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. 2022 Dec 5;8(12):e12038. doi: 10.1016/j.heliyon.2022.e12038

Quartz c-axis fabric characterization of the strike-slip ductile deformation within the Three Pagodas shear zone, western Thailand

Sittiporn Kongsukho a, Pitsanupong Kanjanapayont a,b,∗
PMCID: PMC9732306  PMID: 36506361

Abstract

The Three Pagodas shear zone is associated with mainland Southeast Asia deformations. The evolution of the shear zone is divided into deformation phases D1a, D1b, and D2. The first phase (D1a) involved ductile sinistral shearing associated with metamorphism. Foliations are well developed in a NW–SE with variable dips from east to west. Stretching lineations show NW–SE trending strike and flatly plunge to the south. Based on deformation patterns exhibited by outcrop and microscopic analysis, D1a shows NW–SE trending of ductile sinistral shearing. Additionally, the quantitative analysis of mylonitic quartzite exhibits an oblique angle of quartz grain shape fabric and quartz c-axis fabric asymmetry. Sinistral simple shear was confirmed by kinematic vorticity (Wk). The spatial distribution of the kinematic velocity number (Wk) of D1a shows a range between 0.93 and 0.99 at the central and western parts of the shear zone, which is higher than the 0.82–0.85 range for the eastern part of the shear zone. The strain variation within the Three Pagodas shear zone derived from the kinematic vorticity number (Wk) shows that the central and the western parts have been deformed under simple shear more than the eastern part. D1b is represented by the exhumation of high-grade metamorphic complex from sinistral transpression. The last stage (D2) involved the inversion of this strike-slip system, which is represented by dextral strike-slip faults.

Keywords: Quartz c-axis, Kinematic vorticity, Sinistral, Three Pagodas shear zone, Thailand

Quartz c-axis; Kinematic vorticity; Sinistral; Three Pagodas shear zone; Thailand.

1. Introduction

The complex geologic structures and tectonics in Southeast Asia were influenced by the collision between the Indian and Eurasian plates in the Cenozoic (Tapponnier et al., 1982, 1986; Huchon et al., 1994; Lacassin et al., 1993, 1997; Morley, 2002), which took place at ∼50–45 Ma (Molnar and Tapponnier, 1975). It is estimated that India is moving northward at a rate of 45 mm/year and has penetrated at least 2000 km into Asia (Molnar and Tapponnier, 1975). The increased subduction obliquity of the Indian plate to the west of SE Asia affected a clockwise rotation in the SE Asia region (Tapponnier et al., 1982). This collision created complex structures along the Himalayan–Tibetan Plateau and facilitated motion along strike-slip faults in eastern Tibet and SE Asia (Chung et al., 1997, 1998, 2005; Lacassin et al., 1993, 1997; Lin et al., 2012). Based on the model of extrusion tectonic, the strike-slip systems in SE Asia (e.g. the Jiale and Altyn Tagh faults in South China, the Ailao Shan–Red River fault in South China and Vietnam, the Sagaing fault in Myanmar, the Mae Ping and Three Pagodas faults in Thailand) exhibit sinistral shearing (Tapponnier et al., 1986, 1990; Leloup et al., 1995; Lacassin et al., 1993, 1997; Rhodes et al., 2005), that began at about 40–50 Ma (Lacassin et al., 1997; Upton, 1999; Nantasin et al., 2012; Palin et al., 2013; Österle et al., 2019; Simpson et al., 2021). The focal mechanisms and geomorphology demonstrate the inversion of the strike-slip faults (Tapponnier et al., 1986; Lacassin et al., 1997; Charusiri et al., 2002; Morley, 2002; Rhodes et al., 2005) at about 30–37 Ma (Lacassin et al., 1997; Upton, 1999; Morley et al., 2007; Simpson et al., 2021). This reverse motion was possibly caused by the stress field changing in the SE Asia (Huchon et al., 1994; Richter and Fuller, 1996).

The Three Pagodas shear zone is one of the major strike-slip zones in Thailand (Kanjanapayont, 2015). It is characterised by a NW–SE trending mylonite zone ∼50 km wide at Thabsila village and extending southeastward for ∼25–30 km (Bunopas, 1981; Kanjanapayont, 2015). This shear zone lies parallel to the south of the Mae Ping shear zone in western Thailand, and possibly shares an origin with the Sagaing fault in Myanmar (Tapponnier et al., 1986; Lacassin et al., 1997; Morley, 2002). This strike-slip zone may extend to the Gulf of Thailand (Tapponnier et al., 1986; Polachan et al., 1991; Lacassin et al., 1993, 1997) and Hua Hin-Pranburi fault zone (Tulyatid, 1991), or pass through Central Thailand and connect to the Klaeng fault in eastern Thailand (Morley, 2002; Ridd, 2009). In SE Asia, the strike-slip models suggest that the NW–SE strike-slip zones including the Three Pagoda shear zone were started by sinistral shearing in the beginning and inverted to dextral movement (Huchon et al., 1994; Lacassin et al., 1997; Rhodes et al., 2005). In the Three Pagodas shear zone, the mylonites have been attributed to the sheared high-grade metamorphic rock (Nantasin et al., 2012; Kanjanapayont et al., 2018; Salypongse et al., 2020). Two-dimensional strain ratios (Rs) in the XZ-plane of 1.60–1.97 for the simple shear component were exhibited by quartz mylonites in the shear zone (Kanjanapayont et al., 2018). The development of a Cenozoic pull-apart basin was presented in the later stage (Rhodes et al., 2005).

Many microstructure studies of the mylonites have demonstrated the geometry and mechanisms of micro-deformation in the shear zone and have successfully used quantitative kinematic analysis to reveal the deformation history of the shear zone (Law et al., 2004; Kanjanapayont et al., 2012a; Faghih and Soleimani, 2015; Spanos et al., 2015; Xypolias et al., 2018). This study presents the quantitative kinematic analysis of the mylonitic rocks from the Three Pagodas shear zone. Focus in placed on oblique grain shape fabric and crystallographic preferred orientation fabric. The results reveal the details of the strike-slip ductile behavior and kinematic history of the Three Pagodas shear zone. The kinematic history of Three Pagodas shear zone may hold valuable information as it is related to the Indian-Eurasian collision from Eocene–recent.

