Reconciling patterns of long-term topographic growth with coseismic uplift by synchronous duplex thrusting

Domain: earth_science
Published: 2023-12-06
Editorial outcome: minor_revision

Abstract
How long-term changes in surface topography relate to coseismic uplift is key to understanding the creation of high elevations along active mountain fronts, and remains hotly debated. Here we investigate this link by modeling the development of growth strata and the folding of river terraces above the Pishan duplex system in the southern Tarim Basin. We show that synchronous duplex thrusting of two neighboring faults with varying slip rates, associated with in-sequence propagation of the Pishan thrust system, is required to explain the presence of opposite-dipping panels of growth strata on the duplex front, and basinward migration of terrace fold crests. Importantly, this process of synchronous thrusting within the duplex reconciles the discrepancy between the deformation of terrace folds at the 10−1–100 million-year timescale and the maximum coseismic uplift of the 2015 Mw 6.4 Pishan earthquake on the frontal thrust. These results suggest that topography mismatch at different timescales can reflect the long-term kinematic evolution of fault systems. Thus, our study highlights the importance of characterizing complex subsurface fault kinematics for studying topographic growth, and motivates rethinking of the mountain building process in worldwide active fold-and-thrust belts, from short-term to long-term timescales.

Introduction
Topographic growth reshapes the Earth’s surface and affects a wide range of processes such as regional climate patterns and terrestrial biodiversity1–4. In the long term, the growth of topography can be driven by crustal thickening either through viscous deformation at depth or brittle deformation in the upper crust over millions of years and is usually described as a continuous, quasi-steady process5. In the short term, topography can be produced via repeated episodes of coseismic folding and uplift, in particular along fold-and-thrust belts, that in aggregate form high-topography mountains6,7. The relationship between short-term earthquake uplift and long-term mountain building has been hotly discussed for decades, with many studies arguing that high topography is created through repeated coseismic slip8–11; while others look for alternative mechanisms, for instance, from inelastic deformation occurring during interseismic periods, to explain the discrepancy between the positions of repeated coseismic uplift and long-term topographic growth that is sometimes observed (e.g., the 2005 Mw 6.0 Qeshm Island in Zagros, the 2015 Mw 7.8 Gorkha Himalaya, and the 2015 Mw 6.4 Pishan in southern Tarim)12–14. Previous efforts in examining the relationship between long-term topographic growth and coseismic uplift in fold-and-thrust belts relied mainly on surface records of activity of single faults12,15,16. Thrust fault kinematics and geometry (especially for blind thrusts) in the upper crust are in many cases constrained by their relationship with overlying folds17–20. However, the subsurface geometry and detailed kinematics of multi-thrust fault systems, such as duplexes, have been less well explored. In several fold-and-thrust belts where these fault systems have been described, synchronous slip on two or more neighboring faults has been documented21–25. How to detect whether synchronous thrusting occurs, and how such a process affects surface deformation remains unclear, hampering our understanding of the relationship between medium-to-long-term topographic growth and coseismic uplift.

Located at the northwestern margin of the Tibetan Plateau, the Pishan fold-and-thrust belt is a classic duplex system that accommodates the deformation propagated northward from the Tibetan Plateau into the Tarim Basin (Fig. 1)26,27. The tectonic activity of this duplex system has produced a series of earthquakes28–31, including the 2015 Mw 6.4 Pishan earthquake that occurred at the frontal ramp of the duplex and produced coseismic surface folding (Fig. 1d)27,32. However, during this event, the crest of coseismic uplift was misaligned with older fluvial terrace folds above the frontal fault ramp12. Since the long-term growth of fluvial terrace folds cannot be fully explained by repeated coseismic slip similar to that observed in 201512, the discrepancy between the long-term and present uplift has been partly attributed to other mechanisms such as postseismic slip or interseismic inelastic deformation, similar to other active fold-and-thrust belts13,14,33,34.

