paleostress analysis. This can only be achieved after establishing a relative chronology of the analyzed faults. As a result, intraformational faults should not be included in the analysis.
Specific comments are extensively discussed in the attached PDF, where editorial and typographic corrections are also noted. Additionally, several important citations of studies focused on the Martani Mountains are missing.
Specific comments
Early Jurassic paleotectonic-stratigraphic architecture of the Martani Mts.
The authors base their structural inferences on the influence of Early Jurassic rift faults in the development of pre-orogenic(?)/syn-orogenic(?)/post-orogenic(?) normal faults bounding the Martani Mountains Ridge (MMR), which result in its L-shaped morphology. However, the distinction between these stages is unclear in the text (see comments below). According to the Authors, the kilometers-long N-S and WNW-ESE trending fault(s) bounding the MMR to the west and south (i.e., Martana Fault Auctt) are Jurassic inheritances, as already stated by Bruni et al. (1995) and Cipriani et al. (2020). Nonetheless, the Authors do not provide their own field data to support this inference, which becomes evident from figures 3 and 4.
In fact, the geological map reported in Figure 3 is inadequate, as it is derived from a study that does not take the pre-Quaternary stratigraphy into account at all. By contrast, a study where structural inferences are drawn from inherited Jurassic paleotectonic and stratigraphic architecture requires a geological map that clearly delineates the pre-rift bedrock, the facies and thickness variations of syn and post-rift deposits, which are characteristic of the study region. Additionally, indirect evidence of rift faults - represented in the area by unconformity surfaces rather than shear zones (see Santantonio et al., 2017 for further details) - is missing, representing a major gap in the data. Comparable features are in Figure 4, where an oversimplified and obsolete litho-chronostratigraphic setting has been reported.
I suggest providing field evidence the pre-orogenic paleotectonic and stratigraphic framework of the study area, that could be identified not in limited structural stations, but after a widespread geological mapping involving the whole area.
Consequently, I invite to re-edit the geological map using the geological cartography of Regione Umbria at 1:10,000 scale, which should be updated with respect to the official geological map of Italy at 1:100,000 scale. Furthermore, I suggest to differentiate at least:
-the Calcare Massiccio, the latter being the pre-rifting substrate and providing information about the paleotectonic and stratigraphic setting;
- the Jurassic basinal succession, providing at least a unique color for the Corniola to Calcari Diasprigni formations;
- the Jurassic PCP-top condensed succession of the Bugarone group;
- the Maiolica to Bisciaro carbonate succession;
- the Schlier and Marnoso-Arenacea formations as siliciclastic succession.
Analogously, I strongly recommend replacing the chrono-lithostratigraphic scheme in Figure 4 with the updated version presented in Curzi et al. (2024), or at least drawing inspiration from it. The co-authors of the current work are also co-authors of the previously cited paper. Additionally, the colors used for the stratigraphic intervals should align with those specified earlier for the geological map.
Role of Jurassic rifting faults and present-day geometry
Assuming that the Martana Fault System is a Jurassic inheritance, and granting that I can also agree with what the Authors report, however, it is not clear in the text:
- if the fault system acted only in the pre-orogenic stage (i.e., since the Jurassic up to the Early Miocene);
- if if the fault system was reactivated in the Plio-Quaternary times, as stated for instance in the lines 430-435.;
- if the fault system was dissected by Plio-Quaternary NW-trending faults. In fact, the same Authors provide a structural dataset that is in contrast with what said above. According with them, the faults analysed in this manuscript are not coherent with the Plio-Quaternary regional stress direction and interacted with those inherited from the pre-orogenic phase. In the “Abstract” section the Authors write (Lines 12-15): “Based on new field structural data from extensional faults that controlled the Plio-Quaternary evolution of the system, we propose that the MMFS does not consist of a kilometer-long L-shaped single normal fault, as previously proposed in the literature, but is instead a set of several NW-SE trending shorter extensional faults arranged in an en-echelon style.” Analogously, in the lines 401-405: “…the morphostructural trend of the western and southern margins of the MMR does not correspond to continuous and several kilometer-long fault traces aligned along the ~N-S or WNW-ESE directions. Rather, the MMFS appears to be formed of several disconnected fault segments with different orientations, most of which are aligned with the main structural trend of the Plio-Quaternary extensional structures of the Northern and Central Apennines (i.e. NW-SE; e.g., Galadini & Galli 2000; Barchi, 2010).” This point is also addressed in the “Discussion” section and in the schematic reconstruction of the tectonic setting in Figure 16, where the analyzed faults are shown to dissect and displace the inherited faults, which are not reactivated contrarily to what stated in the text,.
This is quite confusing and the confusion about this topic is pervasive in the text, and in my opinion is related to the lack of field constraints that allow the Authors to infer if the NW-SE trending, en echelon normal faults they described played, or not, a crucial role in the structuration of the ridge.
One undeniable fact, in my opinion, is that the present-day morphostructural setting of the MMR is related to normal faults active at least in the Pliocene and the Early Pleistocene. The post-orogenic activity of these normal faults, which may have followed original structural elements inherited from pre-orogenic tectonic phases (if not clear, this is a point that I support in this work, as I am confident that these faults played a significant role during the pre-orogenic phase), cannot be ignored because:
- these faults must have accommodated huge displacements. Evidence for this comes from the Cenozoic lithostratigraphic units that characterize the hanging walls of the faults, as observed both in outcrop (and some of these have even been measured on the field - see Viepri outcrops) and, more notably, in the subsurface. In contrast, Jurassic deposits predominantly occur at the footwalls of the master faults along the western and southern margins of the MMR. Despite these large displacements may result from polyphase tectonic activity, the fact that these faults downthrow Cenozoic carbonates and syn-orogenic Miocene deposits onto Jurassic units – such as those exposed at Grutti, few hundred metres north of the Viepri structural section- indicates that the minimum age of faulting is post-orogenic. Perhaps Similar features might exist in the subsurface of the Medio Tiberino and Terni basins, if not for the overlying Plio-Pleistocene deposits—otherwise, we wouldn’t be debating this!
One suggestion: I invite you to take a look at the boreholes database (ex. Law 464/84 on the ISPRA website: https://sgi2.isprambiente.it/viewersgi2/). You could find useful informations;
- the faults analyzed in this work do not justify the large stratigraphic displacement reported above, especially because they are intraformational or with limited downthrowing (with the exception of Viepri fault);
- the MMR-bounding faults controlled the deposition of the Plio-Quaternary deposits of the Medio Tiberino and Terni basins, as documented by published works on the Plio-Pleistocene deposits of these sectors (see Conti & Girotti, 1977; Ambrosetti et al., 1987, Basilici 1997), and as reported by the Authors themself in the text.