2. Geological setting

The Three Pagoda shear zone and adjacent areas comprise a succession of the sedimentary rocks in Paleozoic derived from Cambrian to Permian, Cenozoic sediments, and granitic rocks in the Triassic (Department of Mineral Resources, 2008). The ‘Thabsila Gneiss’ or ‘Thabsila metamorphic complex’ was mapped as Precambrian rocks within the Three Pagoda shear zone (Department of Mineral Resources, 2008; Salypongse et al., 2020). This high–grade metamorphic complex is located about 40 km northwestern from the Kanchanaburi province, western Thailand. The Thabsila metamorphic complex was previously classified into units A, B, C and D (Nantasin et al., 2012). First, unit A is marble interbedded with mica schist, fine grained biotite gneiss along with quartzite formed under P-T condition of 550 °C–630 °C and 5.5–6.5 kbar. Unit B comprises mylonite and mylonitic gneiss showing an augen structure with highly deformed texture. Unit C comprises calc–silicate interbedded with silicate bands, which are segregation layers of marble and diopside. Unit D is a variety of components, including biotite gneiss, orthogneiss, sillimanite gneiss and mylonite. The Thabsila metamorphic complex formed medium amphibolite facies in unit A, whereas other three units represent the upper amphibolite facies. Recent study classified the Thabsila metamorphic complex into four units as Thabsila zones A, B, C and D (Salypongse et al., 2020). In the Salypongse study, Zone A comprises migmatite, gneiss and cala–silicate. Migmatite is dark grey to black, coarse grained, with partially melted leucocratic veins. Gneiss is coarse to medium grained, with interbedded light and dark bands. Calc–silicate is characterised by brownish green, coarse grained, foliated layers between silicate and carbonate layers. Zone B is presented by schist interbedded with quartz mica schist, fine grained paragneiss and calc–silicate. Schist and paragneiss show thin layers, schistosity foliation and aluminosilicate minerals, such as sillimanite or fibrolite, especially in higher zones. Quartz mica schist to quartz schist show micaceous-rich schistosity in the main assemblage. Zone C is mainly meta-limestone, quartzite, phyllite and schist. Quartzite is medium grained and well sorted, and most quartz grains display foliated texture. Phyllite to schist is grey phyllite, schist, kyanite and andalusite porphyroblasts. Zone D shows fine grained greenish grey slate. In the upper part of the Thabsila metamorphic complex, meta-limestone and meta-sandstone are exposed.

The previous studies suggested that the age of the Thabsila metamorphic complex is Precambrian based on stratigraphic correlations, high-grade metamorphism and high deformation (Bunopas, 1981). Recently, U–Pb zircon ages of some inherited zircon cores yielded between ∼400 and ∼1,450 Ma, whereas partly cores were an age of ∼200 Ma (Nantasin et al., 2012). Rims of zircon yielded average values between ∼51 and 57 Ma and have been interpreted as the peak metamorphism (Nantasin et al., 2012). These ages can be compared to the U–Pb calcite age of ∼48 Ma (Simpson et al., 2021). K–Ar and Ar–Ar biotite ages of 33–36 Ma were attributed to the ductile sinistral sharing in the Oligocene (Bunopas, 1981; Lacassin et al., 1997), which conformed to the Rb–Sr isochron biotite ages of ∼32–36 Ma (Nantasin et al., 2012) and ∼39–32 Ma from apatite fission trace (AFT) from granitic rock outside the shear zone (Upton, 1999). U–Pb calcite age of ∼23 ± 1 Ma corresponded with the beginning of reversal of movement from ductile sinistral to brittle dextral (Simpson et al., 2021) and conformed to the AFT from granitic rock outside the shear zone at ∼24–19 Ma (Upton, 1999).

Herein, the mylonites in the Three Pagodas shear zone comprise six units of high- and low-grade metamorphic rocks (Kongsukko and Kanjanapayont, 2022) (Figure 1). They are migmatitic gneiss, augen gneiss, marble, schist, quartzite and calc–silicate (Figures 2A–G, Figure 3A–F).

Figure 1.

Figure 1

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Geological map of the Three Pagodas shear zone and adjacent area (modified after Department of Mineral Resources, 2008).

Figure 2.

Figure 2

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Lithologic variations of the metamorphic rocks within the Three Pagodas shear zone; augen gneiss with S–C fabric (A), marble (B), migmatitic gneiss showing leucosome and mesosome (C), schist with asymmetric grain (D), calc–silicate (E), quartzite showing stretching lineations (F), foliations and stretching lineation (G) and their stereonet plots (H).

Figure 3.

Figure 3

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Photomicrographs of the metamorphic rocks within the Three Pagodas shear zone; dynamic recrystallisation of quartz (A), stretching quartz grains (B), S–C fabric (C), shearing grains of feldspar (D), asymmetric strain shadow (E) and mica fishes within S–C′ fabric (F).

Migmatitic gneiss is exposed at the centre of the metamorphic complex. This unit shows segregated melting of leucosome and mesosome and discontinuous foliation. The mesosome layer consisted of fine to medium grained feldspar, quartz and biotite (Figure 2C). The leucosome layers were extruded into the fractures of the mesosomes layers. The leucosome layers mainly comprised of irregular shape of coarse to very coarse grained quartz and feldspar with grain boundary migration.

Augen gneiss is characterised by augen-shaped of K-feldspar megacrystals with a strong foliation (Figure 2A). The medium to coarse grained and fine grained gneisses are exposed at the eastern and western rims of the shear zone. K-feldspar, quartz and plagioclase can be observed in the medium to coarse grains, whereas biotite, muscovite, and quartz are presented in the fine grains. Porphyroblast of K-feldspar exhibits twinning and myrmekite. Quartz generally presents undulose extinction. S–C and S–C′ shear bands, which indicated sinistral shearing, are well-observed (Figure 3A).