In this study, we re-interpret a high-resolution seismic reflection profile to describe in detail the geometry of the Pishan duplex system, as well as of a newly identified interval of overlying growth strata. We then combine our observations of the growth strata geometry with previously published terrace folding measurements to develop new kinematic models to describe their formation with the goal of characterizing the evolution of the Pishan duplex. We show that synchronous thrusting of two adjacent faults in the duplex system is required to form these structures. Finally, we propose an alternative explanation for the location mismatch between coseismic uplift and terrace folds, demonstrating how complex subsurface processes play a critical role in generating topography in active fold-and-thrust belts at various timescales.

Results
Observations from the Pishan seismic reflection profile
The geometry of the Pishan fold-and-thrust belt is well imaged by an NNE-striking seismic profile (Fig. 2a, see Supplementary Text S2 for details). This profile can be separated into three sequences by two strong continuous seismic reflections (D1 and D2)26. From bottom to top, the sequences are (1) below D1: a discontinuous and chaotic reflector package denoting the pre-Cambrian basement26,35, (2) between D1 and D2: a continuous and southward thickening reflector package representing Paleozoic strata, and (3) above D2: a continuous and generally north-dipping reflector package representing Cenozoic strata, which comprises the Slik monocline at the duplex front. D1 and D2 are also the lower detachment (rooted in the lower Cambrian), and upper detachment (rooted in the basal Paleogene evaporate), of the Pishan duplex, respectively. The strata between them is deformed by four ramp faults (Fig. 1d) that comprise a duplex thrust system wherein-sequence thrusting has been interpreted36.

Noticeably, the shallow strata in the forelimb of the Slik monocline feature south-dipping reflections above the overall north-dipping reflections that we interpret as an interval of syn-tectonic strata. The lower part of the south-dipping reflections rests on chaotic reflections (L9-14 in Fig. 2c). Moving upward through the stratigraphy, these south-dipping reflections gradually change into a concave-up synform (L14-20 in Fig. 2c). In the shallowest part, the synform reflections become nearly horizontal (L20-21 in Fig. 3c). Generally, these south-dipping and concave-up reflections are spatially restricted by axial surface A to the south and axial surface C to the north, and do not extend to the southern limb of the Slik monocline. The strata in the synform are also slightly thicker than the undeformed strata to the north (Fig. 2). These growth strata record underlying faulting events, but are not produced by fault-bend folding (Figs. S3a and S4a) or by folding above a tectonic wedge (Figs. S3b and S4b), two basic kinematic processes that are generally considered to dominate at thrust fronts19,37.

Modeling results
We use MOVE software to construct novel models of growth strata and terrace fold formation to decipher the subsurface process responsible for the geometries observed above the Slik Monocline, as well as its effect on surface topographic expression. The detailed modeling processes and parameters are provided in the Methods and the Supplementary Information sections.

Growth strata are modeled at the front of a duplex system characterized by synchronous motion of the root and roof thrust faults as they reach the front of the duplex. We use fault models with smooth fault bends, similar to natural examples. The resulting growth strata can be separated into three segments by axial surfaces B and C (Fig. 3a). From north to south, these are (1) an undeformed zone limited by axial surface C to the south, (2) a south-dipping zone located between axial surfaces B and C, and (3) a horizontal to gently north-dipping zone limited by axial surface B to the north. The south-dipping zone rests unconformably on the horizontal pre-growth strata and tapers upward, while the zone with horizontal to gently north-dipping layers onlaps the forelimb of the underlying anticline. These oppositely dipping zones comprise a broad synform at the front of the duplex system. In addition, the growth strata of the synform are systematically thicker than those in the undeformed zone. A similar geometry also forms in models with sharp fault bends and hinge zones (Supplementary Fig. S2).

