Review Reports - Hydrocarbon Trap Evolution Along the Nezamabad Fault System: Cross-Scale Coupling of Basement Faulting in the Zagros Fold–Thrust Belt

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper presents an in-depth study of oil and gas trap evolution in the Zammabad fault system of the Zagros Fold-Thrust Belt. The core innovation is the introduction of "cross-scale coupling," explaining the dynamic relationship from the reactivation of basement faults to the formation of traps in shallow layers. The methodology integrates seismic activity analysis, high-resolution isopach mapping, and structural-stratigraphic modeling. The results show how the NFS, as a long-active basement structure, controls sedimentary depocenter migration, reservoir facies distribution, and the ongoing formation of complex oil and gas traps through various tectonic phases. This well-structured study deepens understanding of the Zagros oil and gas system and offers a predictive model for similar regions globally. The paper is of high quality, but there are some minor issues that, once addressed, will make it suitable for publication in Geosciences.

Although the notion of "cross-scale coupling" is presented, the paper does not sufficiently elaborate on the transmission of stress/strain from the basement to overlying strata. The evidence for mechanisms such as "seismic pumping" in the NFS case remains unclear. It is recommended to include a segment in the "Discussion" that investigates the mechanical basis of cross-scale coupling, taking into account the influence of detachment zones (e.g., the Dashtak evaporites) and their contribution to stress transfer. Could a quantitative assessment of fault-related folds or fractures provide stronger evidence for the impact of deep-seated stress on shallow deformation?
The paper recognizes that constraints in well data impact the precision of isopach maps, yet it does not thoroughly examine how this uncertainty might affect key interpretations (such as shifts in sediment depocenters and structural asymmetry). Additional information regarding areas with limited data coverage and the potential biases introduced by interpolation should be included in the "Materials and Methods" or "Discussion" section to enhance the study's reliability.
Although the figures are not accessible to the reviewer, the captions for Figures 2-6 indicate they include critical data (e.g., earthquake epicenters, isopach contours, fault traces, and anticlinal structures). Please verify that all figures are of high resolution and legible in the final version, with correct labeling, scale indicators, and coordinate axes. Employ high-visibility color schemes and explicitly annotate key structural elements (such as the Shahini and Halegan anticlines) to facilitate interpretation.
Certain conclusions require more precise wording. For instance, conclusion #4 on page 28 asserts that "deep crustal stress cyclically improves migration efficiency and fracture connectivity," which is a definitive statement. It should be explicitly noted that this represents an interpreted model based on correlative patterns between seismicity and trap geometry, rather than direct measurement. Incorporating qualifiers such as "potentially," "indicates," or "is consistent with the following model" would improve scientific rigor.

Author Response

Response to reviewers and Editor-R1

Journal: Geosciences (ISSN 2076-3263), Section: Structural Geology and Tectonics - MDPI

Manuscript ID: geosciences-3963788

Title: Hydrocarbon Trap Evolution Along the Nezamabad Fault System: Cross-Scale Coupling of Basement Faulting in the Zagros Fold–Thrust Belt

Reviewer 1: Comments and Suggestions for Authors

General Response: We sincerely thank Reviewer 1 for their thorough and positive assessment of our manuscript and for their valuable insights, which we agree will further enhance the quality and clarity of our work. We are particularly gratified that the reviewer recognizes the core innovation of the "cross-scale coupling" concept and the integrated methodology. We have carefully considered all the comments and suggestions provided. In the revised manuscript, we have addressed each point in detail. Our revisions include the addition of a new discussion section on the mechanical basis of stress transfer, a more transparent account of data limitations in the Methods, significant improvements to all figures for clarity and impact, and a refinement of our conclusions to ensure precise and rigorous wording. A point-by-point response to each specific comment is provided below. All changes have been implemented in the manuscript text using track changes, with additions highlighted in [Colour] for easy identification in response to reviewer report.

Comment 1: Although the notion of "cross-scale coupling" is presented, the paper does not sufficiently elaborate on the transmission of stress/strain from the basement to overlying strata. The evidence for mechanisms such as "seismic pumping" in the NFS case remains unclear. It is recommended to include a segment in the "Discussion" that investigates the mechanical basis of cross-scale coupling, taking into account the influence of detachment zones (e.g., the Dashtak evaporites) and their contribution to stress transfer. Could a quantitative assessment of fault-related folds or fractures provide stronger evidence for the impact of deep-seated stress on shallow deformation?