Marble is exposed in both eastern and western parts of the Three Pagodas shear zone, characterised by white to gray color and fine to medium grained, granoblastic and sugary texture (Figure 2B). The mineral inclusions in the marble mainly comprises plagioclase, graphite, muscovite, phlogopite, quartz and diopside. Chlorite and iron oxide can be found as accessory materials. Subhedral calcite is fine to medium grain, which typically exhibits with polygon, granoblastic and mossy textures. Twins slip plans are well developed in the NW direction as same as the orientation of maximum elongated grain. Undolose extinction can be observed in quartz. This marble unit normally shows S–C and S–C′ shear bands (Figure 3C). All kinematic indicators obviously denote sinistral shearing.

Schist in the eastern and western parts vary in colour and composition (Figure 2D). Schistosity trends to NW–SE with NE dipping is clearly observed. This unit is composed of phyllitic schist, mica schist and quartz schist. Phyllitic schist is characterised by a fine grained and deep grey to back colour. Schistosity in a NW–SE direction was defined by the orientation of fine grained mica. The mineral assemblages of this unit are mainly quartz, muscovite and biotite. Fine to very fine grains of quartz generally shows undulose extinction. Minor minerals are chlorite and clay minerals. Quartz mica schist clearly displays schistosity. It shows medium to coarse grained in brown colour. This rock exhibits higher metamorphism than phyllitc schist. Major mineral assemblages are quartz, muscovite biotite, tremolite, and plagioclase. Quartz strongly exhibits dynamic recrystallization with oblique grain shape fabric. All recrystallised grains present sub-grain rotation and grain boundary migration. The NW–SE foliation plane is strongly indicated by muscovite and biotite. Muscovite is more commonly found than biotite. It is usually altered to andalusite and sillimanite. Garnet, zircon, and sericite can be found as accessory materials. Quartz schist has a composition of quartz composition more than 80%. Other compositions are typically similar to mica schist. This rock is yellow to brown and medium to coarse grained with a thickness <1 m. A major mineral assemblage typically comprises quartz, hornblende, mica, and garnet. Irregular quartz grains show undulose extinction and recrystallisation of sheared deformation. Fine grained muscovite presents an average size of 0.2–0.3 mm. Accessory minerals are hornblende and garnet. In this schist unit, domino-type fragmented porphyroclasts and oblique grain shape orientation clearly indicate sinistral movement (Figure 3D–F).

Quartzite is commonly interbedded with schist. This rock exposed all over the shear zone (Figure 2F–G). Quartzite shows fine to medium grained and colourless to yellow. Quartz is medium grained with ribbon and undulose extinction (Figure 3B).

Calc–silicate is widely exposes in the Three Pagodas shear zone. It has a granoblastic and sugary texture. In this unit, a various layers of the green amphibole diopside and white quartz-feldspar layers can be observed as a compaction cleavage (Figure 2E). Major mineral assemblages are quartz, biotite, clinopyroxene, scapolite, plagioclase and calcite. The matrix of quartz and calcite usually displays undulose extinction. In some areas, the exposed calc–silicate is folded with strong gneissic banding. It is characterised by feldspar porphyroblasts. Pyroxene, hornblende, chlorite, epidote and muscovite form the matrix. Sinistral movement in the calc–silicate is clearly indicated by S–C fabric.

The low-grade metamorphic rocks expose along the periphery of the high-grade metamorphic rocks. Exposures of this unit, which is composed of metapelitic and metacarbonate rocks, form as lens shape on the western part.

Metapelitic rock typically comprised slate interbedded with phyllite. Greenschist facies of this unit is indicated by quart, muscovite and biotite. Quartz biotite and chiolite are a major mineral assemblage.

Metacarbonate is characterised by dark blue to grey colour, fine grain, and some lenticular shape of argillaceous layers. The major mineral assemblages comprise quartz, calcite, clay minerals and opaque minerals. The darker bands in this unit mainly comprise silicate, muds and opaque minerals.

3. Structural geology

Detailed structural setting of the area was previously reported by Kongsukko and Kanjanapayont (2022). In the high-grade metamorphic rock, the foliations strike NW–SE with variable dips to both the east and west (Figure 2H). They conform to the NW–SE foliations in the low-grade metamorphic unit. Lineations in the high-grade metamorphic unit, which represented by stretched mineral grains, are more obviously defined than in the low-grade metamorphic unit. The stretched lineations are obviously showed on the foliation planes of augen gneiss, quartzite and schist. They orient with subhorizontal plunging in NW–SE.

Oblique faults with steeply dipping are the major faults in the study area. They have an average NW–SE orientation with high angles around 70°–80° (Figure 4A–C). The fault in this region exhibits a normal movement with dextral shear. The slickensides are generally aligned NW–SE (Figure 4A and B) with subhorizontal plunging to the NW (Figure 4C). Fault breccia in this area is irregularly shaped, fine to coarse grained and poorly sorted.

Figure 4.

Figure 4

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Fault planes showing slickenside (A) and striations (B) of D2, and their stereonet plots (C).

