the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 16 Sep 2025
Tectonic control and geometric characterization of hydrothermal vent complex using seismic data, Potiguar Basin – Brazil
Abstract. Hydrothermal vent complexes in sedimentary basins are linked to igneous intrusions, which induce structural and thermal perturbations, causing forced folds, hydrocarbon maturation, and fluid remobilization. While their genesis is often associated with magmatic heat and hydraulic fracturing, the controlling factors of their geometry and development remain debated. This study analyzes 3D seismic data from the Potiguar Basin (onshore Brazil), identifying vent structures, two of which were extracted in a 3D perspective from the variance attribute. Our results indicate that all the vents are structurally controlled by regional-scale faults, which enhance permeability starting from the hydraulic fracturing and boiling processes. Seismic attributes, such as variance and dip illumination have proven effective in identifying vent structures, fault associations, and fluid pathways, providing insights into their spatial distribution and geometric characteristics. Cosine of phase attribute reveals that hydrothermal vents exhibit varying geometries as they cut different sedimentary units within the basin. Our findings highlight the petrophysical implications of a fault zone in a hydrothermal vent complex and advance understanding of silicification processes in sedimentary reservoirs.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2025-3487', Anonymous Referee #1, 21 Nov 2025
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AC1: 'Reply on RC1', Lorenna Oliveira, 12 Dec 2025
Reply to Reviewer 1
We sincerely thank the reviewer for his/her comments and constructive criticisms.
We are confident that these suggestions will significantly help us improve our study.
Below, we provide a point-by-point reply to all the reviewer’s comments.We appreciate the reviewer for also highlighting the paper's limitations and weaknesses,
which we have carefully addressed.Based on this revision, we will specifically reshape the Introduction and regional
context to provide further evidence of the hydrothermal nature of the vent structures.
We have strong evidence from both solid seismic observations and field geology
analysis that supports assigning these subsurface structures to hydrothermal vents.
Please find attached here the supplement document that we organized following the main comment line by
line, with the reviewer comments and suggestions highlighted in italic black
and our answers in blue.Kind Regards,
Lorenna Sávilla Oliveira
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AC1: 'Reply on RC1', Lorenna Oliveira, 12 Dec 2025
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RC2: 'Comment on egusphere-2025-3487', Sarah Weihmann, 30 Mar 2026
Title: Tectonic control and geometric characterization of hydrothermal vent complex using seismic data, Potiguar Basin – Brazil
Author(s): Lorenna Sávilla Brito Oliveira et al.
MS No.: egusphere-2025-3487
MS type: Research article
The study aims to relate tectonic controls and geometric characterization to vent complexes within a shallow sedimentary basin in Brazil, with the objective of advancing understanding on fault zone implications and silicification processes. To achieve this, the authors analyse a regional seismic dataset using a range of seismic attributes.
While my in-depth expertise in seismic analysis on vent structures is limited, it appears the manuscript addresses a relevant scientific question within the scope of SE. That said, it does not seem to introduce a clearly novel concept or lead to particularly substantial conclusions. The title does not fully reflect the content of the manuscript, and it would benefit from a more concise abstract and a more coherent summary. While the overall structure is sound, the central message is not always clearly conveyed. The language is generally fluent and precise, with only minor issues. The reference list includes surplus entries. Expanding and clarifying the figure captions would further improve the manuscript.
Overall, the scientific significance is presumable high, while the quality of the manuscript and presentation quality could be approved upon.
General comments
- Manuscript appears a little unfinished, drafty
- Language could be more fluent
- Figures need better addressing and need to back up the storyline/conclusions better
- Storyline could be more consistent (research questions, study aims, results)
- Tense changes must be avoided
- At times it remains unclear if findings relate to own work or refers to others.
Specific comments
- Figures need to be better aligned with title, storyline and conclusion, e.g.
- Figures do not show specific geometric characterization (Fig. 1) of vents
- Figure captions should e.g.
- refer to apparent faults below (but also sometimes within) vents
- suggest a storyline on location, structure and controls
- Text, abstract and title need to be better aligned.
- Weak link of geometry/vents – e.g.
- “making the geometric characterization of the vents difficult” (528/529)
- “noise in shallow sedimentary sections limits geometric precision” (559)
- Weak proof for link of tectonics/vents – e.g.
- “The association of vents with regional fault systems suggests their formation is intrinsically linked to the basin’s rift-related tectonic framework” (547/548)
- “Although previous studies suggest [otherwise], we highlight that the development of brittle structures such as faults plays a crucial role in this process” (483-487)
- Are vents fundamentally controlled or guided by faults? (543)
- Silicification processes in sedimentary reservoirs should be covered in more depth if mentioned as findings in the abstract (40).