Based on the above, some questions have arisen for me:
- If the activity of these faults was pre-orogenic, what produced the accomodation space for the accumulation of hundreds of metres (up to 2500 m) of marine-to-continental deposits during the Pliocene and Pleistocene?
- What produced the erosional surface on which the Plio-Quaternary marine-to-continental successions rest on?
- Why the N-S segment couldn't have acted as transfer fault of NW-SE o WNW-ESE faults, such those occurring North of Martano Mt and along the southern border of the MMR?
- Could the faults analysed in this work be the result of strain partitioning related to the activity of the faults bordering the MMR rather than faults related to a different genetic process (i.e., a different, Quaternary, stress field)? In fact, the whole analysed faults, except for the Sangemini structural stations, occur at the footwall of the master faults, that now are buried by Quaternary deposits beneath the Terni and Medio Tiberino basins, and whose kinematics are not clear.
These are issues that are not discussed in your paper and which, in my opinion, need to be addressed and discussed.
Role of post-rift and pre-orogenic tectonic phases in the Umbria-Marche Sabina area
The Apennines experienced polyphase tectonics, and this has impacted in the structural and stratigraphic evolution of this range. Under-estimation of post-Tethyan rift and pre-orogenic tectonic deformations could have repercussions on the structural analysis of selected areas. There is a growing literature considering synsedimentary extension-dominated tectonic phases affecting the Apennines in the post-rift to syn-orogenic time span (e.g., Bajocian, Barremian-Aptian, Cenomanian, Maastrichtian, Paleocene, Miocene - see, for istance, Centamore et al., 2007; Cipriani & Bottini, 2019a,b; Capotorti & Muraro, 2021, 2024; Sabbatino et al., 2021). The latter should have repercussions on the inferences discussed in this work, and cannot be underestimated.
I suggest to introduce at least in the "Geological setting" section, information about the occurrence of these tectonic phases.
Relationships between carbonate bedrock and Plio-Quaternary deposits
In the lines 405-408 is written: “... the contact between the Upper Pleistocene-Holocene deposits of the Medio Tiberino and Terni basins and the Meso-Cenozoic carbonate and siliciclastic rocks of the MMR is an unconformable stratigraphic contact and not an extensional tectonic contact as proposed by earlier studies (e.g., Ambrosetti et al., 1987; Bonini et al., 2003)."
Assuming that one does not exclude the other, I agree with the fact that at present the contact between the upper Quaternary deposits and the carbonate bedrock is of a stratigraphic and unconformable nature, but this cannot be the case for the Pliocene and Lower Pleistocene deposits (which are not exposed along the western edge of the MMR) and the Meso-Cenozoic rocks. That said, the present unconformity surface could be the legacy of the Late Pliocene and Early Pleistocene faulting whose fault scarps, similarly to what happened for the Early Jurassic faults, have been then shaped by morphogenetic agents and become the site of stratigraphic and no longer tectonic contacts. Comparable features have been documented in the close Narni-Amelia Ridge by Cipriani (2016, 2019); here, Pliocene faults are buried by, and fault scarps are onlapped by, marine to continental Plio-Quaternary deposits. Furthermore, the fault scarps are overprinted by bioerosions (lithophagous holes).
As a consequence, these stratigraphic relationships cannot permit to exclude a Plio-Pleistocene activity for the Martana Fault.
Another problem is the age provided for Plio-Quaternary deposits. I do not believe, in fact, that the purpose of this work was to provide, and therefore that you derived, the age of the deposits. In my opinion, it is necessary to quote the references the Authors used to provide the age of Plio-Quaternary deposits (see, for istance, Conti & Girotti, 1977, Ambrosetti et al., 1978, 1987; Basilici, 1997), introducing a sentence in the text where they explain why have been decided to rely on one author rather than another. This topic has inferences on the following points of discussion.
Structural stations and reconstruction of tectonic phases relationships
Punctual structural data cannot allow the Authors to confirm nor the reactivation in the post-orogenic phase of pre-orogenic structures, nor to limit their activity to the pre-orogenic stage, nor to discriminate if the studied faults dissect the inherited ones. Inferences about the relationships between tectonic elements can be made if the relative age of the activity of each fault is defined. Except for the structural stations of Viepri and Cesi, most of the analysed faults are intraformational and, even the identification of polyphase reactivations, a relative chronology for each phase of tectonic activity cannot be constrained. This is especially valid when analysing faults (and fractures) affecting the Calcare Massiccio. In fact, I want to emphasise the fact that the Calcare Massiccio has recorded all the various deformation phases (whether more or less important) that have involved today's north-central Apennines, from the Tethyan rifting to post-rift and pre-orogenic (Bajocian, Barremian-Aptian, Maastrichtian, Paleocene, Miocene) normal faulting, to synorogenic compression to post-orogenic extension. Taking into account this information, it would be important to recognise and provide a relative chronology of structures, that could be identified not in limited structural stations, but after a widespread geological mapping involving the whole area.
Seismic hazard
About the seismic hazard and the lenght of the faults analysed, in my opinion the data shown and discussed in this paper are not sufficient to assume that these faults are not seismogenic and that has no high potential magnitude. In order to infer the latter, you have to map the whole length of the faults and discriminate that those are limited segments (at the surface!). In fact, why they could not be linked at depth, producing tens of km-long faults? Palaeoseismologists could comment on the work by inviting you to do, for example, further investigations such as palaeoseismological trenches etc. This point needs of further field data.
Moreover, you have no geochronologic constraints for determining the age of dissected or sealing Quaternary deposits. Few thousand years can move the needle of the scale towards the capability of these lineaments to dissect the topographic surface.
Paleostress evolution
Another major weakness points of this work that should be addressed are represented by the reconstruction of the extensional tensors. In fact, the three identified orientations of σ3 (i.e, NE-SW, NNE-SSW and NW-SE) cannot be chronologically constrained, as yourself stated in lines 480-481. Despite that, you implicitly infer that the NW-SE oriented σ3 is post-orogenic. Based on what? Furthermore, why infer the existence of a further post-Pliocene but pre-Late Pleistocene NW-SE extensional deformative phase, for which there is no direct evidence (e.g. inherited faults displaced by younger NE-SW extensional faults)? Would it not be more parsimonious to link their presence to differential movements (i.e. strain partitioning) at the footwall of the faulted blocks, assuming the existence of buried master faults? Sorry but it is not clear to me.