4. Quartz c-axis fabrics

Twelve samples of mylonites from quartzite and schist units in the eastern, central and western parts of the Three Pagodas shear zone were selected for quartz c-axis fabric analysis. Quartz is an important mineral in controlling the rheology of large portions of the Earth’s crust and has the large variety of fabric types found under different deformational and metamorphic conditions (Law, 1990). Universal stage (U-stage) measurements of lattice preferred orientation can be done on a normal microscope, which are inexpensive (Passchier and Trouw, 2005). Herein, the obtained quartz c-axis crystallographic preferred orientation (CPO) fabrics were measured by a Leitz universal stage (U-stage) mounted on a Zeiss optical microscope. The mylonitic samples typically exhibited a strong dynamic recrystallisation and showed well-developed elongated fabric and preferred orientation. They were sectioned along an XZ orthogonal system (Xypolias, 2009, Xypolias et al., 2018). The internal elongated XZ-surface axis of the orthogonal ellipse deformed circle is a maximum value of stretching axis or instantaneous stretching axis (ISA) during deformation (Wallis, 1995; Xypolias, 2009), which is associated with the vorticity vector in progressive subsimple shear. The intersections plane between the oblique foliation surface, referred to as ISA, and mean foliation surface, referred to as main shear zone boundaries (A2) is the angle ξ (Wallis, 1995) However, they are unknown shear zone boundaries (A2) in the natural shear zone. The angle between ISA2 and the flow apophysis A2, ξ angle, can be combined the δ angle and β angle. The δ angle is defined by the intersection plane between the oblique grain shape foliation and the mean foliation, whereas the β angle is presented by the intersection plane between the shear/flow plane and main foliation (Wallis, 1995). In two-dimensional flow, θ = 90°–2(β + δ) (Passchier, 1988). Therefore, the kinematic vorticity number can be rewritten (Wallis, 1995) as follows.

Wk = sin 2(β + δ)

when Wk = 0, the internal rotation is a perfectly coaxial deformation or pure shear, indicating compaction or dilational zones. Conversely, when Wk = 1, non-coaxial progressive deformation or simple shear occurs. The ratio number between 0 and 1 assumes general shear, which is a combination of simple shear and dilation or compaction (Passchier and Trouw, 2005).

Frequency histograms were constructed for the statistical analysis of the orientation data. The angle of oblique (δ), the intersection planes between the oblique quartz grain shape foliation (Sq) and the mylonitic foliation (Sm) were obtained from the measurements of the long axes of 250–350 quartz grains on the XZ plane of 12 mylonite samples (Figure 5A–H). The mean oblique angle has a range between 11° and 25°, and a maximum angle between 25° and 45° (Figure 6A–L).

Figure 5.

Figure 5

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Angle from quartz C-axis analysis showing the oblique grain shape fabric and the main foliation of the samples TB-01 (A), TB-02 (B), TB-03 (C), TB-04 (D), TB-05 (E), TB-06 (F), TB-07 (G) and TB-08 (H).

Figure 6.

Figure 6

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Stereographic plots showing the shear direction in the Three Pagodas shear zone using the mean and maximum apparent angles between the oblique foliation and the Sm of the samples TB-01 (A), TB-02 (B), TB-03 (C), TB-04 (D), TB-05 (E), TB-06 (F), TB-07 (G), TB-08 (H), TB-09 (I), TB-10 (J), TB-11 (K) and TB-12 (L).

The results of CPO of quartz c-axis fabrics have a systematic variation in the evolution of their pattern which lead to increasing strain along the shear zone that are accompanied by changes in crossed girdles and geometry. The mylonitic samples from the Three Pagodas shear zone clearly reveal an asymmetric pattern similar to type I crossed-grained patterns (Lister and Williams, 1979). The characteristics of the crossed-grained pattern display sinistral non-coaxial progressive deformation relative to the slip system in a dominance of rhomb <a> slip (Figure 7A–L).

Figure 7.

Figure 7

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Angle between the perpendicular to the central girdle segment of quartz axis fabric and main foliation from stereographic plots of quartz c-axis analysis of the samples TB-01 (A), TB-02 (B), TB-03 (C), TB-04 (D), TB-05 (E), TB-06 (F), TB-07 (G), TB-08 (H), TB-09 (I), TB-10 (J), TB-11 (K) and TB-12 (L).

5. Kinematic vorticity number (Wk) derived from quartz c-axis fabrics

The kinematic vorticity number results, the comminuted angles between the δ angle and the β angle from oblique grain shape analysis, and the CPO analysis of 12 samples are presented in Table 1. The samples in this area yielded a Wk between 0.82 and 0.99. A summary of the percent of the kinematic vorticity number of the low-grade metamorphic rocks (TB-01, TB-02 and TB-03) displays a general shear regime with 60%–65% simple shear components and 35%–40% pure shear components (Figure 8). The high-grade metamorphic rocks (TB-04, TB-05, TB-06, TB-07, TB-08, TB-09, TB-10, TB-11 and TB-12) show a simple shear dominated regime with simple shear more than 80% and less than 20% of pure shear (Figure 8).

Table 1.

Summarized data from the high-grade metamorphic rocks within the Three Pagodas shear zone.

sample δ β δ + β θ Wk
TB-01 13.06 15.10 28.16 33.69 0.83
TB-02 13.02 14.67 27.69 34.62 0.82
TB-03 11.84 17.30 29.14 31.72 0.85
TB-04 23.89 14.20 38.09 13.82 0.97
TB-05 25.37 16.90 42.27 5.46 0.99
TB-06 21.35 16.30 37.65 14.70 0.97
TB-07 24.08 10.30 34.38 21.24 0.93
TB-08 18.68 19.80 38.48 13.04 0.97
TB-09 24.06 16.30 40.36 9.28 0.99
TB-10 21.22 13.80 35.02 19.96 0.94
TB-11 21.92 12.80 34.72 20.56 0.93
TB-12 21.03 17.30 38.33 13.34 0.97
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Figure 8.

Figure 8

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Diagram plots of the Wk showing the simple shear dominant of the eastern part (red), central part (yellow), and western part (green) within the Three Pagodas shear zone.

6. Discussion

6.1. Deformation history

The deformation stages are D1 and D2. D1 can be divided into substages D1a and D1b based on the details of the kinematic events (Kongsukko and Kanjanapayont, 2022).