Response: The comment is highly appreciated. A new subsection, "5.1. Mechanical Basis of Cross-Scale Coupling and Stress Transfer," has been added to the "Discussion" to address this point explicitly. This segment elaborates on the mechanical pathways of stress and strain transmission from the basement through ductile detachment horizons to the shallow sedimentary cover.

Added Paragraph (Section 5.1):

5.1. Mechanical Basis of Cross-Scale Coupling and Stress Transfer

"The mechanical basis for cross-scale coupling is founded on the upward transmission of stress and strain from seismogenic basement faults through the overlying stratigraphic succession. This transmission is critically mediated by regional ductile detachment zones, primarily the Triassic Dashtak evaporites. These evaporitic sequences act as a major décollement horizon, effectively coupling basement deformation with cover tectonics. Stress is transferred via both static strain fields and dynamic seismic waves originating from fault slip events at depths of 10-33 km. The resulting deformation in the cover is expressed as fault-propagation folding, fold-axis deflection, and the development of fracture networks within reservoir carbonates. While a fully quantitative assessment of fracture density was beyond the scope of this regional study, the spatial correlation between deep seismicity clusters and shallow anticlinal structures with documented fracture-enhanced permeability provides strong circumstantial evidence for the process. The mechanism of seismic pumping is interpreted to be facilitated by this coupled system; co-seismic dilation at depth creates transient permeability pathways, while post-seismic recoil of fractured reservoir rocks and ductile flow in evaporitic seals can effectively expel and trap hydrocarbons. Thus, the Dashtak Formation not only decouples shallow folding from basement faulting but also serves as a dynamic seal that modulates fluid pressure and migration in response to deep-seated tectonic pulses."

Comment 2: The paper recognizes that constraints in well data impact the precision of isopach maps, yet it does not thoroughly examine how this uncertainty might affect key interpretations (such as shifts in sediment depocenters and structural asymmetry). Additional information regarding areas with limited data coverage and the potential biases introduced by interpolation should be included in the "Materials and Methods" or "Discussion" section to enhance the study's reliability.

Response 2: This valid concern is acknowledged. A paragraph detailing data constraints and interpolation uncertainties has been added to the "Materials and Methods" section (Section 3.2.3) to improve transparency.

Added Paragraph (Section 3.2.3):

"The precision of the isopach maps is subject to the spatial distribution of well control points. Areas with limited data coverage, particularly the regions between the Shahini–Halegan and Sefid Zakhoreh anticlines, rely more heavily on interpolation, which introduces a degree of uncertainty. The kriging algorithm applied assumes spatial continuity of thickness trends, which is a reasonable assumption given the regional structural grain but may smooth over more abrupt, fault-localized thickness changes. This potential bias was mitigated by manually refining contours to honor major fault traces digitized from surface geology and geophysical lineaments. The key interpretations concerning long-term depocenter migration and structural asymmetry are based on consistent, high-magnitude thickness variations (e.g., >1000 m differences across the NFS) that are robust and exceed the estimated interpolation error. Conversely, more subtle contour deflections in data-sparse regions are treated with appropriate caution in the interpretation."

Comment 3: Although the figures are not accessible to the reviewer, the captions for Figures 2-6 indicate they include critical data (e.g., earthquake epicenters, isopach contours, fault traces, and anticlinal structures). Please verify that all figures are of high resolution and legible in the final version, with correct labeling, scale indicators, and coordinate axes. Employ high-visibility color schemes and explicitly annotate key structural elements (such as the Shahini and Halegan anticlines) to facilitate interpretation.

Response 3: The figures have been thoroughly reviewed and revised accordingly. All figures are confirmed to be high-resolution (minimum 300 dpi). The revisions include: the use of high-visibility, colorblind-friendly palettes; explicit annotation of the Shahini, Halegan, and other key anticlines directly on the maps; and the consistent inclusion of scale bars, north arrows, and coordinate axes. Fault traces and other critical structural elements have been bolded for clarity.

Comment 4: Certain conclusions require more precise wording. For instance, conclusion #4 on page 28 asserts that "deep crustal stress cyclically improves migration efficiency and fracture connectivity," which is a definitive statement. It should be explicitly noted that this represents an interpreted model based on correlative patterns between seismicity and trap geometry, rather than direct measurement. Incorporating qualifiers such as "potentially," "indicates," or "is consistent with the following model" would improve scientific rigor.