- Weak link of geometry/vents – e.g.
- References need to be checked again (e.g. Bahorich & Farmer 1995 is not quoted in the text)
Technical corrections (and other comments) line by line:
Line 22: Spelling: Correspondence
Line 31: Variance attribute comes sudden and without explanation and introduction. Please introduce and link better.
32: Delete “the”. Generally, the language style would benefit from using less articles.
32: Generally, the language style would benefit from abandoning first person plural (we, our, us..) and keeping it neutral instead (results show..)
33: Delete “the”
33: “enhance permeability” – How? Proof?
33/34: “starting from … boiling processes” - What does this mean? What are boiling processes?
37: Grammar: Article missing
38: Please don’t use first person plural, change to indirect speech
39-41: Petrophysical implications are not mentioned again after the introduction (line 47). The claim needs more substance.
Silicification processes are not mentioned again after the geological setting (line 201). The claim needs more substance.59: Gas, mixed fluids, hot water: All of them are fluids. Reword?
61-66: First sentence is incomplete or lacks depth. Combine sentences? E.g. “While hydrothermal vents are associated with igneous intrusions, their processes and rock parameters, controlling pathways and conduit architecture, remain poorly understood.”
82/84/88/89/ Fig 1: Swap images 1A and 1B to fit the text flow.
83: Change have to has
83: “concordant, divergent or truncated patterns” – is not identical with description in Fig 1; Generally, please incorporate figure descriptions more detailed and precisely in the text.
106: Delete second “the”
109: Add: “In several studies…”
125-127: “To answer the above questions” - This is too strong. Unless all above questions are fully answered by this study (mechanisms of propagation and nucleation, link to preexisting fault zones, controls on final architecture, dependence on overpressure-drive intrusive mechanisms, re-exploitation of existing architecture, influence of host rock properties on architecture development), this should not be worded like this.
127: Grammar: Tense change. Stay in one tense! Present tense is recommended.
129: Use indirect speech please
130-131: Write numbers up to eleven in words rather than numbers.
132: Delete “the”; Use indirect speech please.
134: Add “that”
135: Delete “the” (2x)
135: Delete “and”
127-138: This paragraph on study aims does not fit the questions raised in lines 116-124
142-145: This phrase is overloaded. Possibly split for better reading flow.
149: Fig 2A/B: Arrows clutter the figure. Please use lines. Fit scale in bottom right corner matching Fig 2C. Fig 2C suggests focus on water and Paleogene from colour choice. Better balance weight of colour. E.g. checkshot well: black (why green?); highlighted features: solid colours only (why water?); related features: colour families (why water and Jandeira formation blue?); 3D seismic: black patterned area (why pink outline?); 2D seismic line: black (why dark red?).
171: Grammar: Align tenses
186-190: Please rephrase, paragraph reads poorly and unstructured. When mentioning three events, number them accordingly (e.g. 1), 2), 3) or first, second, third), and structure them by theme, here time, to create a better storyline.
191: “On the surface of our study area” – geographically, thematically, geologically? Adjust wording.
191: Grammar: pipe structures
192: “described before” – Where? Reference please.
200: “This study highlighted – Change tense please. Which study is being referred here? Their own? Menezes’? Very unclear.
204+278 + 446: Consecutive headers should generally be avoided – Possibly introduce a sentence here?
208: Use indirect speech please
211/212: How near? More precision appreciated, Fig 2B shows identical location
212: Tracked changes dash
213/214: Word more clearly please (e.g. “…crosslines with orientations in NW-SE…”)
215: Delete “a”
219: Grammar: Change attributes to attribute
220-222: Reader guidance in subchapter could be improved by suggesting that the attributes are being discussed next.
243+251+257: Use indirect speech please
243-255: To improve structure of the text please mimic structure from 233-242
280/281: This is not a result, please delete
282: Delete “and described” – it adds no context
283: Why is Fig 3A not mentioned in the text? Add please.
284/288/289: Capitalise letter as in all other figures to stay consistent (b to B; a to A)
Fig 3: Change vents to vent
304: Why do the “chaotic patches” (scientific vocabulary please) imply secondary processes?
307/309/319: Use indirect speech please
307: Better: Suggesting the main columnar vertical seismic facies intruding the main seismic package present deteriorated seismic signal, the primary reflections either are absent or very weak, showing edge discontinuities and attenuation of the reflectors.