Technical corrections
Abstract
This part should be rewritten accordingly to the comments provided in the Discussion section and in the present file.
Geological setting
Except for the "formazione marnoso-arenacea", all the lithostratigraphic units for the Umbria-Marche succession do not have the term "formation" in their name, and I suggest to delete "Fm." from each unit.
Line 79: Please do not use the term ‘series’, which is a formal chronostratigraphic unit, as a synonym for ‘succession’. I suggest replacing "series" with "succession" in the text.
Line 110: “Tertiary” is no more a chronostratigraphic unit, and should be changed with Cenozoic.
Lines 111-113 : I suggest to make reference to a wider literature (i.e., Calamita & Pierantoni, 1994, 1995; Alfonsi et al., 1991, 1995)
Line 117: Works that were focused on the Jurassic deposits are not quoted here. I suggest to introduce at least these references: Mariotti et al, 1979; Farinacci et al., 1981; Galluzzo & Santantonio, 2002
Line 120: The faults described by Bruni et al. are submarine fault palaeoscarpments. Before they were passively buried by the hangin wall basins filling successions and thus became an unconformity surface rather than a fault surface, these escarpments have undergone a complex evolution in their geomorphic evolution, which may have led them to assume geometries inconsistent with those of the rooted faults that generated them. Gravitational retreat is the main examples. For more details see Carminati & Santantonio, 2005 and Santantonio et al., 2017. As a consequence, I suggest caution in relying on this kind of data from a structural point of view.
Lines 148-149: “The Medio Tiberino Basin is a N-S to NNW-SSE trending graben to the west of the MMR and is filled by a ~500 m thick Upper Pliocene-Quaternary continental succession (Barchi et al., 1991; Basilici, 1997).” The thickness of these deposits reach up to 2300 m in the Collevalenza area (Ambrosetti et al., 1993 in Basilici, 1997).
In lines 160-170 the reference to Fig. 1b is erroneous, I suppose. Maybe you refer to Fig. 2 and Fig. 3.
Methods
Which kind of software have you used for the realization of stereographic projections? Please, provide a reference.
Discussion
Lines 425-428: I believe that in these reference lists (and in the geological setting section as well)important works focussed on the structural relationships of the Jurassic inheritances on the orogenic deformations, also involving the Martani Mts, are missing, as: Calamita & Pierantoni, 1994,1995; Scisciani, 2009, Scisciani et al., 2014; Curzi et al., 2024.
Conclusions
This part should be rewritten accordingly to the comments provided in the Discussion section and in the present file.
Figures
Figure 2: I suggest to update this figure introducing the main structural elements lacking in the present form, as drawned. I suggest to see the structural scheme by Calamita & Pierantoni (1995).
Figure 3: see previous comments. Furthermore, in the legend you talk about deposits. Consequently, chonostratigraphic rather than geochronologic units should be used.
Figure 4: see previous comments. Furthermore, Lias, Dogger and Malm are no more chronostratigraphic units, and should be avoided. Please, change with Lower, Middle and Upper.
Figure 7: Abbreviations in the triangular schemes should be provided in the caption.
Figure 11: Neptunian dike: as the name itself suggests, "neptunian" means that it was formed under water. Those in the figure are "clastic dikes", or "fissures filled with clastic, continental sediments".
Figure 12: in panels a and c the strike slip slickenlines are not so clear.
Figure 13: I'm not sure that what you indicate in this figure as "fractured bedrock" is really fractured bedrock. In fact, looking at the deposits it seems to be heterometric breccias, but above all chaotic (and not with a fitted fabric type structure that I would expect for a fractured substrate) with a finer reddened matrix. Are you sure that they are not continental deposits older than those indicated as "Upper Pleistocene slope debris"?
Figure 16: This figure is not correct. A W-dipping normal/trastensive fault displaced by SW-dipping extensional faults should have its trace dissected and shifted towards E in plant view, not towards W (see line drawing on the pdf).
Moreover, it is oversimplified. In fact, the southern boundary extension structure of the MMR is not oriented E-W, but WNW-ESE, and thus has an angle of about 20° of deviation from that of the regional sigma3.
Cited papers
Ambrosetti, P., Carboni, M. G., Conti, M. A., Costantini, A., Esu, D., Gandin, A., ... & Sandrelli, F. (1978). Evoluzione paleogeografica e tettonica dei bacini tosco-umbro-laziali nel Pliocene e nel Pleistocene inferiore. MEMORIE DELLA SOCIETA'GEOLOGICA ITALIANA, 19, 573-580.
Ambrosetti, P., Carboni, M. G., Conti, M. A., Esu, D., Girotti, O., La Monica, G. B., ... & Parisi, G. (1987). Il Pliocene ed il Pleistocene inferiore del bacino del Fiume Tevere nell’Umbria meridionale: The Pliocene and the Lower Pleistocene of the Tevere Basin in Southern Umbria. Geografia Fisica e Dinamica Quaternaria, 10(1), 10-33.
Basilici, G. (1997). Sedimentary facies in an extensional and deep-lacustrine depositional system: the Pliocene Tiberino Basin, Central Italy. Sedimentary Geology, 109(1-2), 73-94.
Calamita, F., & Pierantoni, P. P. (1995). Modalità della strutturazione neogenica nell'appennino umbro-sabino (italia centrale). STUDI GEOLOGICI CAMERTI. NUOVA SERIE, 1, 153-169.
Calamita, F. & Pierantoni, P. P. (1994). Structural setting of the southern Martani mountains (Umbrian Apennines: central Italy). MEMORIE DELLA SOCIETA' GEOLOGICA ITALIANA, 48(2), 549-557.
Calamita, F., & Pierantoni, P. P. (1995). Modalità della strutturazione neogenica nell'appennino umbro-sabino (italia centrale). STUDI GEOLOGICI CAMERTI. NUOVA SERIE, 1, 153-169.
Capotorti, F., & Muraro, C. (2021). Post-rift extensional tectonics at the edge of a carbonate platform: insights from the Middle Jurassic-Early Cretaceous Monte Giano stratigraphic record (central Apennines, Italy). Geologica acta, 19, 0012.