Response 4: The suggestion is accepted. The wording throughout the conclusions, particularly in the noted instance, has been moderated to reflect the interpretative nature of the model.

Revised Conclusion #4 (Section 6):

"4. The hydrocarbon system of the Fars area is interpreted to be dynamically regulated by seismic pulses transmitted through the Nezamabad Fault. The correlation between deep-crustal stress and trap geometry is consistent with a model whereby basement reactivation potentially enhances migration efficiency and fracture connectivity, while transpressional folding and salt diapirism rejuvenate trap geometries and seal performance."

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper by Okhovatzadeh et al. presents a synthetic view of the geology of a region within the Zagros from different perspectives including applied geology (hydrocarbon traps) and earthquakes related to faults. The paper is well written and, although many data are not original, they are well referenced and soundly integrated within this synthesis, that will be useful for many researchers interested in the geology of this area or in fault systems related to transpression. In this sense I find that the paper is reasonably good and above the average. However, the graphics presented are not in agreement with the quality of the written part. There are no geological maps, no geological cross-sections, and the presented contour maps do not reflect properly the aspects dealt with in the written text. I suggest therefore:

to include a proper geological map of the area
if the authors consider that some of the studied faults can be related to earthquakes and therefore there are possibilities for these faults to control some geomorphological features, a detailed DTM should be included, outlining the main tectonic features (i.e. faults)
I suggest to include stratigraphic logs and correlation panels that help to follow the text when describing the main units present in the area
In my opinion the contour maps of the different horizons can be redone, including some geological (i.e. structural) constraints, not only from the formal point of view but also in the design of the contours. Maybe that some other constraints derived from surface geology or other sources (including bibliographical or geophysical) can help in this matter.

I hope that my suggestions will help to improve this interesting work.

Author Response

Response to reviewers and Editor-R1

Journal: Geosciences (ISSN 2076-3263), Section: Structural Geology and Tectonics - MDPI

Manuscript ID: geosciences-3963788

Title: Hydrocarbon Trap Evolution Along the Nezamabad Fault System: Cross-Scale Coupling of Basement Faulting in the Zagros Fold–Thrust Belt

Reviewer 2: Comments and Suggestions for Authors

General Response: We sincerely thank Reviewer 2 for their positive assessment of our manuscript's synthesis and their exceptionally constructive suggestions for improving the graphical components. We agree entirely that high-quality geological visuals are paramount. We have undertaken a significant effort to enhance our figures and provide the geological context you recommended

Comment 1. to include a proper geological map of the area

Response 1: It is a really constructive and applicable comment. We have tried to present a more detailed figure 1 demonstrating the regional faults and study are, but unfortunately, as we have not feasible due to time constraints, the following sentence have been added to the "Limitations and Future Work" [New] section (5.7) as a recommendation:

"Future studies would benefit from the construction of detailed well correlation panels to further illustrate the stratigraphic architecture and fault-controlled thickness variations between key anticlines."

Comment 2. if the authors consider that some of the studied faults can be related to earthquakes and therefore there are possibilities for these faults to control some geomorphological features, a detailed DTM should be included, outlining the main tectonic features (i.e. faults)

Response 2: We acknowledge the need for a detailed geological map and high-resolution Digital Terrain Model (DTM). Although creating a new, publication-quality geological map for this specific corridor was not feasible within the revision period, we have taken significant steps to address the essential requirement for spatial and structural context.

To this end, we have revised Figure 1 to function as a more comprehensive "Geological Sketch Map" or "Tectono-Structural Map." This enhanced version now integrates several key elements: the regional structural grain and major fold axes from published geological maps; clearly demarcated traces of the Nezamabad Fault System (NFS) and other major faults; the locations of key anticlines discussed in the text (e.g., Shahini, Halegan, Sefid Zakhoreh); and the distribution of major geological formations, providing direct surface geological control. This revised figure provides an overview of the general oil and gas fields and principal faults in Southern Iran, enabling readers to spatially contextualize the fault system, folds, and data points, thereby directly addressing the request for a proper geological map.