Such a geometry significantly differs from growth strata in thrust fronts formed by fault-bend folding or wedge structures (Supplementary Figs. S3a, b and S4a, b)37,38, but is similar to those related to listric normal faults (Supplementary Figs. S3c and S4c)38,39. This growth strata geometry reflects the contribution of the roof thrust during the synchronous thrusting of a duplex system. Here, the downward slip of roof thrust between axial surfaces A and B results in the thickening of the growth strata that is initially onlapping on the north-dipping forelimb. Meanwhile, these thickened strata gradually turn to south-dipping as the roof thrust carries them through axial surface B onto the horizontal fault segment. This is similar to the migrating growth strata that is produced as basal detachment fault slips over a bulge on an otherwise planar fault segment40. Therefore, the horizontal distance between axial surfaces B and C represent the amount of fault slip along the roof thrust since the frontal ramp initiated slip (Fig. 3a and Supplementary Fig. S2).

We model terrace folds in a duplex system characterized by synchronous motion of two ramp thrusts with three scenarios: (1) two ramps active with constant slip rates (Model 1; Figs. 3c), (2) the rear ramp slip ceasing in the latest stage (Model 2; Fig. 3d), (3) the frontal ramp slip ceasing in the latest stage (Model 3; Fig. 3e). We compare models of synchronous thrusting to a reference model with a single ramp. Our results show that synchronous thrusting models have wider terrace-fold wavelengths and a slightly more hinterland-ward distribution of fold crests (Fig. 3c–e) compared with the reference model, due to the contribution of the rear ramp (F2) (Fig. 3f). Moreover, variations of slip rates among the two ramps lead to the migration of crests of lower (younger) terrace folds relative to the higher (older) ones. Model 2 shows that crest axes of lower terrace folds migrated forward (northward) relative to those of the higher terrace folds as the rear ramp (F2) slip ceases (Fig. 3d); while Model 3 shows the opposite migration of fold-crest axes as the frontal ramp (F1) slip ceases (Fig. 3e). In contrast, Model 1 with temporally constant slip rates for the two ramps generates nearly the same fold-crest axes (Fig. 1c).

Modeling results also show a small trough on the forelimb of the terrace folds (axial surface Y in Fig. 3c–e) during the synchronous duplex thrusting. These concave-up terraces, analogous to the synform in the growth strata (Fig. 3a), are products of downward slipping of the roof thrust at the forelimb of the anticline, which could lead to the intersection of higher terraces with lower ones in a cross-section view (Fig. 3e). However, this concave-up topography is probably compensated by sediments in the field.

Comparison of the observations with modeling results
By comparing our observations across the Pishan duplex belt with our modeling results, we find that these south-dipping and thickened strata in the forelimb of the Slik monocline are consistent with the geometry of our growth strata model (Figs. 2 and 3a). This suggests that even though the frontal ramp is the most active fault in the Pishan belt, building the Slik monocline and generating a series of recent earthquakes12,41, the roof thrust must have remained active, at least for a period of time, since the frontal ramp was activated. Therefore, the frontal ramp and roof thrust were active synchronously in the long term, although whether the slip is strictly synchronous or movement alternated between the two faults remains unknown. Nevertheless, we propose that most of, if not all, the slip on roof thrust comes from the penultimate ramp fault (F5 in Fig. 1d). This proposition is supported by two observations: (1) the sequential younging of growth strata related to anticline formation towards the foreland across the Pishan belt, as documented in this study (Fig. 1d and Supplementary Fig. S7) and by Liang et al.36, indicating in-sequence thrusting in this duplex system with recent deformation concentrated on the front two ramps, and (2) the presence of uplifted terraces above the first two ramps instead of the antepenultimate ramp (F4), where the crest of an older fold (the Heshitage anticline) is located (Figs. 1 and 4).

The fluvial terrace deformation across the Pishan belt has been well documented after the 2015 M 6.4 earthquake (Fig. 1b)12,41–43. Studies show that fold crests of the lowest (youngest) terraces are about 3–4 km north of the fold crests in the higher (older) terraces and that the forelimb of the fold in lower and higher terrace flights (Tw1 and Tw9) all intersect (Figs. 1b and 4a)12,41. This terrace geometry corresponds to Model 2 of our terrace modeling (Fig. 3d), which indicates that the penultimate ramp ceased or decreased in slip rate relative to the frontal ramp of the Pishan belt during the latest phase of deformation. This inference of variation in slip rates along the two frontal ramps is supported by the shallowest growth strata in the forelimb of the Slik monocline, which becomes nearly horizontal overlying the concave-up strata and probably documents the cessation of slip on the roof thrust (Fig. 2b, c and Supplementary Fig. S8). This result is also consistent with accelerating incision rate across the belt since ~400 ka, a finding that was interpreted to signify a transition from deformation partitioning between the two ramps to deformation concentrating mainly on the frontal ramp41.