Capotorti, F., & Muraro, C. (2024). Jurassic to Quaternary reactivation of inherited structures in the central Apennines. Italian Journal of Geosciences, 143(1), 37-59.
Carminati, E., & Santantonio, M. (2005). Control of differential compaction on the geometry of sediments onlapping paleoescarpments: Insights from field geology (Central Apennines, Italy) and numerical modeling. Geology, 33(5), 353-356.
Centamore, E., Di Manna, P., & Rossi, D. (2007). Kinematic evolution of the Volsci Range: a new overview. BOLLETTINO-SOCIETA GEOLOGICA ITALIANA, 126(2), 159.
Cipriani, A. (2016). Geology of the Mt. Cosce sector (Narni Ridge, Central Apennines, Italy). Journal of Maps, 12(sup1), 328-340.
Cipriani, A. (2019). Geological map of the central part of Narni-Amelia Ridge (Central Apennines, Italy). Geological Field Trips & Maps, 11(2.2), 1-26.
Cipriani, A., & Bottini, C. (2019a). Early Cretaceous tectonic rejuvenation of an Early Jurassic margin in the Central Apennines: The “Mt. Cosce Breccia”. Sedimentary Geology, 387, 57-74.
Cipriani, A., & Bottini, C. (2019b). Unconformities, neptunian dykes and mass-transport deposits as an evidence for Early Cretaceous syn-sedimentary tectonics: New insights from the Central Apennines. Italian Journal of Geosciences, 138(3), 333-354.
Conti, M. A., & Girotti, O. (1978). Il Villafranchiano del" lago Tiberino", ramo Sud occidentale. Schema stratigrafico e tettonico. Geologica Romana, 16, 67-80.
Curzi, M., Cipriani, A., Aldega, L., Billi, A., Carminati, E., Van der Lelij, R., ... & Viola, G. (2024). Architecture and permeability structure of the Sibillini Mts. Thrust and influence upon recent, extension-related seismicity in the central Apennines (Italy) through fault-valve behavior. GSA Bulletin, 136(1-2), 3-26.
FARINACCI A., MALANTRUCCO G., MARIOTTI N. & NICOSIA U. (1981a) - Ammonitico Rosso facies in the framework of the Martani Mountains paleoenvironmental evolution during the Jurassic. In Farinacci A. & Elmi S. Eds., Rosso Ammonitico Symposium Proceedings, 311-334. Edizioni Tecnoscienza, Roma
Galluzzo, F., & Santantonio, M. (2002). The Sabina Plateau: a new element in the Mesozoic palaeogeography of Central Apennines. Bollettino della Società Geologica Italiana, 1, 561-588.
MARIOTTI N., NICOSIA U., PALLINI G. & SCHIAVINOTTO F. (1979) - Kimmeridgiano recifale presso Case Canepine (M. Martani,Umbria): ipotesi paleogeografiche. Geologica Romana, 18, 295- 315.
Scisciani, V. (2009). Styles of positive inversion tectonics in the Central Apennines and in the Adriatic foreland: Implications for the evolution of the Apennine chain (Italy). Journal of Structural Geology, 31(11), 1276-1294.
Scisciani, V., Agostini, S., Calamita, F., Pace, P., Cilli, A., Giori, I., & Paltrinieri, W. (2014). Positive inversion tectonics in foreland fold-and-thrust belts: A reappraisal of the Umbria–Marche Northern Apennines (Central Italy) by integrating geological and geophysical data. Tectonophysics, 637, 218-237.
Santantonio, M., Fabbi, S., & Bigi, S. (2017). Discussion on «Geological map of the partially dolomitized Jurassic succession exposed in the central sector of the Montagna dei Fiori Anticline, Central Apennines, Italy» by. Italian Journal of Geosciences, 136(2), 312-316.
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AC2: 'Reply on RC2', Riccardo Asti, 08 Oct 2024
Dear Reviewer,
We wish to thank you for your thorough review and insightful comments on our manuscript entitled “Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System”. We sincerely appreciate the time and the effort that you spent to give a constructive contribution to our work. Your comments and suggestions have been thoroughly considered and subsequently integrated in the revised version of the manuscript. This surely helped us to improve its quality.
In the attached pdf file, we respond to each of your comments. We report your original comments in black, followed by the relative responses in red. We also attach an annotated pdf where we respond to the specific comments and typographic/editorial suggestions. We are confident that the suggested adjustments will strengthen the overall quality of the manuscript. As you will notice in this rebuttal letter, we do not agree with all of your comments and we tried to clarify our position where our views differ from yours.
Yours sincerely,
Riccardo Asti
(on behalf of the co-authors) - AC3: 'Reply on RC2', Riccardo Asti, 08 Oct 2024
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2024-2319', Marco Mercuri, 04 Sep 2024
Please find my comments in the attached pdf
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AC1: 'Reply on RC1', Riccardo Asti, 08 Oct 2024
Dear Dr. Marco Mercuri,
We wish to thank you for your thorough review and insightful comments on our manuscript entitled “Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System”. We sincerely appreciate the time and the effort that you spent to give a constructive contribution to our work. Your comments and suggestions have been thoroughly considered and integrated in the revised version of the manuscript. This surely helped us to improve the quality of the manuscript.
In the attached pdf file, we respond to each of your comments. We report your original comments in black, followed by the relative responses in red. We are confident that the suggested adjustments will strengthen the overall quality of the manuscript and we hope that our replies to your comments and the way we integrated them in the revised version of the manuscript will meet your satisfaction.
Yours sincerely,
Riccardo Asti
(on behalf of the co-authors)
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AC1: 'Reply on RC1', Riccardo Asti, 08 Oct 2024
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RC2: 'Comment on egusphere-2024-2319', Anonymous Referee #2, 18 Sep 2024
Revision of the paper “Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System” by Asti and coauthors
Dear Editors and Authors, I have carefully reviewed the manuscript by Asti et al. entitled “Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System”.
General Comments
In this study, the Authors present field data from structural stations to analyze the influence of pre-orogenic tectonic lineaments on the development of post-orogenic normal faults. The research was conducted in a distinctive area of the Central Apennines, specifically the Martani Mountains. This region, like the entire Umbria-Marche-Sabina Apennine, has undergone polyphase tectonic events recorded in the Meso-Cenozoic shallow-water to pelagic carbonates, Miocene syn-orogenic terrigenous units, and post-orogenic Plio-Quaternary marine-to-continental deposits. The study emphasizes the role of Tethyan rift inheritance, proposing that the present-day ridge geometry is controlled by these rift-related faults. According to the authors, these faults notably influenced the morphostructural configuration of the western and southern sectors of the Martani Mountains, resulting in an L-shaped ridge morphology. However, the authors did not perform detailed field mapping aimed at reconstructing the Jurassic paleotectonic setting or pre-orogenic tectonic architecture of the study area, instead inferring this from the existing literature.
