INTRODUCTION

A large number of studies are devoted to the neotectonics and stratigraphy of Cenozoic deposits in the Altai Mountains (Yakovlev, 1939; Obruchev, 1948; Devyatkin, 1965; etc.). At the end of the Cretaceous and Paleogene in the Altai Mountains, the relief was peneplanated with the formation of a thick weathering crust (Dobretsov et al., 2016). The studies (Bogachkin and Rakovets, 1971; Bogachkin, 1981) showed that wide shallow troughs began to form in the inner regions of the peneplanated uplift at this time. According to other data, these structures formed only at the end of the Paleogene, when the emerging general arched uplift differentiated into areas of local uplifts and troughs (Devyatkin, 1965; Vetrov, 2016). The most contrasting movements that formed the modern relief of the Altai Mountains occurred at the end of the Neogene–Anthropogene (Dobretsov et al., 1995). This same time is associated with the beginning of the neotectonic stage in this territory (Novikov, 2004; Fedak et al., 2011). In (Zolnikov and Mistryukov, 2008), based on a detailed study of Quaternary deposits of southeastern Altai, it was stated said that the neotectonics revived at the turn of the Late Würmian (the last Würmian glaciation is dated from 30 to 11.7 ka) and the Holocene. This is evidenced by a series of giant rockfall–landslides and sandy deposits of shallow local dammed lakes in the Chuya and Katun rivers valleys.

The aim of our research was to reconstruct the natural tectonic stresses using various tectonophysical methods. To establish the regional stress field, the neotectonic faults expressed in the modern relief were identified. A feature of this work is application of the structural–geomorphological method in the conditions of the mountain-folded structure of the Altai Mountains, which was neotectonically activated. The conducted field studies made it possible to confirm the results of reconstructing the neotectonic stresses.

GEOLOGY OF THE STUDY AREA

The study area is located in the southeastern Altai Mountains and includes the Chuya–Kurai depression and its surrounding structures (Fig. 1). The main orographic elements of this territory are ridges and basins. The southern part hosts the largest intramontane basin of Altai, the Chuya depression, and to the northwest, the Kurai depression. They are almost entirely confined to the Chuya River valley. Within the southern part of the Chuya depression are the estuarine parts of the left tributaries of its valley: the Elangash, Kokozek, and Tarhata rivers.

Fig. 1.
figure 1

Orographic sketch map of southeastern Altai Mountains. 1, Rivers; 2, freshwater lakes; 3, border of administrative-territorial units; 4, border of Russian Federation, 5, field observation points.

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From the north, the Chui and Kurai depressions are framed by the Kurai Ridge with elevations up to 3200–3400 m, extending WNW and transitioning in the west into the Aigulak Ridge with elevations up to 2600 m (within the area under consideration). From the south, these basins are bounded by the North Chuya (with elevations up to 3700–4000 m) and South Chuya (the relief reaches ~3900 m) ridges.

In the north of the region, from west to east, there are the Sumulta Ridge (elevations up to 2700 m), the Ulagan Plateau (average elevation 2100 m), the Chulymshan Highlands (elevations 3000–3100 m) and the Shapshal Ridge (elevations of about 3000 m), separated by the Bashkaus and Chulymshan river valleys. All of these structures have northwestern and NNWern orientations. Between the Shapshal and Chikhachev ridges is the Dzhulukulskaya depression.

In general, the ridges have peaks with a typical alpine appearance: peaked, covered with permanent snow and glaciers with steep slopes cut through by mountain rivers. The depressions are filled with Upper Neopleistocene lacustrine–glacial and glacial–lacustrine sediments, in some cases underlain mainly by biogenic limestone (shell rock) of the Neogene. On the periphery, landslide processes are widespread and a relatively dense ravine network is observed. The depressions are generally characterized by a scarplike glacial–accumulative hilly-ridge, and flat relief.

Tectonically, the study area belongs to the southwestern part of the Altai–Salair–Mongolia fold zone (Tektonicheskaya…, 2008) and is characterized by a complex fold-block structure (Fig. 2). In this territory, structural-formation zones (SFZ) of the Early Paleozoic folded basement are distinguished, as well as their overlying, less deformed or almost completely undeformed troughs, depressions and grabens, which consist of Ordovician, Devonian, Carboniferous, Mesozoic, and Cenozoic sedimentary and volcanosedimentary deposits (Fedak et al., 2011). Figure 2 shows the overlying Cenozoic Chuya, Kurai, and Dzhulukul depressions. The first two depressions are separated by the Chagan–Uzun (Sukor) massif, or block, composed of Precambrian and Paleozoic rocks.

