The structural evolution of the Bentong-Raub Zone and the Western Belt around Kuala Lumpur, Peninsular Malaysia

Jorien L.N. van der Wal MSc Thesis 2014 Supervisors: Dr Ernst Willingshofer, Dr Thomas Francois, Dr Liviu Matenco

ABSTRACT

To determine what deformed the inherited Bentong-Raub suture zone in western Peninsular Malaysia, a detailed field study in the area around Kuala Lumpur was conducted focussing on the various structural, metamorphic and kinematic features of the Bentong-Raub Zone and the surrounding Western- and Central Belts. The in-depth knowledge on large-scale structures and the tectonic origin of the study area was used to develop a tectonic model for the evolution of western Malaysia. Four deformation phases were recognized in the field, of which the most prominent one, D1, is a progressive deformation phase comprising two foliations, two folding geometries and coeval shear, and can be related to NE-SW shortening. Presumably, this deformation corresponds to accretionary wedge formation during northward subduction of the Paleo- Tethys Ocean beneath Indochina. Burial of sediments in this accretionary wedge led to the growth of biotite, muscovite, chlorite, garnet, quartz and feldspar under greenschist facies metamorphic conditions. Sedimentation and subsequent deformation and burial-related sub- greenschist facies metamorphism of a Triassic forearc basin recorded a second deformation event D2. Intrusion of the Triassic S-type Main Range Granites caused contact metamorphism in the surrounding metasediments and was followed by steep normal faulting (D3) and a later, regional strike-slip shearing event (D4). The combined effect of D3 and D4 is thought to have played a major role in the exhumation of western Peninsular Malaysia during Paleogene times. It is also suggested that this shear is related to Eocene formation of offshore sedimentary basins due to Indian-Eurasian collision and subsequent clockwise rotation of south-east Asia.

i Table of Contents

Abstract ...... i 1. Introduction ...... 4 2. Geological Setting ...... 6 2.1. Sibumasu Terrane ...... 8 2.2. Sukhothai Arc ...... 8 2.3. Oceanic rift basins ...... 9 2.4. The Bentong-Raub Zone ...... 9 3. Methods ...... 11 4. Results ...... 13 4.1. Field observations ...... 13 4.1.1. Lithologies & Metamorphism ...... 13 4.1.2. Ordovician-Silurian, Devonian & Bentong-Raub metasediments ...... 17 4.1.3. Triassic (meta-) sediments ...... 25 4.1.4. Main Range Granites ...... 28 4.1.5. Kinematics ...... 30 4.2. Thin section and SEM analysis ...... 32 4.2.1. Metasediments ...... 33 4.2.2. Granites ...... 37 4.2.3. Shear senses ...... 38 5. Discussion ...... 39 5.1. Interpretation of field & thin-section analysis ...... 39 5.2. Cross section ...... 45 5.3. Tectonic implications ...... 51 5.4. Is Bentong-Raub a suture? ...... 54 6. Conclusions ...... 55 Outlook ...... 56 Acknowledgements ...... 57 References ...... 58 Appendix 1 GPS Coordinates and orientation measurements ...... 60 Bentong-Raub zone ...... 60 Ordovician-Silurian east of Kuala Lumpur ...... 67 Ordovician-Silurian west of Kuala Lumpur ...... 73

ii Granites east of Bentong-Raub ...... 75 Granites west of Bentong-Raub ...... 77 Triassic ...... 81 Devonian ...... 85 Appendix 2 Thin section descriptions and scans ...... 92 Appendix 3 SEM-results ...... 102 Sample M9 ...... 103 Sample M15 ...... 104 Sample M24 ...... 107

iii 1. INTRODUCTION

Peninsular Malaysia comprises two tectonic terranes (fig. 1), which both originated from the supercontinent Gondwana and subsequently assembled in Late Triassic times (Metcalfe, 2013). The Sibumasu Terrane, now representing west Malaysia, separated from Gondwana in Early Permian (Sakmarian) times, during the opening of the Meso-Tethys. The Sukhothai Arc, a volcanic arc system that formed on the margin of the much larger Indochina Block/Terrane, represents Central and Eastern Peninsular Malaysia (see figure 1). The Indochina Block separated from Gondwana in Devonian times and Sibumasu was separated from Australia/Gondwana by Late Permian times. The volcanic-plutonic Sukhothai (island) Arc formed during northward subduction of the Paleo-Tethys Ocean beneath the Indochina Block in Late Palaeozoic (Permian) times. The subduction of the Paleo-Tethys Ocean was followed by the collision of the two tectonic terranes and subsequent initiation of orogenic deformation in Lower Triassic times. In Late Triassic-Early Jurassic times, as a consequence of the A-type subduction of the Paleo- Tethys Ocean beneath Indochina, S-type syn- to post-orogenic granites were emplaced (pink coloured units in Fig. 2). These granites, representing the main topographical highs of Peninsular Malaysia, are known as the Main Range granites. They separate accretionary wedge deposits of the Bentong-Raub Zone, from the foredeep deposits of the Semanggol Formation in NW Peninsular Malaysia that formed on the depressed Sibumasu margin (Metcalfe, 2013).