The realization of structural stations at key outcrops and the subsequent analysis of the collected data led the authors to identify a set of several NW-SE trending extensional faults (defined “short”), arranged in an en-echelon pattern. These faults contrast with the N-S and WNW-ESE trending faults that bound the Martani Mountains to the west and south, which have been widely discussed in the literature. The field structural data were further analyzed to reconstruct the paleostress regime, revealing three distinct extension directions—NE-SW, NNE-SSW, and NW-SE—attributed to the Plio-Quaternary post-orogenic extension.
The identification of faults cutting through Pliocene and, in part, Pleistocene deposits, yet sealed by Upper Pleistocene deposits, allowed the authors to infer their potential seismotectonic significance.
In my opinion, the manuscript is written in clear and proficient English. The paper holds significant scientific potential and could be of interest to the Solid Earth audience. However, it has several weaknesses that should be addressed before it can be considered for publication. In particular, I recommend that the Authors:
- Provide clearer and more substantial field evidence to support their inferences regarding the existence of Plio-Quaternary faults intersecting and downthrowing high-displacement, pre-existing normal faults.
- Better define the pre-orogenic paleotectonic and stratigraphic framework of the study area, as well as the Plio-Pleistocene one.
- Strengthen the field constraints that underpin speculations about seismic hazard and paleostress analysis. This can only be achieved after establishing a relative chronology of the analyzed faults. As a result, intraformational faults should not be included in the analysis.
Specific comments are extensively discussed in the attached PDF, where editorial and typographic corrections are also noted. Additionally, several important citations of studies focused on the Martani Mountains are missing.
Specific comments
Early Jurassic paleotectonic-stratigraphic architecture of the Martani Mts.
The authors base their structural inferences on the influence of Early Jurassic rift faults in the development of pre-orogenic(?)/syn-orogenic(?)/post-orogenic(?) normal faults bounding the Martani Mountains Ridge (MMR), which result in its L-shaped morphology. However, the distinction between these stages is unclear in the text (see comments below). According to the Authors, the kilometers-long N-S and WNW-ESE trending fault(s) bounding the MMR to the west and south (i.e., Martana Fault Auctt) are Jurassic inheritances, as already stated by Bruni et al. (1995) and Cipriani et al. (2020). Nonetheless, the Authors do not provide their own field data to support this inference, which becomes evident from figures 3 and 4.
In fact, the geological map reported in Figure 3 is inadequate, as it is derived from a study that does not take the pre-Quaternary stratigraphy into account at all. By contrast, a study where structural inferences are drawn from inherited Jurassic paleotectonic and stratigraphic architecture requires a geological map that clearly delineates the pre-rift bedrock, the facies and thickness variations of syn and post-rift deposits, which are characteristic of the study region. Additionally, indirect evidence of rift faults - represented in the area by unconformity surfaces rather than shear zones (see Santantonio et al., 2017 for further details) - is missing, representing a major gap in the data. Comparable features are in Figure 4, where an oversimplified and obsolete litho-chronostratigraphic setting has been reported.
I suggest providing field evidence the pre-orogenic paleotectonic and stratigraphic framework of the study area, that could be identified not in limited structural stations, but after a widespread geological mapping involving the whole area.
Consequently, I invite to re-edit the geological map using the geological cartography of Regione Umbria at 1:10,000 scale, which should be updated with respect to the official geological map of Italy at 1:100,000 scale. Furthermore, I suggest to differentiate at least:
-the Calcare Massiccio, the latter being the pre-rifting substrate and providing information about the paleotectonic and stratigraphic setting;
- the Jurassic basinal succession, providing at least a unique color for the Corniola to Calcari Diasprigni formations;
- the Jurassic PCP-top condensed succession of the Bugarone group;
- the Maiolica to Bisciaro carbonate succession;
- the Schlier and Marnoso-Arenacea formations as siliciclastic succession.
Analogously, I strongly recommend replacing the chrono-lithostratigraphic scheme in Figure 4 with the updated version presented in Curzi et al. (2024), or at least drawing inspiration from it. The co-authors of the current work are also co-authors of the previously cited paper. Additionally, the colors used for the stratigraphic intervals should align with those specified earlier for the geological map.
Role of Jurassic rifting faults and present-day geometry
Assuming that the Martana Fault System is a Jurassic inheritance, and granting that I can also agree with what the Authors report, however, it is not clear in the text:
- if the fault system acted only in the pre-orogenic stage (i.e., since the Jurassic up to the Early Miocene);
- if if the fault system was reactivated in the Plio-Quaternary times, as stated for instance in the lines 430-435.;
- if the fault system was dissected by Plio-Quaternary NW-trending faults. In fact, the same Authors provide a structural dataset that is in contrast with what said above. According with them, the faults analysed in this manuscript are not coherent with the Plio-Quaternary regional stress direction and interacted with those inherited from the pre-orogenic phase. In the “Abstract” section the Authors write (Lines 12-15): “Based on new field structural data from extensional faults that controlled the Plio-Quaternary evolution of the system, we propose that the MMFS does not consist of a kilometer-long L-shaped single normal fault, as previously proposed in the literature, but is instead a set of several NW-SE trending shorter extensional faults arranged in an en-echelon style.” Analogously, in the lines 401-405: “…the morphostructural trend of the western and southern margins of the MMR does not correspond to continuous and several kilometer-long fault traces aligned along the ~N-S or WNW-ESE directions. Rather, the MMFS appears to be formed of several disconnected fault segments with different orientations, most of which are aligned with the main structural trend of the Plio-Quaternary extensional structures of the Northern and Central Apennines (i.e. NW-SE; e.g., Galadini & Galli 2000; Barchi, 2010).” This point is also addressed in the “Discussion” section and in the schematic reconstruction of the tectonic setting in Figure 16, where the analyzed faults are shown to dissect and displace the inherited faults, which are not reactivated contrarily to what stated in the text,.
This is quite confusing and the confusion about this topic is pervasive in the text, and in my opinion is related to the lack of field constraints that allow the Authors to infer if the NW-SE trending, en echelon normal faults they described played, or not, a crucial role in the structuration of the ridge.