311: Better: Some of these structures, both along inlines and crosslines, are…
315: Change low-permeable to low permeability
317: Delete “Therefore”, it doubles with instead
321: Change sentence order: Interestingly almost all figures show upward convex deflection of the main reflectors within all columnar areas of the disturbance zone.
323: Change to …with different degrees of…
324: Grammar: Change zone to zones
331: Spelling: Change disturber to disturbed
331: Use indirect speech please
337: Word: Change to case study
337: Delete “all those”, it is colloquial
344: Use indirect speech please
345: Grammar: Change “which are” to “a”
347: Grammar: Change affecting to affect
348/349: Avoid repetition of words (here: “suggest”)
351: Use lines instead of arrows to improve figure clarity
356: Better: …increase in width to the top, crossing all formations…
358: Use indirect speech please
359: Better: …increase in lateral…
362: Use lines instead of arrows to improve figure clarity
367: Where is figure 8A described?
372: Change seismic answers to seismic responses
373/374: Delete “the”
375: Delete “answer”
375: Grammar: Change cover to covers
376: Sentence structure: …vent structures, and the dead mixed zones from the fluid pipes entirely…
377: Where is figure 9A described?
378: “loses” - What does this mean?
380: Delete “automatic”
381-384: Please rewrite, this reads without spirit
391: “delimited” - What does this mean?
391-394: Sentence structure: The vertical and lateral continuity of the pipe anomalies, cause by the seismic signal, becomes more visible with the application of…
395: Show the Christmas tree, else it’s not credible
399: Where is the Christmas tree in the figure?
403/405: Repetition, please find better wording
404: Grammar: zone connects or penetrates
406: Wording: reveals a more complex geometry
411: Sentence structure: (B) to end of sentence
415: Spelling: wipe
416: Grammar: consists
417: Grammar: zones’
419: Grammar: structure
419: Delete “the”
420: Grammar: structure
421: Use indirect speech please
421: Spelling: graph
422: “due the comparison” - What does this mean?
430: Where is (C) described in caption?
435: Use indirect speech please
440: Consistency: “V2 pipe” but “V1 graph”?
442: 1.8x2 = 3.6
443: Change to V1 and V2?
444: Delete “to”
452/457: Use indirect speech please
453: Spelling: reflector
463: Fig
468/469: This sentence seems to make no sense like this
477: Grammar: vent’s
478-483: Rewrite: This is too vague and covers too many keywords/buzzwords at once. Currently it also states that fluid flow acts as seals.
480-486: Reads like a repetition of the sentence before and again is very vague. Please add more precision.
485: Use indirect speech please
487: Delete “the”
492: Coherence: the text mentions faults; the figure mentions fractures
499: Change generation with development
504: Better: in vent characterization
505: Better: Hydrothermal vents are described by inner and outer zones…
508: Better: …allow for the characterization of fluid zones…
511: Delete “the”
514: Use indirect speech please
516/517: Reword “but even with this, it is impossible”
517: Missing verb: as?
519: It is found that the data… (this is not the conclusion!)
519/520: States a very obvious fact. This is hardly a suitable result.
522: Sentence structure: An artifact is not a geological feature.
523/526: Use indirect speech please
532/533: “and vent complex areas as disturbed zones”? - What does this mean?
533/534: …the presence of noise…and is very impacted to noise… - What does this mean?
538/542: Use indirect speech please
539/543: Contradiction in the role of faults: fundamentally controlled vs. guide
540-543: Confusing content: Which previous models? It was not aim of the manuscript to prove that vent formation is solely(?) attributed to hydraulic fracturing(?). Why “Instead?” if the above was a conclusion?
544: Hydraulic fracturing is not the same as fault zones
544-546: “hydrocarbon migration” was not discussed in the manuscript; “reservoir permeability” was not the aim of the study;
552: “Interplay” does not suggest order
Citation: https://doi.org/10.5194/egusphere-2025-3487-RC2 -
AC2: 'Reply on RC2', Lorenna Oliveira, 10 Apr 2026
Reply to Reviewer 2
We sincerely thank Sarah Weihmann comments and constructive criticisms. We are confident that these suggestions will significantly help us improve our study.
Below, we provide a point-by-point reply to all of Sarah Weihmann’s comments. We appreciate her for also highlighting the paper's limitations and weaknesses, which we have carefully addressed.
Based on this revision, we improved the Introduction section to make the paper's questions and results more consistent. Additionally, we revised the language to improve tense consistency for greater fluency, modified the figure captions to better address the figures, organized the paper's storyline, and refined the conclusions. We have strong evidence from both solid seismic observations and field geologic analysis that supports assigning these subsurface structures to hydrothermal vents.