Fig. 2.
figure 2

Tectonic scheme of southeastern Altai Mountains, based on materials (Fedak et al., 2011). 1–4, Fold systems: 1, Altai–Salair; 2, Altai–Kuznetsk–Sayan; 3, Altai–Sayan–Tuva; 4, Mongolia-Altai; 5–6, major faults: 5, faults with complex or unidentified kinematics; 6, strike-slip faults (dextral and sinistral); 7–11, minor faults: 7, faults with complex or unidentified kinematics; 8, strike-slip faults (dextral and sinistral); 9, thrusts; 10, extension zones; 11, boundaries of allochthons; 12, overlying Cenozoic depressions: (a) Chuya, (b) Kurai, (c) Julukol. Numerals on map show structural and facies zones: 1, Anui–Chuya; 2, Biysk–Katun (Kadra–Baratal fragment); 3, Uymen–Lebed; 3a, Balkhash fragment; 4, Telets–Chulyshman; 5, Abakan–Shapshal; 6, Syuthol; 7, Khemchik–Sistighem; 8, Shui; 9; Kobda–Monguntaiga; 10, Ulgiy-Yustydskaya; 11, Kholzun–Chuya.

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Studies many researchers of Altai stress the importance of Paleozoic fault tectonics, the position of which played a significant role in the formation of both Mesozoic and Cenozoic structures in the region. The boundaries for the structures shown in Fig. 2 are faults with different kinematics (strike-slips, thrusts, extension zones, etc.) and occurrence times (Early, Middle, Late Paleozoic, Mesozoic, and Cenozoic). Most researchers believe that neotectonic faults inherit the disjunctive structures that occurred and developed in the Paleozoic, but their kinematics changed. For example, in (Dobretsov et al., 1995, 2004), it is shown that the Mesozoic faults manifested to the south of the Chuya–Kurai depression were inherited from the Paleozoic and accompanied the formation of the Pre-Altai belt of Jurassic depressions. Below, the largest gaps shown in Fig. 2 are described.

Kadra fault—a system of steeply dipping sinistral strike-slip and transpressional faults with a NNW strike and horizontal offsets of up to several tens of kilometers. To the southeast, this fault zone transitions into the Kurai fault, which, in the modern tectonic structure, is a dextral strike-slip fault with a WNW strike and significant horizontal offsets; east of the Chagan–Uzun block, it acquires a sublatitudinal strike and sinistral strike-slip kinematics.

Charysh–Terekta fault—separates the Ulgii–Yustydsk and Kholzun–Chuya SFZ and is a system of steeply dipping dextral faults with a sublatitudinal–NW strike.

Shapshal fault system—NW-trending, separates the Telets–Chulyshman and Abakan–Shapshal SFZ, being a dextral transpressional fault with a steep (70°–90°) NE-dipping fault plane.

In general, the largest faults in this area have a northwestern strike and in the Paleozoic–Mesozoic were sinistral strike-slips (transpressional faults) in a sublatitudinal subhorizontal compression setting (Dobretsov et al., 1995, 2016; Novikov, 2001, 2004; Buslov, 2011).

METHODS FOR STUDYING NEOTECTONIC STRESSES

The neotectonic stress state in the study area was identified by the cataclastic fault analysis method (Rebetsky, 2007; Rebetsky et al., 2017) and the structural-geomorphological shear displacement analysis method (Sim, 1991; Rebetsky et al., 2017). To collect structural and geological data, in 2018 and 2022, tectonophysical field studies were carried out in the Chuya River valley from Chibit in the west to Kokorya in the east. During field studies in the framing structures of the Chuya–Kurai depression, slickensides and other geological indicators of deformations were measured. Tectonic stresses were reconstructed by the cataclastic fault analysis method (Rebetsky, 2007; Rebetsky et al., 2017). An advantage of this method is the ability to determine the quantitative characteristics of the stress-strain state at the observation point: the position of the principal stress axes and LodeNadai coefficient. The STRESSgeol computer program, developed at the Laboratory of Tectonophysics of IPE RAS, divides shear fractures into homogeneous samplings that determine the time phases of quasi-homogeneous deformation of the macrovolume to achieve the maximum total dissipation energy with a minimum number of separated phases.