One undeniable fact, in my opinion, is that the present-day morphostructural setting of the MMR is related to normal faults active at least in the Pliocene and the Early Pleistocene. The post-orogenic activity of these normal faults, which may have followed original structural elements inherited from pre-orogenic tectonic phases (if not clear, this is a point that I support in this work, as I am confident that these faults played a significant role during the pre-orogenic phase), cannot be ignored because:
- these faults must have accommodated huge displacements. Evidence for this comes from the Cenozoic lithostratigraphic units that characterize the hanging walls of the faults, as observed both in outcrop (and some of these have even been measured on the field - see Viepri outcrops) and, more notably, in the subsurface. In contrast, Jurassic deposits predominantly occur at the footwalls of the master faults along the western and southern margins of the MMR. Despite these large displacements may result from polyphase tectonic activity, the fact that these faults downthrow Cenozoic carbonates and syn-orogenic Miocene deposits onto Jurassic units – such as those exposed at Grutti, few hundred metres north of the Viepri structural section- indicates that the minimum age of faulting is post-orogenic. Perhaps Similar features might exist in the subsurface of the Medio Tiberino and Terni basins, if not for the overlying Plio-Pleistocene deposits—otherwise, we wouldn’t be debating this!
One suggestion: I invite you to take a look at the boreholes database (ex. Law 464/84 on the ISPRA website: https://sgi2.isprambiente.it/viewersgi2/). You could find useful informations;
- the faults analyzed in this work do not justify the large stratigraphic displacement reported above, especially because they are intraformational or with limited downthrowing (with the exception of Viepri fault);
- the MMR-bounding faults controlled the deposition of the Plio-Quaternary deposits of the Medio Tiberino and Terni basins, as documented by published works on the Plio-Pleistocene deposits of these sectors (see Conti & Girotti, 1977; Ambrosetti et al., 1987, Basilici 1997), and as reported by the Authors themself in the text.
Based on the above, some questions have arisen for me:
- If the activity of these faults was pre-orogenic, what produced the accomodation space for the accumulation of hundreds of metres (up to 2500 m) of marine-to-continental deposits during the Pliocene and Pleistocene?
- What produced the erosional surface on which the Plio-Quaternary marine-to-continental successions rest on?
- Why the N-S segment couldn't have acted as transfer fault of NW-SE o WNW-ESE faults, such those occurring North of Martano Mt and along the southern border of the MMR?
- Could the faults analysed in this work be the result of strain partitioning related to the activity of the faults bordering the MMR rather than faults related to a different genetic process (i.e., a different, Quaternary, stress field)? In fact, the whole analysed faults, except for the Sangemini structural stations, occur at the footwall of the master faults, that now are buried by Quaternary deposits beneath the Terni and Medio Tiberino basins, and whose kinematics are not clear.
These are issues that are not discussed in your paper and which, in my opinion, need to be addressed and discussed.
Role of post-rift and pre-orogenic tectonic phases in the Umbria-Marche Sabina area
The Apennines experienced polyphase tectonics, and this has impacted in the structural and stratigraphic evolution of this range. Under-estimation of post-Tethyan rift and pre-orogenic tectonic deformations could have repercussions on the structural analysis of selected areas. There is a growing literature considering synsedimentary extension-dominated tectonic phases affecting the Apennines in the post-rift to syn-orogenic time span (e.g., Bajocian, Barremian-Aptian, Cenomanian, Maastrichtian, Paleocene, Miocene - see, for istance, Centamore et al., 2007; Cipriani & Bottini, 2019a,b; Capotorti & Muraro, 2021, 2024; Sabbatino et al., 2021). The latter should have repercussions on the inferences discussed in this work, and cannot be underestimated.
I suggest to introduce at least in the "Geological setting" section, information about the occurrence of these tectonic phases.
Relationships between carbonate bedrock and Plio-Quaternary deposits
In the lines 405-408 is written: “... the contact between the Upper Pleistocene-Holocene deposits of the Medio Tiberino and Terni basins and the Meso-Cenozoic carbonate and siliciclastic rocks of the MMR is an unconformable stratigraphic contact and not an extensional tectonic contact as proposed by earlier studies (e.g., Ambrosetti et al., 1987; Bonini et al., 2003)."
Assuming that one does not exclude the other, I agree with the fact that at present the contact between the upper Quaternary deposits and the carbonate bedrock is of a stratigraphic and unconformable nature, but this cannot be the case for the Pliocene and Lower Pleistocene deposits (which are not exposed along the western edge of the MMR) and the Meso-Cenozoic rocks. That said, the present unconformity surface could be the legacy of the Late Pliocene and Early Pleistocene faulting whose fault scarps, similarly to what happened for the Early Jurassic faults, have been then shaped by morphogenetic agents and become the site of stratigraphic and no longer tectonic contacts. Comparable features have been documented in the close Narni-Amelia Ridge by Cipriani (2016, 2019); here, Pliocene faults are buried by, and fault scarps are onlapped by, marine to continental Plio-Quaternary deposits. Furthermore, the fault scarps are overprinted by bioerosions (lithophagous holes).
As a consequence, these stratigraphic relationships cannot permit to exclude a Plio-Pleistocene activity for the Martana Fault.
Another problem is the age provided for Plio-Quaternary deposits. I do not believe, in fact, that the purpose of this work was to provide, and therefore that you derived, the age of the deposits. In my opinion, it is necessary to quote the references the Authors used to provide the age of Plio-Quaternary deposits (see, for istance, Conti & Girotti, 1977, Ambrosetti et al., 1978, 1987; Basilici, 1997), introducing a sentence in the text where they explain why have been decided to rely on one author rather than another. This topic has inferences on the following points of discussion.
Structural stations and reconstruction of tectonic phases relationships
Punctual structural data cannot allow the Authors to confirm nor the reactivation in the post-orogenic phase of pre-orogenic structures, nor to limit their activity to the pre-orogenic stage, nor to discriminate if the studied faults dissect the inherited ones. Inferences about the relationships between tectonic elements can be made if the relative age of the activity of each fault is defined. Except for the structural stations of Viepri and Cesi, most of the analysed faults are intraformational and, even the identification of polyphase reactivations, a relative chronology for each phase of tectonic activity cannot be constrained. This is especially valid when analysing faults (and fractures) affecting the Calcare Massiccio. In fact, I want to emphasise the fact that the Calcare Massiccio has recorded all the various deformation phases (whether more or less important) that have involved today's north-central Apennines, from the Tethyan rifting to post-rift and pre-orogenic (Bajocian, Barremian-Aptian, Maastrichtian, Paleocene, Miocene) normal faulting, to synorogenic compression to post-orogenic extension. Taking into account this information, it would be important to recognise and provide a relative chronology of structures, that could be identified not in limited structural stations, but after a widespread geological mapping involving the whole area.