- To be clear, we organized the attached document line by line following the main comment, with Sarah Weihmann's comments and suggestions highlighted in black italic and our answers in blue.
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- 1
Dear authors,
I reviewed your work with interest and on the back of comprehensive experience on both Equatorial Brazil and fluid-flow processes on continental margins.
Unfortunately, I found this paper not mature enough to be published. It seems also to be based on a thesis of some kind - either a MSc or PhD thesis, I am not entirely sure. This means that the paper is overly wordy, its introduction is unfocused, and quantification is lacking in this submission. I stress that just the (presumed) imaging of a vertical dim zone, or spot, in seismic data is not a sufficient condition to publish on Solid Earth. Compounding this limitation, there are interpretation errors in the paper that make me critical about the main conclusion of this work.
Major points (please, see attached .pdf file):
Title - I am not sure if you are dealing with a hydrothermal vent complex in the study area, or just the remnant of an older complex. There are aspects in the interpretation (commented later on) that are puzzling to me, as a reviewer.
1-Line 32 claims that all the vents are controlled by underlying structures. Yet, none of the maps presented in this paper undertakes a mapping of faults and other structures at depth. In other words, the link between structures and fluid-flow features is not established at all in this paper.
2-Line 33 mentions processes such and hydraulic fracturing and boiling (?), but none of these processes can be corroborated by only interpreting seismic data. Such a statement is speculative.
3-Lines 46 and 47 - I am not at all sure what the first sentence in the Introduction means. It means nothing as currently written.
4-Lines 50 to 52 - These lines (and many others after this part) confuse igneous intrusions with hydrothermal vents. Vents are seeps of volatiles and fluid. Intrusions are, essentially, formed by viscous hot magma that forces its way into the surface, or into a sill, lacolith or other intrusive igneous body. The two processes should not be mixed.
5-Volcanic or magmatic? Volcanic processes imply the formation of volcanoes at the surface.
6-Line 57 - What reservoirs? Magma reservoirs? Fluid reservoirs?
7-Line 61 is redundant.
8-I do not know what is post-mortem seismics. Surely many a seismic survey and marine geology campaign have sampled and surveyed ACTIVE hydrothermal seeps.
9-Lines 66 to 68 - This statement is incorrect as Chris Kirkham, C. Roelofse and other authors have concluded on the mechanisms that lead to the nucleation and propagation of vents. There are many papers from Marine Geology surveys that explain these same processes too.
10-Page 4 reads as a literature review.
11-Line 102 to 115 mention aspects, and results, that are not novel at all. Your attribute-based methods have been used for decades, so they cannot justify the publication of this paper alone. What are the geological research questions you intend to address?
12-Lines 116 to 124: If these are research questions of your interest, there are three main processes indicated in this paragraph which, for better or worse, cannot be addressed by seismic data alone. They are completely out of the scope of this paper.
13-Line 130 reveals that your dataset is very small. Twelve fluid-flow features are not a hydrothermal vent complex. Actually, only 3 of these features are (tentatively) interpreted as vents.
14-Lines 191-192: A silicified fault zone is evoked here. Yet, none of the maps and surfaces shown (nor the seismic profiles) show a unequivocal fault zone. The paragraph on this page 9 calls no figures or data to corroborate the presence of such a fault zone.
15-MAJOR ISSUE: being the features on Figure 4 interpreted as vents and pipes, why have they completely flat tops? As (rightly illustrated by Figure 1, you should see craters, domes, eye-shaped, onlapping, divergent, etc., etc. geometries above your vents. Yet, the seismic data in Figure 4 show completely flat continuos reflections across the putative vents and pipes. Moreover, the seafloor is flat.
16-Some of the faults in the profile may actually be artefacts and or push-down and pull-up acoustic features.
17-Figure 5- Another example of completely flat tops for the putative vents + continuos reflectors across them. Please, compare your features with those documented by Chris Kirkham and Chantelle Roelofse. Figure 6 show more flat tops. Are you in the presence of dim zones, rather than vents and pipes?
18-The remainder of the paper is well illustrated, but none of the figures is based on a solid interpretation work. Also, structural maps are lacking to tie the deeper structures to the imaged dim zones. These are dim zones, not pipes and vents, in my opinion. Unless you had an issues during seismic acquisition and acoustic signal was lost at some point - or there are carbonate/hardened features on the seafloor that 'dim' the strata below. The bottom line is that these are dim spots and zones, not fluid vents and pipes that have forced their way onto the seafloor, which is flat and undisturbed by this putative fluid flow.