Moreover, dating results show that the youngest terrace (Tw1) in Fig. 4a was abandoned at 220 ka12,41, which means the lowest terrace was deformed after the cessation of the penultimate ramp (~400 ka), if the previous dating is correct41. Our modeling results of terrace folds above the frontal ramp by fault-bend folding, are generally consistent with the geometry of terrace Tw1 when the fault slips 100 m (Fig. 4a, see Supplementary Text S3 for details). This consistency suggests that the lowest terrace fold was exclusively controlled by the frontal ramp. Collectively, the Pishan belt documents coeval fault slip on the frontal and penultimate ramps for a period of time that transitions to slip only on the frontal ramp. This synchronous thrusting process probably represents the transition of deformation in an in-sequence duplex system where the hanging-wall ramp does not cease immediately at the onset of faulting along the footwall ramps (e.g., refs. 44,45). In other words, both ramps slip coevally until the older one is abandoned. During this process, the lower (younger) terrace folds gradually migrate basinward relative to the main fold crests due to the deactivation of the penultimate ramp (Fig. 4).

Methods
Growth strata modeling
We use the 2D MOVE software to model the development of growth strata and terrace folding above a duplex system where two adjacent ramp faults transfer slip synchronously. Growth strata are constructed on the front of the duplex system, which is characterized by upward motion over the ramp of the root thrust and downward motion over the roof thrust as it reaches the front of the duplex (Fig. 3a). To model the synchronous duplex thrusting, we design a frontal ramp and a roof thrust, both with constant slip rates, for simplicity. The sedimentation rate is approximately equal to the uplift rate, which is similar to the area of our case study in Pishan. Moreover, this kinematic model was produced using fault-related folding models with smooth (Fig. 3a) and sharp (Supplementary Fig. S2) fault-bends19,37 that assumes no internal deformation of the thrust sheets. In addition, we show growth strata obtained using a model for slip along a single fault in a duplex37 as a reference (Fig. 3b). The details of growth strata models are presented in the Supplementary information (Text S1.1, Table S1, and Fig. S1).

Terrace fold modeling
Compared to growth strata, terrace folds preserve deformation records reflecting the subsurface kinematic process over a much shorter time-scale, but are more sensitive. Here we constructed terrace folds in a duplex system with two detachment layers and two ramp faults in between. Three end-member models (Fig. 3c–e) are presented to examine the relationship between terrace folding and synchronous duplex thrusting, using fault-related folding principles19,37. The models feature (1) two ramp faults active with constant slip rates (Model 1; Fig. 3c), (2) the rear ramp slip ceasing in the latest stage (terrace T1 was abandoned, Model 2; Fig. 3d), and (3) the frontal ramp slip ceasing in the latest stage (terrace T1 was abandoned, Model 3; Fig. 3e). In Models 2 and 3, as slip on one ramp ceases, the other accelerates in slip rate because the total slip rates are constant. Moreover, we simulate the terrace deformation under single-ramp faulting, as a reference (Fig. 3f). The details of terrace fold models are presented in the Supplementary information (Text S1.2, Table S2, and Fig. S5)