The structural-geomorphological (SG) method for reconstructing tectonic shear stresses (Sim, 1991, 2000; Rebetsky et al., 2017, 2019) uses data on the regular orientation of en echelon faults in the zone of influence of dynamic shear (Fig. 3), which were summarized in (Gzovsky, 1975). We call such a scheme the Gzovsky chart, which we used to reconstruct neotectonic stresses. The method makes it possible to determine the orientations of the compression and tension axes in the horizontal plane and direction of shear movement along the fault and evaluate the geodynamic conditions of fault formation in the sedimentary cover as transpression (transpression) or extension (transtension).

Fig. 3.
figure 3

Paragenesis of en echelon fractures in shear zone (Gzovsky, 1975) or Gzovsky diagram. (a–d) Variants of stress state at cleavage angles: (a) close to 45°, (b) less than 45°, (c) in transtensional conditions, (d) in transpressional conditions; 1, fault; 2, tension fracture; 3, 4, shearing fracture on dextral (3) and sinistral (4) shear component; 5, 6, orientation of tensile (5) and compression axes (6) in horizontal plane; 7, 8, orientation of transtensional (7) and transpressional axes (8) in horizontal plane.

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The factual material for the SG method was relief interpretation data: lineaments (possible faults) and megafractures, which are interpreted as en echelon faults in the shear zone. As well, the age of the reconstructed stress states is taken as neotectonic and present-day, since the indicators of deformation structures were identified from the results of interpreting the modern relief.

When interpreting the relief, it is possible to distinguish shearing and tearing megafractures. Shearing fractures in most cases correspond to rectilinear landforms, while tearing fractures correspond to streams that strongly meander within a megafracture, elongated lakes in river channels, and rectilinear boundaries of swamps and lakes. Their orientations should correspond to two systems of en echelon adjacent shearing fractures and tearing fractures. In this case, the compression axes should be oriented in a certain way with respect to the lineament—at an angle of 30° with transtension, 45° with a triaxial stress state, and 60° with transpression (Fig. 3). The mutual orientations of en echelon faults in the zone of influence of dynamic shear were generalized in (Gzovsky, 1975).

If the orientation of megafractures identified near the lineament, both between themselves and with respect to the fault, corresponds to one of the orientations of the en echelon faults in the shear zone (see Fig. 3), then it is assumed that the lineament and megafractures have a tectonic nature. As well, the orientations of the axes of compression and extension in the horizontal plane and sign of shear displacement (dextral or sinistral) are determined, and the geodynamic conditions for activation of a basement or sedimentary-cover fault (transpression or extension) is also established. It is assumed that one of the horizontal axes can be the axis of the intermediate principal normal stress. In the case when megafractures testify to am extensional setting, the intermediate and compression axes can be approximately equal, and in the case of reconstruction of the compression setting, accordingly, the tensile and intermediate axes are approximately equal. This because, during fault formation, the fault plane in the basement and/or sedimentary cover is traced through young deposits influenced by tectonic stresses. At the same time, the master fault plane may not have yet formed on the exposed surface, but the en echelon faults already form a zone of increased fracturing, which is interpreted above basement faults, while in the sedimentary cover at some intermediate fault activation stage, it can be expressed as a flexurelike bend or zone of increased fracturing.

Manifestation on the exposed surface of shear in the basement at the stage with no master plane in the sedimentary cover is established according to mathematical (Rebetsky, 1987) and physical (Mikhailova, 2006) shear modeling. As a result of these studies, it was revealed that small faults on the exposed surface should in physical modeling be oriented in the same way as fractures in the clay layer at the base of the sedimentary cover (Mikhailova, 2006).

The use of the SG method within the southeastern Altai Mountains is the result of materials of a number of researchers (Novikov, 2001, 2004; Buslov, 2011; Fedak et al., 2011; Buslov et al., 2013; Dobretsov et al., 2016; Marinin et al., 2019), which identify strike-slips that are active at the neotectonic and present-day stages of tectonic development in this area. To reconstruct neotectonic stresses by the SG method, we used data from topographic maps at a scale of 1:1 000 000 and 1:200 000, as well as geological, tectonic, and other maps and diagrams.