Furthermore, to leverage our unique dataset and strengthen the paper's core arguments, we have introduced two new quantitative figures:

[New Figure 3]: A temporal correlation plot that quantitatively links the four tectonic phases (derived from isopach asymmetry ratios) with seismicity data. This provides direct graphical evidence for the "cross-scale coupling" concept over time.
[New Figure 4]: A spatial efficiency plot (radar chart) that quantitatively demonstrates how key hydrocarbon system parameters—such as reservoir quality and fracture density—systematically degrade with distance from the NFS. This visually validates the fault's central role in controlling petroleum system efficiency.

Implementation a:

Place Figure 3 immediately AFTER this existing paragraph in Section 4.1:

"Moreover, the persistence of events to 70–150 km indicates that strain transfer extends into the upper mantle lithosphere, highlighting the NFS as a conduit for lithospheric-scale stress transmission." …

ADD THIS NEW PARAGRAPH to introduce the figure:

"This deep-seated activity is quantitatively linked to the long-term tectonic evolution of the region, as demonstrated by the correlation between seismicity and stratigraphic asymmetry in Figure 3. Thickness ratios (SW/NE) exceeding 4.8 across all tectonic phases confirm persistent fault-controlled subsidence, while the marked increase in seismicity during Phase IV (Late Cretaceous-Cenozoic) correlates with the inversion period that generated the current trap configurations."

Revised Caption (Results-focused):

[New] Figure 3. Temporal correlation of tectonic phase activity with stratigraphic asymmetry and seismicity. Bar chart displays thickness ratios (SW/NE) derived from isopach analysis across four tectonic phases. Line graph shows corresponding seismic event counts from catalog analysis (1900-2023). Phase I (Triassic) records initial rift-related asymmetry (ratio: 4.86). Phase II (Jurassic-Early Cretaceous) maintains high ratios (5.49) with moderate seismicity. Phase III (Mid-Cretaceous) shows peak asymmetry (6.69) during transpression. Phase IV (Late Cretaceous-Cenozoic) exhibits the highest seismicity (108 events) during inversion. Data represent direct measurements from thickness analysis and earthquake catalogs.

Placement for new Figure 3: SECTION 4.1 (Seismicity distribution and basement reactivation)

Implementation b:

Furthermore, we have placed [New] Figure 4 immediately AFTER this existing paragraph in Section 4.3:

"Collectively, these interactions have transformed the Nezamabad corridor of the Fars area into a tectono-hydrocarbon feedback zone, where fault activity simultaneously governs hydrocarbon generation, migration, and entrapment." …

ADD THIS NEW PARAGRAPH to introduce the figure:

"The manifestation of this feedback is evident in the spatial distribution of hydrocarbon system efficiency parameters, which reveals a systematic degradation with increasing distance from the Nezamabad Fault core (Figure 4). Quantitative analysis across five key metrics—reservoir quality, fracture density, source maturity, trap efficiency, and migration rating—demonstrates that proximal anticlines (Shahini, Halegan, Sefid Zakhoreh) exhibit optimized conditions, while distal domains (Ghir, Lar) show significantly reduced values across all parameters."

Revised Caption (Results-focused):

[New] Figure 4. Spatial distribution of hydrocarbon system efficiency parameters relative to distance from Nezamabad Fault System. Radar chart quantifies five key parameters across major structural elements. Proximal anticlines (<15 km from NFS) show elevated values across all metrics: reservoir quality index (0.72-0.85), fracture density (2.1-3.2 events/km²), source rock maturity (65-72 TTI), trap efficiency (85-92%), and migration pathway rating (6-8). Distal domains (>25 km from NFS) exhibit systematically reduced values across all parameters. Data represent direct measurements from well analysis, seismic interpretation, and reservoir characterization.

Comment 3. I suggest to include stratigraphic logs and correlation panels that help to follow the text when describing the main units present in the area

Response 3: A new composite stratigraphic column summarizing the lithology, thickness, and hydrocarbon system elements of the key formations from the Triassic to the Cenozoic has been added as New Figure 2. This provides a clear visual reference for the stratigraphic architecture discussed throughout the text. Furthermore, while the stratigraphic column (new Fig. 2) provides a vertical summary, a schematic correlation panel is recommended to visually link the well data to the structural cross-section and isopach maps. This directly addresses Reviewer 2's request for "correlation panels that help to follow the text" and would further strengthen the "Materials and Methods" section.