Data availability
The uninterpreted seismic reflection profile used in this study is provided in Supplementary Fig. S6. The geological data used to compile the geological map of Pishan (Fig. 1a) are obtained from http://www.ngac.org.cn, which is open to the public. The 12.5 m-resolution digital elevation model data used in the geomorphologic map (Fig. 1b) and topographic profile (Fig. 1c) are obtained from https://search.asf.alaska.edu. Modeling of growth strata and terrace fold are based on the MOVETM software (PE Limited), available at https://www.petex.com. The original modeling results in MOVE format are provided in the Source Data. Source data are provided with this paper.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "Understanding how the high relief along acfive mountain fronts (e.g., around the Tibetan Plateau and\nTian Shan in Asia) achieved is a key quesfion in confinental tectonics. Yet, there exists a long-standing\ndebate on the discrepancy between short-term earthquake uplift and long-term topographic growth, in\nparficular, for fold-and-thrust orogenic belts. In this study, Zhang et al. ufilized novel models of\ndeveloping growth strata and terrace folds by synchronous thrusfing in a duplex system. Then the\nauthors applied the model results into the Pishan thrust belt where show obvious discrepancy between\nposifions of long-term topographic highs and transient earthquake uplift as recorded by the high-\nprecision InSAR results. The synchronous thrusfing explained very well the discrepant posifions of long-\nterm topographic highs (folding crests) and transient maximum earthquake uplift, and provides a new\nand alternafive mechanism for the topographic growth in orogenic belts throughout the world, across\ndifferent fimescales. To my knowledge, this is an excifing and novel finding that will be of broad interest\nto the research community of confinental tectonics, geomorphology, geodesy and even the paleo-\nenvironment. Moreover, the manuscript text has been well wriften, and figures well illustrated. Given\nthe importance and high impact of this study, I strongly support its publicafion in Nature\nCommunicafions.\nHere I have some minor comments on the figures and the reference format, for the authors to consider.\nFig. 1. The interpretafion of thrusfing structure under the Keliyang anficline seems to be inconsistent\nwith the offset across the strata. Although this minor problem will not affect the authors’ interpretafion\non the synchronous thrusfing under the Pishan belt, it needs to be revised.\nPlease place the horizontal axis labels under the numbers, cite the references for the two earthquakes.\nFig. 2a: “syn-sedimentary model” should be “Growth strata development under synchronous thrusfing”;\nPlease show horizontal and verfical axis labels in Fig. 2.\nFig. 3: The labels for horizontal axes of Fig. 3b & 3c should be placed under the numbers and aligned in\nthe middle. Clarify the numbers (3, 4, 5, …, 15, 17, 19 , 21) on the right edge of Fig. 3c in the figure\ncapfion, layer numbers, right?\nFig. 4: Reorganize the fault legend at the boftom of the figure as: Fault type: acfive, ceased recently,\ninacfive.\nAlso, the format of the references (e.g., Refs. 1 - 3) needs to be double checked and revised according to\nthe journal requirement.", "reviewer_2": "In their paper enfitled “Reconciling long-term topographic and transient seismic uplift by synchronous\nduplex thrusfing” Zhang and co-authors invesfigate how the topography in the southern Tarim basin\ngrew and how it relates to the Pishan earthquakes (2015, Mw 6.4) and deep duplex structures. The\nauthors mainly conclude that the surface topography (terraces) is due to slip on a deep blind thrust fault\nof a buried duplex. They also concluded that the recent Quaternary topography was made by the\ncumulafive deformafion/uplift of repeated earthquakes on this blind fault.\nThe quesfion addressed in this study is crifical. The deformafion model is robust, and model results are\nconvincing. The model nicely explains the growth strata at depth and the geometry of the terraces at\nsurface suggesfing that the deformafion mechanism proposed by the authors is realisfic.\nHowever, the main conclusion of the paper that: “the topographic growth in Pishan can be produced\nmainly by repeated individual earthquakes in a duplex system, without the need to invoke addifional\nmechanisms, in certain cases.” is speculafive since not supported by any new data/model etc. It\nmoreover contradicts the previous work by Ascinoe et al. (2017). These authors using InSar, analyses of\nthe same seismic profile together with terraces topography, have already deeply invesfigated the\ndeformafion associated to the Pinshan earthquakes and how it relates to the quaternary topography.