NEOTECTONIC STRESSES BASED ON RECONSTRUCTION OF TECTONIC STRESSES BY TECTONOPHYSICAL FIELD METHODS

The data acquired during field studies demonstrated the possibility of determining the kinematics of minor faults and reconstructing the tectonic stress parameters. In total, using the cataclastic fault analysis method, it was possible to determine the parameters of the stress-strain state for 35 local stress states (Fig. 4).

Fig. 4.
figure 4

Sketch map of observation points with orientation of reconstructed position of maximum compression axis or intermediate axis (with subvertical position of compression axis) of distribution, as well as type of stress state: 1, horizontal tension; 2, horizontal tension in combination with shear; 3, horizontal shear; 4, horizontal compression in combination with shear; 5, horizontal compression; 6, direction of dip of maximum compression axis; 7, direction of dip of intermediate principal stress axis. Insets: (a) distribution of stress state types; (b) digital elevation model.

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The directions of the principal stress axes obtained from the reconstruction are characterized by a rather large variability. In the above diagram (Fig. 5), where all the corresponding axes have been removed, it can be seen that the axes have different azimuths and dip angles, while the density maxima in general reveal the most characteristic trends. The axis of maximum compression (σ3) is characterized by submeridional (NW) and NE orientations; near the Chuya depression, a northwestern orientation of maximum compression is manifested. Axes σ1 (tension) have a sublatitudinal west–northwest orientation. The intermediate axis for most local stress states is frequently subvertical.

Fig. 5.
figure 5

Orientation of principal stress axes of local stress tensors based on results of inversion using slickenside data sets. Stereoplots (upper hemisphere) show outputs of principal stress axes and equal distribution density isolines (color fill). (a–c) Axes σ1, σ2, σ3 of minimum (deviatory tension), intermediate, and maximum compressive stress.

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In contrast to the results of reconstruction from seismological data (Rebetsky et al., 2013), according to field tectonophysical observations, horizontal extension settings are quite rare (Fig. 6 shows an example of a horizontal extension setting in the southwestern part of the Chuya depression). Among the types of stress state identified by us, a horizontal shear setting prevails (15 determinations). Figure 7 shows an example of a horizontal shear setting at observation point no. 18 600 on the southwestern wall of the Chuya depression. There are also of horizontal extension (eight determinations) and horizontal compression settings (six determinations). The predominant horizontal shear settings, which, together with transitional types (horizontal transpression and transtension) make up more than half the reconstructed local stress states, permits use of the SG method to reconstruct neotectonic stresses in the studied region.

Fig. 6.
figure 6

Stereoplots (upper hemisphere) showing poles of planes of tectonic faults of various types (a) and position of principal stress axes determined by cataclastic analysis method of geological data on slip faults (b) at site no. 18594 (Chuya River valley near village Chagan–Uzun): 1–8, poles of tectonic faults with a predominant type of displacement: 1, reverse faults and thrusts, 2, normal faults, 3, dextral strike-slip faults, 4, sinistral strike-slip faults, 5, dip-slip faults, 6, strike slip-faults, 7, tension gashes, 8, veins; 9, shatter zones; 10, joints; 11–12, elements of bedding stratification: 11, normal; 12, overthrusted; 13–15, principal stress axes: 13, minimum, 14, intermediate, 15, maximum. Dashes on edges of 1–4 indicate additional component of relative movement on slickensides (sinistral or dextral strike-slip faults, reverse or normal faults).

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Fig. 7.
figure 7

Stereoplots (upper hemisphere) showing poles of planes of tectonic faults of various types (a) and position of principal stress axes determined by cataclastic analysis method of geological data on slip faults (b) at site no. 18600 (Chuya River valley near village of Chagan–Uzun). Symbols are same as in Fig. 6.

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RESULTS OF RECONSTRUCTING NEOTECTONIC STRESSES BY THE SG METHOD

As a result of interpretation of the topographic map (scale 1 : 1 000 000), lineaments were identified—possible neotectonic faults. When analyzing the level of their expression in the relief and comparing them with earlier identified faults (Novikov, 2001; Dobretsov et al., 2004, 2016; Fedak et al., 2011), it was possible to identify four faults of the first rank: (1) the Kurai fault, which changes strike from sublatitudinal in its eastern part to west–northwestern in the central part; (2) the NE part of the Chagan–Uzun fault, which, in our interpretation, merges with the western part of the (3) Charysh–Terekta fault and is distinguished as a single fault of the first rank with an east–NE strike; (4) in the north of the study area, another ENE-trending fault (Shavla fault) was identified, clearly manifested in the Shavla River valley and continuing WSW to the lower reaches of the Chibitka River.