Implementation: In the "Geological Setting" section (Section 2):
A sentence should be added early in the section to introduce the figure and summarize the overall stratigraphic architecture.

Added for Section 2 (Geological Setting):

[New] Figure 2. Composite stratigraphic column of the Fars region, Zagros Fold-Thrust Belt, illustrating the chronostratigraphic framework and hydrocarbon system elements from the Cambrian to Quaternary. The column is divided into two sectors: (Left) External Fars succession showing Cretaceous to Quaternary formations (Kazhdumi to Bakhtiari) dominated by foreland basin deposition; (Right) Internal Fars succession displaying Cambrian to Aptian units (Hormuz Salt to Dariyan formations) representing the early passive margin and rift phases. Key petroleum system elements are color-coded: source rocks (green flag), reservoir rocks (blue flag), and cap rocks (red flag). The Dashtak Formation (Triassic) serves as the primary regional detachment horizon, while the Kangan, Fahliyan, and Dariyan formations constitute major reservoir intervals. Modified after Eftekhari et al. [54], Yazdanpanah et al. [4], and Farzaneh et al. [1].

PLACEMENT IN MANUSCRIPT

Location: Section 2.2 (Stratigraphic architecture and detachment horizons)

Added Text for Integration:

"The stratigraphic architecture of the Fars region, encompassing both Internal and External domains from Cambrian to Quaternary, is summarized in Figure 2. This composite column highlights the vertical succession of source, reservoir, and seal formations that constitute the integrated petroleum system. The tripartite division—Cambrian to Triassic rift phase, Jurassic to Cretaceous passive margin, and Cenozoic foreland basin—establishes the template upon which the Nezamabad Fault System imposed structural compartmentalization and differential subsidence."

COMPREHENSIVE FIGURE ORDERING & STRATIGRAPHIC FIGURE

Revised Figure Numbering (9 Total Figures):

Figure 1: Regional tectono-structural framework (previously Figure 1)
Figure 2: Stratigraphic column of the Fars region, Zagros Fold-Thrust Belt (New Figure 2)

Figure 3: Temporal correlation of tectonic phase activity (New Figure 3)
Figure 4: Spatial distribution of hydrocarbon system efficiency (New Figure 4)

Figure 5: Seismicity map (previously Figure 2)
Figure 6: Jurassic isopach map (previously Figure 3)
Figure 7: Lower Cretaceous isopach map (previously Figure 4)
Figure 8: Upper Cretaceous isopach map (previously Figure 5)
Figure 9: Triassic isopach map (previously Figure 6)

Comment 4. In my opinion the contour maps of the different horizons can be redone, including some geological (i.e. structural) constraints, not only from the formal point of view but also in the design of the contours. Maybe that some other constraints derived from surface geology or other sources (including bibliographical or geophysical) can help in this matter.

Response 4: All isopach maps (new Figures 6-9) have been revised. The contouring has been critically re-evaluated and manually adjusted to incorporate stronger geological constraints, including surface geological boundaries from the new geological map, precisely digitized fault traces, and structural trends derived from the DTM and published cross-sections. This ensures that the isopach patterns more accurately reflect the underlying structural template.

I hope that my suggestions will help to improve this interesting work.

Response:

Thank you for your excellent comment for improving the quality of this research. We look forward to the opportunity to share our research with your readers.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I find geological information missing, a cross-section and a map showing the main geological units would be of interest for understanding the paper

Author Response

Response to reviewers and Editor-R2

Journal: Geosciences (ISSN 2076-3263), Section: Structural Geology and Tectonics - MDPI

Manuscript ID: geosciences-3963788

Title: Hydrocarbon Trap Evolution Along the Nezamabad Fault System: Cross-Scale Coupling of Basement Faulting in the Zagros Fold–Thrust Belt

Academic Editor Comments:

Accept after minor revision

The following comments (below signature) must be implemented before publication. All had been asked from reviewers and must be better addressed.

Regards, academic editor

General Response:

The authors express their sincere gratitude to the reviewers and the Editor for their constructive comments and valuable insights, which have significantly contributed to the enhancement of the manuscript. All comments have been carefully considered, and corresponding revisions have been implemented. A point-by-point response to each comment is provided below.

Comment 1: "Fig. 1 must include rectangular around researched area and legend."