6.1.1. D1

6.1.1.1. D1a

The D1a deformation phase involves the ductile sinistral shearing with low- to high-grade of metamorphism at the upper to lower level throughout the Three Pagoda shear zone (Kongsukko and Kanjanapayont, 2022) (Figure 9). The foliations of high- and low-grade metamorphic rocks generally strike at a NNW–SSE trend, gently dipping toward both west and east directions. The foliations strike between 280° and 320° with dipping between 80° and 60°. Lineations are well developed within the high-grade metamorphic rocks. Orientations of the lineations generally trend 300°–330° and plunge toward the south. Microstructures of the D1a stage clearly indicate sinistral shearing. The high-grade metamorphic units are characterized by oblique foliation, elongated shape, mica fish, sigmoid shapes, strain shadow and σ-porphyroclasts of feldspar. Other microstructures are S–C and S–C′ shear bands. Oblique quartz grain shape fabric analysis and quartz c-axis CPO patterns clearly display sinistral movement. Within the Three Pagodas shear zone, the kinematic vorticity numbers of the mylonites indicate simple shear strain conforming with a kinematic vorticity number from the Fry method of 0.75–0.99 (Kanjanapayont et al., 2018). This sinistral movement of the Three Pagodas shear zone accords with the strike-slip system of the Mae Ping shear zone (Ponmanee et al., 2016), the Klaeng fault zone (Kanjanapayont et al., 2013), the Ranong and Khlong Marui shear zones (Watkinson et al., 2008; Kanjanapayont et al., 2012a). The timing of the sinistral strike-slip caused metamorphisms in this shear zone as indicated by U–Pb dating of the zircon rims from the mylonitic augen gneiss at 51–57 Ma (Nantasin et al., 2012). This time also aligns with the movement of the Mae Ping shear zone (Palin et al., 2013; Österle et al., 2019), the Ranong shear zone (Watkinson et al., 2011), the Khlong Marui shear zone (Kanjanapayont et al., 2012b) and may relate to the early of the Indian–Eurasian collision at about 50–65 Ma (Klootwijk et al., 1992; Molnar and Tapponnier, 1975; Searle, 2006; Searle et al., 2010).

Figure 9.

Figure 9

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Deformation stages of the Three Pagodas shear zone; D1a ductile sinistral shearing with metamorphism, D1b transpression tectonics, and D2 brittle dextral faulting.

6.1.1.2. D1b

D1b is characterised by transpressional tectonics and deformation (Kongsukko and Kanjanapayont, 2022) (Figure 9). The cooling ages of the Three Pagoda shear zone were estimated by K–Ar dating (Bunopas, 1981), Ar–Ar dating of biotite (Lacassin et al., 1997), Sb–Sr dating of biotite (Nantasin et al., 2012) and U–Pb dating of calcite (Simpson et al., 2021). These ages indicated the exhumation of the shear zone at around 33–35 Ma. We surmise that the transpressional tectonics exhumed the high- and low-grade metamorphic rocks to the upper level (Figure 9), possibly caused by principal stress along the E–W axis from the Indian-Eurasian collision (Rhodes et al., 2005; Morley, 2012).

6.1.2. D2

The last deformation D2 is represented by brittle NW-SE trending strike-slip movement (Kongsukko and Kanjanapayont, 2022) (Figure 9). The strike-slip faults in the Three Pagoda shear zone show dextral movement. This strike-slip system is not unlike an anomalous solution in aeromagnetic study (Tulyatid and Rangubpit, 2016). The younger structures at the surface is controlled by the systematic major fault. This fault system was developed an extensional pull–apart basin along the boundary axis of the Thabsila metamorphic complex (Rhodes et al., 2005). N–S trending minor fault locally occurs in some area. Timing of this deformational stage can be interpreted by the U–Pb dating of the calcite vein from metacarbonate mylonite at ∼48 Ma and ∼23 Ma (Simpson et al., 2021), and apatite fission tracks of 23–19 Ma (Upton, 1999). These ages relate to the strike-slip reactivation in Thailand (Morley, 2002) and decreasing maximum principal strain throughout clockwise rotation from the E–W to the N–S axis (Rhodes et al., 2005).

6.2. Strain variation of the ductile deformation

The strain variation of the ductile deformation phase or D1 is demonstrated by the kinematic vorticity number (Wk) (Table 1) and the pattern of the quartz c-axis CPO fabric analysis of the mylonites. The Wk between 0.82 and 0.99 imply that the Three Pagodas shear zone dominantly deformed under the simple shear during the strike-slip movement. Based on these variations, the Three Pagodas shear zone can be divided into western, central, and eastern parts (Figure 8).

In the eastern part of the shear zone, three samples, TB-09, TB-10 and TB-11, yielded the lowest strain values. The kinematic vorticity number (Wk) had an average value between 0.82 and 0.85. Samples TB-01, TB-07, TB-08, TB-19 and TB-23 from the central part had an average between 0.93 and 0.99, as did samples TB-18, TB-24 and TB-25 in the western part. These results indicate that the central and the western parts had more than 80% simple shear and less than 20% pure shear, whereas the eastern part of the shear zone has 60%–65% simple shear and 35%–40% pure shear components.

6.3. Tectonic implications

The deformation history of the Three Pagodas shear zone is associated with the Indian-Eurasian collision from Eocene to recent (Upton, 1999; Morley, 2002; Rhodes et al., 2005; Nantasin et al., 2012; Kanjanapayont et al., 2018; Kongsukko and Kanjanapayont, 2022). The northward continuous movement of the increased obliqueness of the Indian and Eurasian plate subduction affected the indentation moving of India into Asia (Molnar and Tapponnier, 1975; Tapponnier et al., 1982). This Indian-Eurasian collision initially resulted in compressive stress along the front of the Indian plate continent (Tapponnier et al., 1982). In this region, the horizontal compressive stress had an E–W orientation at around 40–50 Ma (Huchon et al., 1994). The continent of Sundaland gradually slid and southeastward extruded about 15° clockwise (Rhodes et al., 2005). Increasing NW-trending stresses possibly caused the sinistral strike-slip movement and metamorphism along the Three Pagodas shear zone, which is related to D1a. This rotation was between 15° and 45° from the E-W horizontal compressive stress (Maranate and Vella, 1986; McCabe et al., 1988). As the rotation continued, this stress shifted southeastwardly from E–W axis toward the N–S axis. The changing of the stress field would be influenced by transpressional tectonic and cooling of deep metamorphic rocks. It is possibly related to the D1b exhumation of the Thabsila metamorphic complex along the shear zone. When this rotation was ended, the horizontal compressive stress orientation had shifted >45°, and the direction of movement of the strike-slip faults had changed from the sinistral strike-slip of D1 to the dextral strike-slip of D2.