We attributed other lineament-faults (less extended and less expressed in the relief) to the category of faults of the second rank only if megafractures were mapped near them (small rectilinear landforms—possible en echelon faults in the zones of influence of dynamic shear). Using the SG method, the directions of shear displacements along faults were determined and the neotectonic stresses of the Chuya–Kurai depression, as well as its framing structures, were reconstructed. All determinations of the orientation of the compression axes, which correspond to two (in some cases, one) systems of R- and R′ shearing fractures, as well as megafractures parallel to the compression axis and normal to the tensile axis, were plotted in the areas of the faults near which they were determined (Fig. 8).

Fig. 8.
figure 8

Scheme of neotectonic stresses and faults of Southeastern Altai (SG method). 1, Faults of first rank: dextral and sinistral strike-slip faults; 2–3, faults of second rank: 2, dextral and sinistral strike-slip faults; 3, lineaments; 4, inferred faults; 5, orientation of compression axis; 6, orientation of transpression axis; 7, rivers, 8, border of administrative-territorial units; 9, detailed research area (Fig. 10). Roman numerals on map (I–IV) are neotectonic faults: Ia, eastern branch of Kurai fault, Ib, western branch of Kurai fault; II, Chagan–Uzunsky; III, Charysh–Terekta; IV, Shavla.

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Analysis of the kinematic types of displacements reconstructed by the SG method along strike-slip faults showed that the NW- and WNW-trending faults of both first and second ranks are dextral strike-slips, while the NE-trending faults are sinistral strike-slips. Meanwhile, along the Kurai fault, in its eastern latitudinal part, sinistral displacement was reconstructed, and in the western part, dextral displacement with a WNW orientation. In this case, a positive structure should form on the northern flank of the fault in the area of change of shear displacements as a result of squeezing out of material along blocks of rocks moving towards it.

This assumption is indirectly confirmed by the highest elevations of peaks in this part of the ridge: 3335, 3412, and 3256 m (see Fig. 8), as well as maximum dissection of the western and southern slopes of the summit with an elevation of 3412 m. Approximately along the axis of this squeezing structure, a second-order rectilinear meridional fault appeared, developed by the Ildumgen River valley. The ideal rectilinearity of the Ildumgen River bed may speak in favor of the shear nature of this fault in the local compression zone.

The reconstructed compression axes (by definition, they are perpendicular to the orientation of the tension axes in the horizontal plane, which to avoid cluttering the diagram are not shown) are neotectonic, since they were determined from analysis of rectilinear landforms that arose at the neotectonic stage, as indicated earlier. The rose diagram in Fig. 9 shows that the orientation of the compression axis in this area changes from meridional to NNE.

Fig. 9.
figure 9

Orientation of reconstructed compression axes (SG method) within southeastern Altai Mountains.

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For the Chagan–Uzun block, neotectonic stresses were additionally reconstructed using a topographic map on a larger scale (1:200 000), since on a small-scale map (scale 1:1 000 000) it was not possible to identify enough megafractures to reconstruct the orientation of the principal normal stress axes. Figure 10 shows results of studying neotectonic stresses of the Chagan–Uzun: from faults of the second rank, which complicate the structure of this block, the orientations of the compression axes were reconstructed restored, which are consistent with the orientation of the compression axes, which are generally characteristic of neotectonic stresses of the entire Chuya–Kurai depression. It should be noted that for the complex Kurai fault, along its SSW branch, the SG method determined contradictory orientations of the shear component: in the eastern, sublatitudinal part, it was activated as a sinistral strike-slip, and in the western, as dextral.

Fig. 10.
figure 10

Scheme of neotectonic stress of Chagan–Uzun block (SG method): 1, faults of first rank (dextral and sinistral strike-slip faults); 2–3, faults of second rank: 2, dextral and sinistral strike-slip faults; 3, lineaments; 4, orientation of compression axis; 5, orientation of transpression axis; 6, rivers.