Seismic hazard
About the seismic hazard and the lenght of the faults analysed, in my opinion the data shown and discussed in this paper are not sufficient to assume that these faults are not seismogenic and that has no high potential magnitude. In order to infer the latter, you have to map the whole length of the faults and discriminate that those are limited segments (at the surface!). In fact, why they could not be linked at depth, producing tens of km-long faults? Palaeoseismologists could comment on the work by inviting you to do, for example, further investigations such as palaeoseismological trenches etc. This point needs of further field data.
Moreover, you have no geochronologic constraints for determining the age of dissected or sealing Quaternary deposits. Few thousand years can move the needle of the scale towards the capability of these lineaments to dissect the topographic surface.
Paleostress evolution
Another major weakness points of this work that should be addressed are represented by the reconstruction of the extensional tensors. In fact, the three identified orientations of σ3 (i.e, NE-SW, NNE-SSW and NW-SE) cannot be chronologically constrained, as yourself stated in lines 480-481. Despite that, you implicitly infer that the NW-SE oriented σ3 is post-orogenic. Based on what? Furthermore, why infer the existence of a further post-Pliocene but pre-Late Pleistocene NW-SE extensional deformative phase, for which there is no direct evidence (e.g. inherited faults displaced by younger NE-SW extensional faults)? Would it not be more parsimonious to link their presence to differential movements (i.e. strain partitioning) at the footwall of the faulted blocks, assuming the existence of buried master faults? Sorry but it is not clear to me.
Technical corrections
Abstract
This part should be rewritten accordingly to the comments provided in the Discussion section and in the present file.
Geological setting
Except for the "formazione marnoso-arenacea", all the lithostratigraphic units for the Umbria-Marche succession do not have the term "formation" in their name, and I suggest to delete "Fm." from each unit.
Line 79: Please do not use the term ‘series’, which is a formal chronostratigraphic unit, as a synonym for ‘succession’. I suggest replacing "series" with "succession" in the text.
Line 110: “Tertiary” is no more a chronostratigraphic unit, and should be changed with Cenozoic.
Lines 111-113 : I suggest to make reference to a wider literature (i.e., Calamita & Pierantoni, 1994, 1995; Alfonsi et al., 1991, 1995)
Line 117: Works that were focused on the Jurassic deposits are not quoted here. I suggest to introduce at least these references: Mariotti et al, 1979; Farinacci et al., 1981; Galluzzo & Santantonio, 2002
Line 120: The faults described by Bruni et al. are submarine fault palaeoscarpments. Before they were passively buried by the hangin wall basins filling successions and thus became an unconformity surface rather than a fault surface, these escarpments have undergone a complex evolution in their geomorphic evolution, which may have led them to assume geometries inconsistent with those of the rooted faults that generated them. Gravitational retreat is the main examples. For more details see Carminati & Santantonio, 2005 and Santantonio et al., 2017. As a consequence, I suggest caution in relying on this kind of data from a structural point of view.
Lines 148-149: “The Medio Tiberino Basin is a N-S to NNW-SSE trending graben to the west of the MMR and is filled by a ~500 m thick Upper Pliocene-Quaternary continental succession (Barchi et al., 1991; Basilici, 1997).” The thickness of these deposits reach up to 2300 m in the Collevalenza area (Ambrosetti et al., 1993 in Basilici, 1997).
In lines 160-170 the reference to Fig. 1b is erroneous, I suppose. Maybe you refer to Fig. 2 and Fig. 3.
Methods
Which kind of software have you used for the realization of stereographic projections? Please, provide a reference.
Discussion
Lines 425-428: I believe that in these reference lists (and in the geological setting section as well)important works focussed on the structural relationships of the Jurassic inheritances on the orogenic deformations, also involving the Martani Mts, are missing, as: Calamita & Pierantoni, 1994,1995; Scisciani, 2009, Scisciani et al., 2014; Curzi et al., 2024.
Conclusions
This part should be rewritten accordingly to the comments provided in the Discussion section and in the present file.
Figures
Figure 2: I suggest to update this figure introducing the main structural elements lacking in the present form, as drawned. I suggest to see the structural scheme by Calamita & Pierantoni (1995).
Figure 3: see previous comments. Furthermore, in the legend you talk about deposits. Consequently, chonostratigraphic rather than geochronologic units should be used.
Figure 4: see previous comments. Furthermore, Lias, Dogger and Malm are no more chronostratigraphic units, and should be avoided. Please, change with Lower, Middle and Upper.
Figure 7: Abbreviations in the triangular schemes should be provided in the caption.
Figure 11: Neptunian dike: as the name itself suggests, "neptunian" means that it was formed under water. Those in the figure are "clastic dikes", or "fissures filled with clastic, continental sediments".
Figure 12: in panels a and c the strike slip slickenlines are not so clear.
Figure 13: I'm not sure that what you indicate in this figure as "fractured bedrock" is really fractured bedrock. In fact, looking at the deposits it seems to be heterometric breccias, but above all chaotic (and not with a fitted fabric type structure that I would expect for a fractured substrate) with a finer reddened matrix. Are you sure that they are not continental deposits older than those indicated as "Upper Pleistocene slope debris"?
Figure 16: This figure is not correct. A W-dipping normal/trastensive fault displaced by SW-dipping extensional faults should have its trace dissected and shifted towards E in plant view, not towards W (see line drawing on the pdf).
Moreover, it is oversimplified. In fact, the southern boundary extension structure of the MMR is not oriented E-W, but WNW-ESE, and thus has an angle of about 20° of deviation from that of the regional sigma3.
Cited papers
Ambrosetti, P., Carboni, M. G., Conti, M. A., Costantini, A., Esu, D., Gandin, A., ... & Sandrelli, F. (1978). Evoluzione paleogeografica e tettonica dei bacini tosco-umbro-laziali nel Pliocene e nel Pleistocene inferiore. MEMORIE DELLA SOCIETA'GEOLOGICA ITALIANA, 19, 573-580.