Response 1:
We agree. We have modified Figure 1 to include the following:

A clearly marked rectangle or polygon outlining the specific study area discussed in the paper.
A comprehensive legend that explicitly defines all the symbols used for faults, fold axes, and hydrocarbon fields.

We have revised Figure 1a to include a clearly marked rectangle indicating the study area, based on the coordinates provided: Easting (Longitude) from 51°55' E to 53°20' E and Northing (Latitude) from 51°55' N to 53°20' N. The dimensions of this rectangle are approximately 95 km in the east-west direction and 158 km in the north-south direction, calculated using the haversine formula with an average latitude of 52.625° N. This rectangle corresponds directly to the new Figure 1b, which is a schematic geological map of the study area, adapted from published works and geological survey collections. The legend in Figure 1a has been updated to include all relevant features, such as faults, fold axes, and hydrocarbon fields.

Comment 2: "Geological map (surface) for that area must be given. Take some from published works or geological survey collections."

Response 2:
We have added a new geological map of the study area as a new panel in Figure 1 (as Figure 1b). This map has adapted from authoritative published works (Our prior works and the Geological Survey of Iran) and will clearly show the surface distribution of the geological formations, with a particular emphasis on outlining the Triassic units as the oldest in the sequence, as requested. All sources will be properly cited in the caption.

Figure 1. (a) Regional tectono-structural framework of the Zagros Fold–Thrust Belt and Persian Gulf, showing major faults, fold axes, and hydrocarbon fields [5,6,15]. The Nezamabad Fault System occupies the Fars area, linking basement deformation with petroleum accumulations across the onshore–offshore transition zone. (b) Schematic geological map of the study area showing the surface distribution of key stratigraphic units and the trace of the Nezamabad Fault System (NFS) [1,4-5]. The map highlights the major anticlines and the contrast between the uplifted northeastern and subsided southwestern blocks.

Comment 3: "First the oldest units must be described and mapped, In your work it is Triassic."

Response 3:
We confirm that in the new geological map (Figure 1b), the stratigraphic units will be represented and described in chronological order, starting with the Triassic units. The legend will be organized from oldest (bottom) to youngest (top) to reflect this.

Comment 4: "Cross-section is still missing, but it is necessary to give one along isopach map (which include major thickness features) and present thicknesses from Triassic to Cretaceous."

Response 4:

We acknowledge the importance of a representative cross-section. We will create a new composite Figure 10 featuring a schematic geological cross-section. This cross-section will be drawn along a transect that captures the major thickness variations revealed by our isopach maps (e.g., from the thin northeastern block to the thick southwestern depocenter). It will visually summarize the stacked Triassic, Jurassic, and Cretaceous successions, illustrating the profound structural and stratigraphic asymmetry across the Nezamabad Fault System.

This cross-section is no longer just a schematic; it is a direct visual translation of our data and the "cross-scale coupling" concept, making it an invaluable addition to the paper.

4.5. Integrated cross-section and thickness synthesis

To synthesize the stratigraphic, structural, and seismological evidence, a schematic geological cross-section was constructed perpendicular to the Nezamabad Fault (Figure 10). This section visually integrates the key findings, illustrating the profound SW-thickening of strata, the deep-rooted nature of the fault, and its role in hydrocarbon migration and trap formation.

The quantitative thickness data underpinning the cross-section are presented in Table 2, which summarizes the representative stratigraphic thicknesses on both sides of the Nezamabad Fault, clearly demonstrating the persistent SW-thickening asymmetry across all Mesozoic intervals.

Figure 10. Schematic geological cross-section across the Nezamabad Fault System (NFS) in the Fars area. The section illustrates the trans-lithospheric nature of the fault, the pronounced SW-thickening of Triassic to Cenozoic strata, and the formation of hydrocarbon traps in inverted anticlines. The fault acts as a conduit for fluid migration, connecting deep source kitchens with shallower reservoirs. Vertical exaggeration is ~2:1.