\nYet, they concluded: ”over the fimescale of mulfiple earthquake cycles, interseismic and addifional\naseismic deformafion must be invoked”. Yet, to reach this conclusion, Aniscoe et al. modeled the “ground\ndisplacements from elasfic forward models of earthquakes on the detachment“. Aniscoe et al. were “not\nable to account for the anficline by coseismic slip alone”. In contrast, to support their asserfion Zhang et\nal. only speculate (see L212 to 233). Other mechanisms than elasfic deformafion during repeated\nearthquakes should be discussed and invesfigated. This includes interseismic, asismic deformafion,\ncreeping, analesfic buckling/folding etc. Those mechanisms are overlooked by Zhang et al. while they\ncould play a major role in explaining the observed uplift of the terraces at surface and the misfit with\ncoseismic displacement observed during the Pishan earthquakes. Consequently, the statement that they\n“reconcile the discrepancy between the long-term topography of terrace folds and maximum co-seismic\nuplift of the 2015 Mw 6.4 Pishan earthquake on the thrust front” is a bit overrated (so the fitle of the\npaper is).\nMoreover, the novelty of this study is quesfionable which may be an obstacle for a publicafion in Nature\nCom. Indeed, most of the data presented in Zhang et al.’s paper were actually presented by Aniscoe et al.\n(2017) and these authors already reached similar conclusions about the link between long term\ntopographic growth, the Pishan earthquakes and deep deformafion mechanisms. They said that: (1) “the\ncoseismic ground displacements from the earthquake do not align with the anficline in Quaternary\nfluvial terraces”, (2) “Our results show that distributed postseismic relaxafion of the Cenozoic sediments\nafter the coseismic stress change also cannot explain the anficline growth” and hence (3) “The remaining\nmechanisms are therefore slip on different parts of the ramp and flat (parficularly interseismic transport\non the detachment) and internal deformafion of the wedge. Although only a few key faults have been\ninterpreted in Figure 6, both the wedge geometry and the reflecfions show that it has undergone\ninternal thickening in the past and may sfill be doing so.”\nHowever, it is true that Aniscoe et al. remain elusive regarding the deep mechanisms of deformafion\nwithin the wedge that are responsible for the Quaternary topographic growth observed at the surface\nand inferred from terraces topography. Zhang et al explore more deeply these mechanisms using Moove\nsoftware modeling and reached convincing and elegant results. So, the main input of Zhang et al. works\nis a deformafion mechanism at depth.\nAt last, the organizafion of the paper is to my opinion awkward. The authors first describe a structural\nmodel of duplex and propose different scenarii with different kinemafics/fiming of fault acfivafion. Syn-\ntectonics layers are then deposited above the duplex and deformed accordingly to the scenarii. Finally,\nthe authors compare the geometry of these deformed layers to the growth strata observed on the\nseismic line and terraces geometry measured at the surface. But a logical presentafion would have been\nfirst to describe the Pishan duplex system and the geometry of the syn-tectonics layers. Then, based on\nthese observafions, a structural model the deep duplex structures could be proposed accordingly, and\ndifferent fault kinemafics could be tested. The results of the modeling can be then compared to the\nreality to discriminate between the scenarii.\nIn conclusion, I think the results of this paper about the deep long-term mechanisms of deformafion are\ngood and very interesfing, even if they are, to my opinion, not well presented/organized. But I don’t\nthink this study has reached the level quality requested for publicafion in Nature Communicafion\nbecause it lacks novelty and, more importantly, robust data/model to support the main conclusion that\nthe topography was made only by repeated earthquakes.\nI therefore suggest rejecfing the paper.", "reviewer_3": "Review of the manuscript \"Reconciling long-term topographic growth and transient seismic uplift by\nsynchronous duplex thrusfing\" by Zhang and co-authors, submifted to Nature Communicafions.\nIn their paper, the authors establish geometries of growth strata related to ramp acfivity in duplex\nstructures and compare them to seismic lines across the Pishan thrust system in the Tarim Basin.\nFurthermore, they model and invesfigate terrace folding to track shorter term topographic evolufion.