the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 28 Jul 2026
Why are plate suture zones on the Tibetan Plateau hotspots for rockslides: A case study of Jinsha River area
Abstract. Tectonic suture zones on the Tibetan Plateau, as structurally weak belts, commonly host numerous large to very large rockslides. However, how the material composition and structural architecture of suture zones govern the initiation and evolution of landslides remains poorly understood. This study focuses on the Jinsha River suture zone (JSSZ). Through systematic field geological investigations, laboratory microstructural analyses, and landslide inventory statistics, we elucidate the control of tectonic mélange belt lithology and structure on landslide development, and construct a four-stage dynamic conceptual model from initiation to triggering. The results indicate that the heterogeneous, weak lithologies and complex structures of the suture zone provide the fundamental material and structural basis for landslide initiation. Sliding surfaces are not randomly distributed but predominantly localized along sub-horizontal foliation planes or lithological interfaces. These pre-existing discontinuities, under tectonic uplift and river incision, become preferential pathways for stress release and progressive weakening, resulting in clustered landslide distribution along the suture zone. Accordingly, a four-stage initiation and evolution model is proposed, systematically explaining the complete dynamic process from suture zone formation establishing the material-structural framework, through tectonic uplift and river incision driving rock mass fracturing, freeze–thaw cycles and chemical weathering causing progressive coalescence of the sliding surface, to final triggering of catastrophic failure. This study reveals the fundamental control of suture zone lithology and structure on landslide initiation, shifting the analytical perspective from short-term triggers to long-term dynamic coupling, and from external driving conditions to intrinsic lithological-structural constraints. The findings provide a new theoretical framework for understanding clustered rockslide development on the Tibetan Plateau and similar active orogenic belts, and offer a material-structure-based assessment basis for major engineering site selection and early risk identification.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2026-3016', Anonymous Referee #1, 07 Aug 2026
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RC2: 'Comment on egusphere-2026-3016', Anonymous Referee #2, 14 Sep 2026
The paper by Zhou et al investigates two large rockslides in the Jinsha River area through field surveys and thin section analyses, to decipher the factors controlling landslide occurrence, ultimately proposing a theoretical framework. The topic is certainly of interest to the journal audience, however I think the paper requires major revisions to meet the criteria for publication.
The conclusions are ambitious and far-reaching, but the data presented here do not fully support such claims. An explicit definition of suture zones is lacking; by definition, tectonic melanges are highly heterogeneous, so a proper definition of the type of settings that can be analyzed using the proposed framework is relevant.
I think some rephrasing and providing more nuanced statements (e.g., last part of the abstract) could better reflect the paper contents. Indeed, the authors present their work as a new theoretical framework. If this is the case, the authors should better explain which is the novel content of the proposed framework and why the Jinsha river area is a reliable place to develop such framework. Moreover, their interpretations are based on 2 field sites only, which may be not enough to grasp the variability of the involved processes.
Results: I agree with Reviewer 1, there is a gap in the description of the macroscopic features before moving to the micro-scale. The observations and interpretations (e.g., lines 163-166; 178-183) are not adequately supported by the presented data – the reader simply has to believe in the authors’ claims. I suggest improving section 4.2, by providing a more thorough description, quantitatively supported by e.g., stereoplots or density contours of the joints and fractures. A more detailed description of the spatial setting of the 2 study areas is required, possibly including a detailed geological map.
In section 4.3 and Figure 4, a few examples of thin section microphotographs are provided; however, it is not clear from which of the 2 study sites they are sampled. No samples outside the landslide areas are shown – this fact prevents the possibility of evaluating the robustness of the authors’ interpretation. Indeed, if the rock properties in the suture zone within and outside the mapped landslides are similar, the proposed framework would not be supported.
Discussion: the interpretations described in the discussion section are reasonable, however the authors should explicitly mention which aspects of the study region are expected elsewhere and which other aspects are specific of the Jinsha River suture zone. Is the theoretical framework expected to be applicable on a global scale? Only where disrupted tectonic mélange is present? Only where high uplift rates dominate the landforms? Only where river incision is prominent?
Line-by-line comments
Lines 25-27. The last sentence of the abstract is quite ambitious. I suggest rephrasing, to be more consistent with the achieved results and implications.
Lines 38-39. Provide an explicit definition of plate suture zone. Do they represent merely the geographic boundary between different tectonic provinces? Does the definition include a seismotectonic perspective, or a lithological one? How are the boundaries defined with respect to external zones?
Lines 94-96 and figure 1b. Is the seismicity represented in Figure 1b the instrumental catalogue or the historical catalogue? Which is the time interval covered by the catalogue? Moreover, seismicity in figure 1b seems highly clustered: which are the implications of such an observation, e.g., in terms of rock properties or weakening of hillslopes?
Section 3.1. Since you aim at providing a theoretical framework of wide applicability, some extra information on the used dataset is required. Which was the methodology used to identify landslides? Is the inventory assumed to be complete over the study area? Are the landslides active? If yes, which is the rate of movement? How was slope gradient calculated – it is the average value of pixels falling within landslide polygons? Which is the resolution of the DEM used to compute the slope?
Line 129. Figures should be numbered in consequential order. It seems you introduce here Fig 3 before introducing Fig 2 at line 142.
Figure 2c-e. I don’t get the meaning of the dots in the pdf curves. I understand they are the individual landslides, but why are they shifted along the x-axis? Is it the distance from the Jinsha river?
Figure 6 panel d: please correct two typos in melting and weathering
Lines 381-382. I definitely agree with this statement; please revise the abstract, the last part of the conclusions and other places where you claim to propose a novel theoretical framework, to be more aligned with the actual content and results of the paper.
Citation: https://doi.org/10.5194/egusphere-2026-3016-RC2
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- 1
Dear authors,
the subject you have been working on, i.e. rockslides in suture zones is certainly of great interest.
However, within your approach there is a clear gap : the analysis of macro-structures before investigating micro-structures.
You jump immediately from regional tectonics to thin section scale .. via a few views of outcrops. But, no results of macroscopic
structural geology shown (stereoplots etc).
Then, you present Fig 6 as a schematic representation of your results - outlining apparently special characteristics of rockslides
in suture zones .. while you could present precisely the same rockslide evolution schemes for major mass movements in the European
Alps, very far away from any suture zones. The missing point .. as you have not analysed macro-structures, those features you show in Fig 6
are most of the times related to toppling, .. which can also locally create shear zones after creep (not related to regional tectonics).
So, for me, without a deep macro-structural analysis you are too much generalising your results, to cover examples that have nothing
to do with suture zones.
yours
reviewer H