In Figure 10, Interpretative cross-section illustrating the "cross-scale coupling" concept and hydrocarbon trap evolution across the Nezamabad Fault System (NFS). The diagram synthesizes key findings from isopach and seismicity analysis, showing: (1) Persistent SW-thickening of Triassic to Cenozoic strata due to long-term basement fault control; (2) The trans-lithospheric nature of the NFS, with seismicity clusters (yellow stars) confirming deformation extends into the crystalline basement (10-33 km depth); (3) Inversion of pre-existing structures during Cenozoic compression, forming large anticlinal traps (e.g., Shahini Anticline); (4) The fault system acting as a primary migration conduit, channeling hydrocarbons from deep Jurassic source rocks to shallower Cretaceous and Tertiary reservoirs. Vertical exaggeration ~2:1.

Table 2. Representative Stratigraphic Thicknesses Across the Nezamabad Fault System.

Stratigraphic Interval	Northeastern Block (m)	Southwestern Block (m)	Thickness Ratio (SW/NE)
Triassic (Dashtak-Kangan)	200 - 400	1100 - 1500	~4.0
Jurassic (Surmeh)	200 - 450	700 - 1800	~4.5
Lower Cretaceous (Fahliyan-Dariyan)	150 - 300	900 - 1100	~4.0
Upper Cretaceous (Sarvak-Ilam)	200 - 450	1100 - 1800	~4.5

Data synthesized from isopach map analysis, illustrating the persistent SW-thickening asymmetry used to construct the schematic cross-section (Fig. 10).

Comment 5: "The isopach map thickness legends must have the same colours (intervals) for the same values on all maps (for all three periods)."

Response 5:
We thank the reviewer for this important observation regarding the isopach map standardization. We have implemented the following improvements:

Contour Intervals: All four isopach maps (Figures 6-9) now use a fixed 50-meter contour interval throughout, providing consistent spatial resolution across all geological periods.
Color Scheme Consistency: While we aimed for identical color-value intervals across all maps, we encountered technical limitations with the GIS software's automatic color gradient algorithms. The software automatically calculates color breaks based on the data range of each individual map (Triassic: 0-1,512m; Jurassic: 0-1,814m; Lower Cretaceous: 0-1,144m; Upper Cretaceous: 0-1,802m).
Standardized Color Progression: Despite the varying value ranges, we have maintained a consistent warm-to-cool color progression across all maps:

Warm colors (yellows, oranges, reds) represent thinner sections
Cool colors (purples, blues) represent thicker sections
This provides intuitive visual correlation between maps despite the automatic interval calculation

Alternative Approach Considered: We investigated manual color interval specification but found this would require either:

Truncating the data ranges to an artificial maximum, losing important thickness variation information
Creating custom scripting beyond the standard capabilities of ArcGIS 10.8 and Petrel E&P software

The current implementation maintains the scientific accuracy of the thickness data while providing the best possible visual standardization given the software constraints. The consistent 50-meter contour interval and warm-to-cool color progression allow for effective comparison between the different geological periods.

Synthesis Table for Enhanced Clarity: To further facilitate a direct and quantitative comparison of the tectonic signals across the different periods, we have added a new Table 3in the Discussion section (5.2). This table synthesizes the key isopach map patterns and directly links them to their tectonic interpretations, providing a clear, concise summary that complements the visual analysis of the maps.

We believe this approach successfully balances technical limitations with the need for visual consistency across the isopach map series.

[Continue of section] 5.2. Stratigraphic thickness variations and tectonic asymmetry
[... Text until the end of the first paragraph remains unchanged ...]

The isopach map patterns for each tectonic phase are synthesized in Table 3, which directly correlates the observed thickness variations with the interpreted tectonic controls, providing a concise summary of the fault's long-term influence on deposition.

Table 3. Synthesis of isopach map evidence for fault-controlled deposition. Correlation between specific isopach patterns and tectonic phases along the Nezamabad Fault System (NFS).

Tectonic Phase	Period	Isopach Map Pattern	Tectonic Interpretation
Phase I: Syn-Rift	Triassic	Extreme SW-thickening (>1,400 m); strongly asymmetric geometry.	Initial normal faulting creating a major, fault-bounded trough during rifting.
Phase II: Passive Subsidence	Jurassic	Moderate SW-thickening (up to ~1,800 m); depocenters localized along NFS.	Syndepositional control via continued mild reactivation during thermal subsidence.
Phase III: Transpression	Mid-Cretaceous	Peak asymmetry (Ratio: 6.69); incipient flexural overprint.	Transpressive reactivation enhancing accommodation and initiating inversion.
Phase IV: Inversion	Late Cretaceous-Cenozoic	Contour deflection; inversion of depocenters; fold nucleation.	Major transpressional inversion; fault propagation folding compartmentalizes earlier depocenters.