\nThe manuscript is well wriften and the topic is of interest for a broad scienfific community. They\ndemonstrate how a rather simple technique (modelling of growth strata and terraces with Move for\nexample) can help understanding complex problems such as long-term versus transient deformafion in\nfold-and-thrust belts. Overall, I think the paper is a nice contribufion and may be published, however,\nafter some re-organizafion of the text. At fimes, I had difficulfies to follow the argumentafion and in my\nview the study would gain a lot if, for example, the study area (incl. Fig. 1) was introduced earlier.\nI hope my comments are useful and construcfive\nComments:\n1) The study deciphers differences between long-term and transient deformafion. As far as I understood,\nthe authors interpret deformafion along duplex thrusts as transient and bulk pure shear deformafion of\nthe lithosphere as long-term. Maybe I understood that wrongly, but then it should be explained more\nclear. Slip along the ramps can also be aseismic, so I suppose the main difference to be invesfigated here\nis localized versus regional uplift or so?\n2) The introducfion is followed directly by the results part. I understand that there are some length\nissues, but whilst reading it was difficult to follow a red line. Furthermore, figure 1 is cited out of context\nat the end of the introducfion, probably to avoid that the results of figure 2 are the first figure. I suggest\nto move lines 123-148, somewhat modified, into the introducfion or even to a new secfion related to the\nstudy area, linked to figure 1. This would help a lot to introduce the zone of interest and put figure 1 into\na more reasonable context.\nMinor comments:\nLine 28: delete nicely\nLine 30 and 32: Be more precise than \"this process\", as it is not clear which one is meant\nLine 33: What would be the alternafive mechanism besides transient or long-term?\nLine 43: explain what a folding event would be. folding within seconds to minutes? Folding = viscous?\nLine 49: inelasfic\nLine 53: would seismic tremor, aseismic slip, or slow slip be transient of long-term deformafion?\nLine 64: Maybe have a look at Haghipour et al., 2012, EPSL, where they invesfigated GPS data versus\nfolded terraces.\nLine 71: out of place\nLine 160: some English issue here\nLine 201: I could not enfirely follow why Ainscoe et al. argued that co-seismic slip events are not\nsufficient based on the sentence before\nL231: There are many mechanical models that show synchronous duplex thrusfing though. Maybe worth\nmenfioning (e.g. Dal Zilio et al., 2020; Tectonics)"}, "author_response": "Response to Reviewers\nReviewer #1: [Verbatim text of Reviewer 1's report included in the rebuttal] Thank you for your positive evaluation and recommendation of publishing this manuscript in Nature Communications. We have carefully addressed all comments and suggestions, and thank you again for your thorough revision. [Detailed point-by-point responses to Reviewer 1] Reviewer #2: [Verbatim text of Reviewer 2's report included in the rebuttal] We greatly appreciate your positive comments on the importance of the scientific questions we are addressing here, the robustness of our deformation models and associated results, as well as realistic explanations of the deformation mechanisms. [Detailed point-by-point responses to Reviewer 2, including Figures R1-R6] Reviewer #3: [Verbatim text of Reviewer 3's report included in the rebuttal] Thank you very much for your overall positive, detailed and very helpful comments and edits, and we have carefully considered them all and address them below. [Detailed point-by-point responses to Reviewer 3]"}, {"round": 2, "reviewer_comments": {"reviewer_3": "Secound round of review of the manuscript with the fitle \"Reconciling pafterns of long-term topographic growth with coseismic uplift by synchronous duplex thrusfing\" submifted to Nature Communicafions.\nI checked through the responses and implementafions of my previous comments and I am now in favor of accepfing the manuscript.\nBest wishes"}, "author_response": "Second round of review of the manuscript with the title \"Reconciling patterns of long-term topographic growth with coseismic uplift by synchronous duplex thrusting\" submitted to Nature Communications.\nI checked through the responses and implementations of my previous comments and I am now in favor of accepting the manuscript.\nBest wishes\nWe really appreciate your time and effort in reviewing our manuscript and are very glad to hear that you are accepting the manuscript. Your feedback has greatly improved the quality of our manuscript."}]

Decision letter