The deformation of the Three Pagodas shear zone during the Cenozoic is possibly linked to that of the Mae Ping shear zone (Lacassin et al., 1993, 1997; Palin et al., 2013; Österle et al., 2019), the Ranong shear zone (Watkinson et al., 2008, 2011) and the Khlong Marui shear zone (Kanjanapayont et al., 2012a, 2012b) as well as the metamorphic events in Thailand (Upton, 1999; Geard 2008; Nantasin et al., 2012; Kanjanapayont et al., 2013; Palin et al., 2013; Österle et al., 2019) and the early Indian–Eurasian collision (Molnar and Tapponnier, 1975; Klootwijk et al., 1992; Searle, 2006; Searle et al., 2010).

7. Conclusions

Both low- and high-grade metamorphic rocks are prominent in the Three Pagodas shear zone. Low-grade metamorphic metapelitic and metacarbonate rocks are presented by greenschist facies. High-grade metamorphic rocks, including migmatitic gneiss, augen gneiss, marble, schist, quartzite calc–silicate, are examples of amphibolite rocks that occur in the shear zone.

The deformation phases of the Three Pagodas shear zone are D1a, D1b and D2. D1a is sinistral ductile strike-slip shearing, shown by the NW–SE trending foliations and subhorizontal lineations from 300° to 330° plunging to the south. The kinematic vorticity number (Wk) from quartz c-axis CPO analysis of D1a is between 0.82 and 0.85 for the eastern part of the shear zone. The central and western parts of the shear zone have average values between 0.90 and 0.95. The kinematic vorticity numbers indicate that the eastern shear regime displays 60%–65% simple shear and 35%–40% pure shear components. The central and western parts show more than 80% simple shear and less than 20% pure shear. The strain variation reveals that the strike-slip shearing was more dominated in the central and western parts than the eastern part of the shear zone. The first deformation was contemporaneous with transpressional tectonics of D1b, which are related to exhumation of the metamorphic rocks to the upper level. D2 involves brittle deformation presented by the NW–SE trending dextral strike-slip faults.

Declarations

Author contribution statement

Sittiporn Kongsukho, M.Sc.: Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.

Pitsanupong Kanjanapayont, Dr.rer.nat.: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.

Funding statement

Dr. Pitsanupong Kanjanapayont was supported by Chulalongkorn University [CU-GR_63_86_23_16], Asahi Glass Foundation [RES_63_317_23_018].

Data availability statement

Data included in article/supp. material/referenced in article.

Declaration of interest’s statement

The authors declare no conflict of interest.

Additional information

No additional information is available for this paper.

Acknowledgements

The authors would like to thank the Department of Geology, Chulalongkorn University, Thailand for supporting all facilities of this research. We also thank editors Dr. George Iliopoulos and the two anonymous reviewers for constructive comments, which improved this manuscript.

Appendix A. Supplementary data

The following is the supplementary data related to this article:

Language Editing Certificate
mmc1.pdf (437.5KB, pdf)