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The orientation of the compression axes determined by us is consistent with the opinion of predecessors on the existence of NE and meridional compression at the neotectonic stage in the study area, as well as with modern stresses analyzed by earthquake focal mechanisms (Rebetsky et al., 2013). For a number of faults, compression settings were determined in which neotectonic faults occur. This also agrees with the view that the region was deformed in a compression setting (Delvaux et al., 1995, 2004; Novikov, 2004). In was impossible to determine an extensional setting from any of the faults.

A change in the regional geodynamic setting should have affected the orientation and kinematics of the faults, so we constructed rose diagrams of the strikes of ancient (Paleozoic–Mesozoic) and neotectonic faults in the study area (Fig. 11). The rose diagrams constructed for a number of faults (Fig. 11a) shows that the prevailing orientations for the ancient faults are NE (60°) and NNW (350°); there are also NW (310°–320°) and sublatitudinal (280°) orientations. For the neotectonic faults, a NW (290° and 310°) orientation dominates; ENE (60°–80°) and NE (30°) orientations are also noted. According to the rose diagrams constructed from the sum of the lengths of similar faults (Fig. 11b), it is significant that the most extended ancient faults have NE (60°), NW (300°, 330°), and sublatitudinal (280°) orientations, while the neotectonic faults, sublatitudinal (280°–290° and 80°) and NW (310°–320°).

Fig. 11.
figure 11

Rose diagrams of orientation of ancient faults (1) based on materials (Fedak et al., 2011) and neotectonic faults (2) identified by SG method. (a) Number of disjunctive elements of certain direction (with step of 10°), (b) length (sum of lengths) with similar step.

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Comparison of the rose diagrams of the strike of ancient and neotectonic faults showed that not all faults of earlier stages were activated at the neotectonic stage: faults with sublatitudinal (280°–290°) and NW (310°–320°) strikes were activated the most; NE-trending neotectonic faults (60°–80°), less so.

When analyzing rose diagrams, there are several factors to consider: (1) the formation of ancient faults was multistage; (2) during the Pre-Cenozoic stage of development, the fault zones underwent significant spatial displacements due to the tectonic plate movements, as well as within-plate movements; (3) at the neotectonic stage, activation of “ancient” faults in the modern relief is manifested in a rather fragmentary manner.

Our analysis shows that at the neotectonic stage, some neotectonic faults inherited the development of ancient faults. Thus, the most long-lived at all stages of the regional tectonic development are extended faults with a sublatitudinal and WNW strike, confirmed by geological data on faulting of the Early–Middle Devonian metamorphic complex in the axial part of the Kurai Ridge by later strike-slip zones of the Early Carboniferous (Buslov et al., 2013; Nevedrova et al., 2014). In all likelihood, these strike-slip movements were also activated at the neotectonic stage of the region’s development.

CONCLUSIONS

(1) Neotectonic faults have been identified, largely inherited from faults of the ancient Paleozoic–Mesozoic system, which underwent complex activation at different stages of their development. At the neotectonic stage, these faults were activated along large faults, but their spatial positions were restructured at the neotectonic stage. Individual parts of Pre-Cenozoic faults are combined, and a neotectonic fault network with rejuvenated “generalized” strikes formed.

(2) Using various tectonophysical methods, we have reconstructed tectonic stresses in the Chuya–Kurai depression in the Altai Mountains. The position of activated faults that experienced significant displacements in the Paleozoic–Mesozoic has been refined; they formed in a geodynamic compression setting with subhorizontal and predominantly sublatitudinal orientation.

(3) Our tectonophysical studies established that at the neotectonic stage, the faults were deformed under active NNE horizontal compression, while the NNW and submeridional directions of compression were of subordinate importance. This confirms the conclusion of predecessors on the direction of acting stresses, obtained from seismological, geological, and geomorphological data.

(4) Ancient (Paleozoic–Mesozoic) faults have been distinguished, which were activated as a whole or in separate parts when the orientation of the axes of the principal normal stresses changed at the neotectonic stage.

(5) Comparison of rose diagrams of the strike of ancient and neotectonic faults showed that not all ancient disjunctive structures were activated at the neotectonic stage. The neotectonic faults with sublatitudinal (280°–290°) and NW (310°–320°) strikes were the most activated.

(6) Numerous small neotectonic faults were shown, which were rejuvenated in a neotectonic geodynamic setting as possible extensions in a stress field with a NNE orientation of maximum compression. The proposed scheme of neotectonic stresses in the Chuya–Kurai depression is important for analyzing present-day seismicity.