Ambrosetti, P., Carboni, M. G., Conti, M. A., Esu, D., Girotti, O., La Monica, G. B., ... & Parisi, G. (1987). Il Pliocene ed il Pleistocene inferiore del bacino del Fiume Tevere nell’Umbria meridionale: The Pliocene and the Lower Pleistocene of the Tevere Basin in Southern Umbria. Geografia Fisica e Dinamica Quaternaria, 10(1), 10-33.
Basilici, G. (1997). Sedimentary facies in an extensional and deep-lacustrine depositional system: the Pliocene Tiberino Basin, Central Italy. Sedimentary Geology, 109(1-2), 73-94.
Calamita, F., & Pierantoni, P. P. (1995). Modalità della strutturazione neogenica nell'appennino umbro-sabino (italia centrale). STUDI GEOLOGICI CAMERTI. NUOVA SERIE, 1, 153-169.
Calamita, F. & Pierantoni, P. P. (1994). Structural setting of the southern Martani mountains (Umbrian Apennines: central Italy). MEMORIE DELLA SOCIETA' GEOLOGICA ITALIANA, 48(2), 549-557.
Calamita, F., & Pierantoni, P. P. (1995). Modalità della strutturazione neogenica nell'appennino umbro-sabino (italia centrale). STUDI GEOLOGICI CAMERTI. NUOVA SERIE, 1, 153-169.
Capotorti, F., & Muraro, C. (2021). Post-rift extensional tectonics at the edge of a carbonate platform: insights from the Middle Jurassic-Early Cretaceous Monte Giano stratigraphic record (central Apennines, Italy). Geologica acta, 19, 0012.
Capotorti, F., & Muraro, C. (2024). Jurassic to Quaternary reactivation of inherited structures in the central Apennines. Italian Journal of Geosciences, 143(1), 37-59.
Carminati, E., & Santantonio, M. (2005). Control of differential compaction on the geometry of sediments onlapping paleoescarpments: Insights from field geology (Central Apennines, Italy) and numerical modeling. Geology, 33(5), 353-356.
Centamore, E., Di Manna, P., & Rossi, D. (2007). Kinematic evolution of the Volsci Range: a new overview. BOLLETTINO-SOCIETA GEOLOGICA ITALIANA, 126(2), 159.
Cipriani, A. (2016). Geology of the Mt. Cosce sector (Narni Ridge, Central Apennines, Italy). Journal of Maps, 12(sup1), 328-340.
Cipriani, A. (2019). Geological map of the central part of Narni-Amelia Ridge (Central Apennines, Italy). Geological Field Trips & Maps, 11(2.2), 1-26.
Cipriani, A., & Bottini, C. (2019a). Early Cretaceous tectonic rejuvenation of an Early Jurassic margin in the Central Apennines: The “Mt. Cosce Breccia”. Sedimentary Geology, 387, 57-74.
Cipriani, A., & Bottini, C. (2019b). Unconformities, neptunian dykes and mass-transport deposits as an evidence for Early Cretaceous syn-sedimentary tectonics: New insights from the Central Apennines. Italian Journal of Geosciences, 138(3), 333-354.
Conti, M. A., & Girotti, O. (1978). Il Villafranchiano del" lago Tiberino", ramo Sud occidentale. Schema stratigrafico e tettonico. Geologica Romana, 16, 67-80.
Curzi, M., Cipriani, A., Aldega, L., Billi, A., Carminati, E., Van der Lelij, R., ... & Viola, G. (2024). Architecture and permeability structure of the Sibillini Mts. Thrust and influence upon recent, extension-related seismicity in the central Apennines (Italy) through fault-valve behavior. GSA Bulletin, 136(1-2), 3-26.
FARINACCI A., MALANTRUCCO G., MARIOTTI N. & NICOSIA U. (1981a) - Ammonitico Rosso facies in the framework of the Martani Mountains paleoenvironmental evolution during the Jurassic. In Farinacci A. & Elmi S. Eds., Rosso Ammonitico Symposium Proceedings, 311-334. Edizioni Tecnoscienza, Roma
Galluzzo, F., & Santantonio, M. (2002). The Sabina Plateau: a new element in the Mesozoic palaeogeography of Central Apennines. Bollettino della Società Geologica Italiana, 1, 561-588.
MARIOTTI N., NICOSIA U., PALLINI G. & SCHIAVINOTTO F. (1979) - Kimmeridgiano recifale presso Case Canepine (M. Martani,Umbria): ipotesi paleogeografiche. Geologica Romana, 18, 295- 315.
Scisciani, V. (2009). Styles of positive inversion tectonics in the Central Apennines and in the Adriatic foreland: Implications for the evolution of the Apennine chain (Italy). Journal of Structural Geology, 31(11), 1276-1294.
Scisciani, V., Agostini, S., Calamita, F., Pace, P., Cilli, A., Giori, I., & Paltrinieri, W. (2014). Positive inversion tectonics in foreland fold-and-thrust belts: A reappraisal of the Umbria–Marche Northern Apennines (Central Italy) by integrating geological and geophysical data. Tectonophysics, 637, 218-237.
Santantonio, M., Fabbi, S., & Bigi, S. (2017). Discussion on «Geological map of the partially dolomitized Jurassic succession exposed in the central sector of the Montagna dei Fiori Anticline, Central Apennines, Italy» by. Italian Journal of Geosciences, 136(2), 312-316.
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AC2: 'Reply on RC2', Riccardo Asti, 08 Oct 2024
Dear Reviewer,
We wish to thank you for your thorough review and insightful comments on our manuscript entitled “Reconciling post-orogenic faulting, paleostress evolution and structural inheritance in the seismogenic Northern Apennines (Italy): Insights from the Monti Martani Fault System”. We sincerely appreciate the time and the effort that you spent to give a constructive contribution to our work. Your comments and suggestions have been thoroughly considered and subsequently integrated in the revised version of the manuscript. This surely helped us to improve its quality.
In the attached pdf file, we respond to each of your comments. We report your original comments in black, followed by the relative responses in red. We also attach an annotated pdf where we respond to the specific comments and typographic/editorial suggestions. We are confident that the suggested adjustments will strengthen the overall quality of the manuscript. As you will notice in this rebuttal letter, we do not agree with all of your comments and we tried to clarify our position where our views differ from yours.
Yours sincerely,
Riccardo Asti
(on behalf of the co-authors) - AC3: 'Reply on RC2', Riccardo Asti, 08 Oct 2024
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Selina Bonini
Giulio Viola
Gianluca Vignaroli
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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