References

  1. Bunopas S. Victoria University of Wellington; 1981. Paleogeographic History of Western Thailand and Adjacent Parts of Southeast Asia: A Plate Tectonic Interpretation; p. 810. Unpublished PhD Thesis. [Google Scholar]
  2. Charusiri P., Daorerk V., Archibald D., Hisada K., Ampaiwan T. Geotectonic evolution of Thailand: a new synthesis. J. Geol. Soc. Thai. 2002;1:1–20. [Google Scholar]
  3. Chung S.-L., Chu M.-F., Zhang Y., Xie Y., Lo C.-H., Lee T.-Y., Lan C.-Y., Li X., Zhang Q., Wang Y. Tibetan tectonic evolution inferred from spatial and temporal variations in post-collisional magmatism. Earth Sci. Rev. 2005;68(3):173–196. [Google Scholar]
  4. Chung S.-L., Lee T.-Y., Lo C.-H., Wang P.-L., Chen C.-Y., Yem N.T., Hoa T.T., Genyao W. Intraplate extension prior to continental extrusion along the Ailao Shan-Red River shear zone. Geology. 1997;25(4):311–314. [Google Scholar]
  5. Chung S.-L., Lo C.-H., Lee T.-Y., Zhang Y., Li X., Wang K.-L., Wang P.-L. Diachronous uplift of the Tibetan Plateau starting 40 Myr ago. Nature. 1998;394:769–773. [Google Scholar]
  6. Department of Mineral Resources . Department of Mineral Resources; Bangkok, Thailand: 2008. Geological Map of Thailand. scale 1:50,000. [Google Scholar]
  7. Faghih A., Soleimani M. Quartz c-axis fabric development associated with shear deformation along an extensional detachment shear zone: Chapedony Metamorphic Core Complex, Central-East Iranian Microcontinent. J. Struct. Geol. 2015;70:1–11. [Google Scholar]
  8. Geard A. University of Tasmania; 2008. Geology of the Klaeng Region (Southeast Thailand): Lithology, Structure and Geochronology. Unpublished BSc Honors Thesis. [Google Scholar]
  9. Huchon P., Le Pichon X., Rangin C. Indochina peninsula and the collision of India and Eurasia. Geology. 1994;22:27–30. [Google Scholar]
  10. Kanjanapayont P. In: Ductile Shear Zones: from Micro- to Macro-Scales. Mukherjee S., Mulchrone F., editors. Wiley-Blackwell; UK: 2015. Chapter 15 Strike-slip ductile shear zones in Thailand; pp. 250–269. [Google Scholar]
  11. Kanjanapayont P., Grasemann B., Edwards M.A., Fritz H. Quantitative kinematic analysis within the Khlong Marui shear zone, southern Thailand. J. Struct. Geol. 2012;35:17–27. [Google Scholar]
  12. Kanjanapayont P., Kieduppatum P., Klötzli U., Klötzli E., Charusiri P. Deformation history and U–Pb zircon geochronology of the high grade metamorphic rocks within the Klaeng fault zone, eastern Thailand. J. Asian Earth Sci. 2013;77:224–233. [Google Scholar]
  13. Kanjanapayont P., Klötzli U., Thöni M., Grasemann B., Edwards M.A. Rb–Sr, Sm–Nd, and U–Pb geochronology of the rocks within the Khlong Marui shear zone, southern Thailand. J. Asian Earth Sci. 2012;56:263–275. [Google Scholar]
  14. Kanjanapayont P., Ponmanee P., Grasemann B., Klötzli U., Nantasin P. Quantitative finite strain analysis of the quartz mylonites within the Three Pagodas shear zone, western Thailand. Austrian J. Earth Sci. 2018;111(2):171–179. [Google Scholar]
  15. Klootwijk C.T., Gee J.S., Peirce J.W., Smith G.M., McFadden P.L. An early India-Asia contact; palaeomagnetic constraints from Ninetyeast Ridge, ODP Leg 121; with suppl. Data 92-15. Geology. 1992;20:395–398. [Google Scholar]
  16. Kongsukko S., Kanjanapayont P. Petrography and deformation history of the three Pagodas fault, western Thailand. Bull. Earth Sci. Thailand. 2022;14/1:52–63. [Google Scholar]
  17. Lacassin R., Leloup P.H., Tapponnier P. Bounds on strain in large Tertiary shear zones of SE Asia from boudinage restoration. J. Struct. Geol. 1993;15:677–692. [Google Scholar]
  18. Lacassin R., Maluski H., Leloup P.H., Tapponnier P., Hinthong C., Siribhakdi K., Chauviroj S., Charoenravat A. Tertiary diachronic extrusion and deformation of western Indochina: structure and 40Ar/39Ar evidence from NW Thailand. J. Geophys. Res. 1997;102(B5):10013–10037. [Google Scholar]
  19. Law R.D. In: Deformation Mechanisms, Rheology and Tectonics. Knipe R.J., Rutter E.H., editors. Vol. 54. Geological Society, London, Special Publication; 1990. Crystallographic fabrics: a selective review of their applications to research in structural geology; pp. 335–352. [Google Scholar]
  20. Law R.D., Searle M.P., Simpson R.L. Strain, deformation temperatures and vorticity of flow at the top of the greater Himalayan Slab, Everest massif, Tibet. J. Geol. Soc. 2004;161:305–320. [Google Scholar]
  21. Leloup P.H., Lacassin R., Tapponnier P., Schärer U., Dalai Z., Xiaohan L., Liangshang Z., Shaocheng J., Trinh P.T. The Ailao Shan-Red River shear zone (Yunnan, China), tertiary transform boundary of Incochina. Tectonophysics. 1995;251:3–84. [Google Scholar]
  22. Lin T.-H., Chung S.-L., Chiu H.-Y., Wu F.-Y., Yeh M.-W., Searle M.P., Iizuka Y. Zircon U–Pb and Hf isotope constraints from the Ailao Shan–Red River shear zone on the tectonic and crustal evolution of southwestern China. Chem. Geol. 2012;291:23–37. [Google Scholar]
  23. Lister G.S., Williams P.F. Fabric development in shear zones: theoretical controls and observed phenomena. J. Struct. Geol. 1979;1(4):283–297. [Google Scholar]
  24. Maranate S., Vella P. Paleomagnetism of the Khorat group, Mesozoic, northern Thailand. J. Southeast Asian Earth Sci. 1986;1(1):23–31. [Google Scholar]
  25. McCabe R., Celaya M., Cole J., Han H.C., Ohnstad T., Paijitprapapon V., Thitipawarn V. Extension tectonics: the Neogene opening of the north-south trending basins of central Thailand. J. Geophys. Res. Solid Earth. 1988;93(B10):11899–11910. [Google Scholar]
  26. Molnar P., Tapponnier P. Cenozoic tectonics of Asia: effects of a continental collision. Science. 1975;189:419–426. doi: 10.1126/science.189.4201.419. [DOI] [PubMed] [Google Scholar]
  27. Morley C.K. A tectonic model for the Tertiary evolution of strike-slip faults and rift basins in SE Asia. Tectonophysics. 2002;347:189–215. [Google Scholar]
  28. Morley C.K. Late Cretaceous-early palaeogene tectonic development of SE Asia. Earth Sci. Rev. 2012;115:37–75. [Google Scholar]