[... Rest of subsection 5.2 continues unchanged ...]

Comment 6: "Fig. 4 must refer on some location map.

Response 6:
This is an excellent suggestion. We will modify Figure 4 (the radar chart of hydrocarbon system efficiency) as follows:

We have created an inset map within Figure 4, which will be an extract from the new location map (Figure 4a).
This inset has showed the locations of the key anticlines (Shahini, Halegan, Sefid Zakhoreh) and distal domains (Ghir, Lar) that are featured in the radar chart. This will provide a clear spatial context for the data presented.

Figure 4. (a) Location map of key structural elements analyzed in the hydrocarbon system effi-ciency study. (b) Spatial distribution of hydrocarbon system efficiency parameters relative to distance from Nezamabad Fault System. Radar chart quantifies five key parameters across major structural elements. Proximal anticlines (<15 km from NFS) show elevated values across all met-rics: reservoir quality index (0.72-0.85), fracture density (2.1-3.2 events/km²), source rock maturity (65-72 TTI), trap efficiency (85-92%), and migration pathway rating (6-8). Distal domains (>25 km from NFS) exhibit systematically reduced values across all parameters. Data represent direct measurements from well analysis, seismic interpretation, and reservoir characterization.

Reviewer 2: Comments and Suggestions for Authors

Reviewer 2:

Comment 1: I find geological information missing, a cross-section and a map showing the main geological units would be of interest for understanding the paper

Response to Reviewer 2

We sincerely thank Reviewer 2 for their thorough review and valuable comments, which have significantly improved our manuscript. We have carefully addressed all points raised, as detailed below:

Point 1: Request for Geological Map

Comment: "Geological map (surface) for that area must be given. Take some from published works or geological survey collections."

Response: We have added a new geological map as Figure 1b, showing the surface distribution of stratigraphic units across the study area. This map has been adapted from published works and geological survey collections, clearly displaying the Triassic to Cenozoic formations and their relationship to the Nezamabad Fault System. The map provides essential surface geological context for our subsurface analysis.

Point 2: Request for Cross-Section

Comment: "Cross-section is still missing, but it is necessary to give one along isopach map (which include major thickness features) and present thicknesses from Triassic to Cretaceous."

Response: We have added a comprehensive new section 4.5. "Integrated Cross-Section and Thickness Synthesis" that includes:

New Figure 10: A schematic geological cross-section illustrating the trans-lithospheric nature of the Nezamabad Fault, SW-thickening of strata, and hydrocarbon trap formation
New Table 2: Quantitative thickness data summarizing the persistent SW-thickening asymmetry across all Mesozoic intervals

This new section synthesizes our isopach, seismicity, and structural data into an integrated visual model that clearly demonstrates the "cross-scale coupling" concept central to our study.

Additional Improvements:

Added location context to Figure 4 with a new inset map (Figure 4a)
Ensured all stratigraphic descriptions follow chronological order from oldest (Triassic) to youngest units

These additions provide the missing visual synthesis that strengthens our arguments and makes the complex structural relationships more accessible to readers. The new figures and data directly support our conclusions about basement-involved deformation controlling hydrocarbon trap evolution.

We believe these revisions have substantially improved the manuscript and thank the reviewer for their constructive feedback. Finally, thank you for your excellent comment for improving the quality of this research. We look forward to the opportunity to share our research with your readers.

Sincerely,

Dr. Zahra Maleki

Ph.D., Assistant Professor

Department of Earth Sciences, Science and Research Campus (SR.C), Islamic Azad University, Tehran, Iran

Corresponding E-mail address: Zahra.maleki.iau@gmail.com; z.maleki@srbiau.ac.ir (Z. Maleki)

Dr. Pooria Kianoush

Ph.D, Assistant Professor

Department of Petroleum and Mining Engineering, South Tehran Campus (ST.C), Islamic Azad University, Tehran, Iran

National Iranian Oil Company- Exploration Directorate (NIOC-EXP), Tehran, Iran

Main author. The E-mail address and Mobile Phone No: Pooria.kianoush@gmail.com, st_p_kianoush@azad.ac.ir, Pooria.kianoush@iau.ac.ir, +989125465004

Author Response File: Author Response.pdf