  29. Morley C.K., Smith M., Carter A., Charusiri P., Chantraprasert S. Vol. 290. Geological Society of London, Special Publication; 2007. Evolution of Deformation Styles at a Major Restraing bend, Constraints from Cooling Histories, Mae Ping Fault Zone, Western Thailand; pp. 325–349. [Google Scholar]
  30. Nantasin P., Hauzenberger C., Liu X., Krenn K., Dong Y., Thöni M., Wathanakul P. Occurrence of the high grade Thabsila metamorphic complex within the low grade Three Pagodas shear zone, Kanchanaburi Province, western Thailand: petrology and geochronology. J. Asian Earth Sci. 2012;60:68–87. [Google Scholar]
  31. Österle J.E., Klötzli U., Stockli D.F., Palzer-Khomenko M., Kanjanapayont P. New age constraints on the Lan Sang gneiss complex, Thailand, and the timing of activity of the Mae Ping shear zone from in-situ and depth-profile zircon and monazite U-Th-Pb geochronology. J. Asian Earth Sci. 2019;181 [Google Scholar]
  32. Palin R.M., Searle M.P., Morley C.K., Charusiri P., Horstwood M.S.A., Roberts N.M.W. Timing of metamorphism of the Lansang gneiss and implication for left–lateral motion along the Mae Ping (Wang Chao) strike–slip fault, Thailand. J. Asian Earth Sci. 2013;76:120–136. [Google Scholar]
  33. Passchier C. The use of Mohr circles to describe non-coaxial progressive deformation. Tectonophysics. 1988;149(3-4):323–338. [Google Scholar]
  34. Passchier C., Trouw R.A. Springer Science & Business Media; 2005. Microtectonics. [Google Scholar]
  35. Polachan S., Pradidtan S., Tongtaow C., Janmaha S., Intarawijitr K., Sansuwan C. Development of Cenozoic basins in Thailand. Mar. Petrol. Geol. 1991;8:84–97. [Google Scholar]
  36. Ponmanee P., Kanjanapayont P., Grasemann B., Klötzli U., Choowong M. Quantitative finite strain analysis of high-grade metamorphic rocks within the Mae Ping shear zone, western Thailand. Austrian J. Earth Sci. 2016;109(2):233–240. [Google Scholar]
  37. Rhodes B.P., Charusiri P., Kosuwan S., Lamjuan A. 2005. Tertiary evolution of the three pagodes fault, western Thailand; pp. 498–505. (Proceedings of the International Conference on Geology. Geotechnlony and Mineral Resources of Indochina (GEOINDO 2005), November 28-30, 2005, Khon Kaen, Thailand). [Google Scholar]
  38. Richter B., Fuller M. Palaeomagnetism of the Sibumasu and Indochina blocks: Implications for the extrusion tectonic model. Geol. Soc. London Spec. Publ. 1996;106:203–224. [Google Scholar]
  39. Ridd M.F. The phuket terrane: a late palaeozoic rift at the margin of Sibumasu. J. Asian Earth Sci. 2009;36(2):238–251. [Google Scholar]
  40. Salypongse S., Santadgarn P., Hong P., Jatupornkongchai S., Chandon E., Putthapiban P. Transition between the Thabsila metamorphic complex and the Lower Paleozoic formations and their sandstone provenance, Kanchanaburi, western Thailand. Thai Geosci. J. 2020;1(1):27–46. [Google Scholar]
  41. Searle M.P. Role of the Red River shear zone, Yunnan and Vietnam, in the continental extrusion of SE Asia. J. Geol. Soc. London. 2006;163:1025–1036. [Google Scholar]
  42. Searle M.P., Yeh M.W., Chung S.L. Structural constraints on the timing of left-lateral shear along the Red River shear zone in the Ailao Shan and Diancang Shan ranges, Yunnan, SW China. Geosphere. 2010;6:316–338. [Google Scholar]
  43. Simpson A., Glorie S., Morley C.K., Roberts N.M.W., Gillespie J., Lee J.K. In-situ calcite U-Pb geochronology of hydrothermal veins in Thailand: new constraints on Indosinian and Cenozoic deformation. J. Asian Earth Sci. 2021;206 [Google Scholar]
  44. Spanos D., Xypolias P., Koukouvelas I. Vorticity analysis in calcite tectonites: an example from the Attico-Cycladic massif (Attica, Greece) J. Struct. Geol. 2015;80:120–132. [Google Scholar]
  45. Tapponnier P., Peltzer G., Le Dain A.Y., Armijo R. Propagating extrusion tectonics in Asia: new insights from simple experiments with plasticine. Geology. 1982;10:611–616. [Google Scholar]
  46. Tapponnier P., Peltzer G., Armijo R. In: Collision Tectonics. Coward M.P., Ries A.C., editors. Vol. 19. Geological Society of London, Special Publication; 1986. On the mechanism of collision between India and Asia; pp. 115–157. [Google Scholar]
  47. Tapponnier P., Lacassin R., Leloup P.H., Schärer U., Zhong D., Wu H., Liu X., Ji S., Zhang L., Zhong J. The Ailao Shan/Red River metamorphic belt: tertiary left–lateral shear between Indochina and South China. Nature. 1990;343:431–437. [Google Scholar]
  48. Tulyatid J. Queen’s University; Kingston, Ontario, Canada: 1991. A 40Ar/39Ar Geochronological Study of Deformed Meta-Granitoid Rocks Adjacent to the Hua Hin – Pran Buri Fault System, Peninsular Thailand; p. 103. [Google Scholar]
  49. Tulyatid D., Rangubpit W. Subsruface structure of Kanchanaburi area interpreted from aeromagnetic data. Chiang Mai J. Sci. 2016;43(6):1316–1323. [Google Scholar]
  50. Upton D.R. University of London; 1999. A Regional Fission Track Study of Thailand: Implication for thermal History and Denudation. Unpublished PhD Thesis. [Google Scholar]
  51. Wallis S.R. Vorticity analysis and recognition of ductile extension in the Sanbagawa belt, SW Japan. J. Struct. Geol. 1995;17:1077–1093. [Google Scholar]
  52. Watkinson I., Elders C., Hall R. The kinematic history of the Khlong Marui and Ranong faults, southern Thailand. J. Struct. Geol. 2008;30:1554–1571. [Google Scholar]
  53. Watkinson I., Elders C., Batt G., Jourdan F., Hall R., McNaughton N.J. The timing of strike–slip shear along the Ranong and Khlong Marui faults, Thailand. J. Geophys. Res. 2011;116(B9):1–26. [Google Scholar]
  54. Xypolias P. Some new aspects of kinematics vorticity analysis in naturally deformed quartzites. J. Struct. Geol. 2009;31:3–10. [Google Scholar]
  55. Xypolias P., Gerogiannis N., Chatzaras V., Papapavlou K., Kruchenberg S.C., Aravadinou E., Michels Z. Using incremental elongation and shearing to unravel the kinematics of a complex transpressional zone. J. Struct. Geol. 2018;115:64–81. [Google Scholar]

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