Fig. 1 Overview of the various tectonic terranes which together form the geology of Peninsular Malaysia in its large-scale tectonic setting (François, 2015). Suture zones are highlighted by red lines. The dotted red line going through Peninsular Malaysia (blue outline) is the Bentong-Raub zone (Wakita & Metcalfe, 2005; in Hutchison, 2007).

4 The boundaries between the north-south trending belts that characterise the Palaeozoic and Early Mesozoic geology of Peninsular Malaysia are thought to represent the outlines of paleo- subduction sutures (Tan, 1996; red lines in fig. 1). Specifically, the narrow zone separating the Western Belt (i.e. Sibumasu Terrane) from the Central and Eastern Belts (i.e. Sukhothai Arc), known as the Bentong-Raub Zone, has been proposed to represent the Paleo-Tethys suture. It has also been suggested that this Bentong-Raub Suture can be connected to the Nan- Uttaradit and the Chiang-Mai/Chiang-Rai sutures in northern Thailand, as well as the Sra Kaeo suture in SE Thailand (Metcalfe, 2000). However, in contrast to the Thailand suture zones, less geological evidence exists to state with (relative) certainty that the Bentong-Raub Zone is indeed a suture.

The Bentong-Raub Zone is classically envisaged as a deep water accretionary prism with ophiolitic and volcanic mélange defined at the western boundary of the Central Belt. However, similar outcrops have also been reported from other locations. The uncertainty regarding the geological history of the Bentong-Raub Zone is mainly due to the lack of structural, metamorphic and kinematic data of the Bentong-Raub Zone itself and the surrounding lithological units. Up to date, detailed information is essential to answer the main questions regarding the geological history of Peninsular Malaysia. Besides the main question regarding the role and significance of the Bentong-Raub Zone in the geological history of Peninsular Malaysia, the mechanisms of the exhumation of the central granites and the deformational and metamorphic evolution of the surrounding rocks is largely unknown. In this research, a detailed study was conducted of the deformational and metamorphic structures and textures within different lithologies of the Bentong-Raub Zone itself and the Central Belt (fig 2) along a NE-SW oriented transect with the aim to increase our understanding of the deformation history of the Central Belt and its relationship with the Bentong-Raub suture. More specifically, the aim is to find out what is deforming the inherited suture zone. For this purpose structural, metamorphic and kinematic field data documenting the various deformation phases throughout the Western Belt, the Bentong-Raub zone, and part of the Central Belt, was acquired. This field data was complemented with thin section analysis focused on metamorphic mineral assemblages and microstructures.

Fig. 2 Map and location of study area. Thin olive-green, black rimmed NW-SE trending belt is the Bentong-Raub Zone. Red dots are locations where field data was collected. Pink colours are intrusive bodies. Scale of this cut-out of the large map is 1:1000.000 (Derived from the map published by the Geological Survey, 1985)

5 2. GEOLOGICAL SETTING

A geological division of the Malay Peninsula into three separate north-south trending zones was initially proposed by Scivenor (1928), and it was based solely upon the differences in mineralization styles. Geologically, Peninsular Malaysia is now subdivided into the Western, Central and Eastern Belt (see fig. 3). The Bentong-Raub Zone separates the Western from the Central Belt.

Fig. 3 Geological division of Peninsular Malaysia into the Western, Central and Eastern Belts, including their differently aged plutons. Also shown are the Bentong-Raub Zone, the Bukit Tinggi and Kuala Lumpur fault zones. (Adapted from Oliver et al., 2013)

Tectonically, the entire Malay Peninsula is part of the SE Asian continental core of Sundaland (Metcalfe, 2013; see fig. 1). All principal continental blocks that are part of Sundaland (i.e. the South China, Indochina, West Burma, West Sumatra and SW Borneo blocks and the Sibumasu terranes), were detached from Gondwana during three episodes of rifting, separation and northward drifting during the successive opening and closing of three ocean basins. These ocean basins represented the Paleo-Tethys, Meso-Tethys and Ceno-Tethys, during Devonian – Triassic, late Early Permian – Late Cretaceous and Late Triassic – Late Cretaceous times, respectively. The subdivision of the Peninsula into different N-S trending zones represents the origin of each of the terranes which were assembled by Late Triassic times. The Western Belt of Peninsular Malaysia has been ascribed to the Sibumasu Terrane, which was derived from NW Australia during Early Permian, when it represented the Gondwana margin. The Eastern and Central Belts are considered to be part of the Sukhothai Arc which was constructed in the Late Carboniferous – Early Permian on the margin of the Indochina Block, which was in its turn derived from the margin of Gondwana in the Early Devonian. The arc is thought to have formed due to northward subduction of the Paleo-Tethys, and was subsequently separated

6 from Indochina during back-arc spreading. Accretion of the Sukhothai Arc back onto Indochina by back-arc collapse, as well as collision of Sibumasu with Indochina due to northwards subduction of the Paleo-Tethys, occurred in Triassic times(Metcalfe, 2013;see paleogeographic reconstruction in fig. 4). More detailed information on the geology of the Sibumasu Terrane and Sukhothai Arc will be provided in chapters 2.1 and 2.2.

Fig. 4 Paleogeographic reconstructions of the Tethys region/ Southeast Asia through time, showing northwards subduction of the Paleo-Tethys and subsequent collision of Sibumasu with Indochina. Most important abbreviations are: B.R. = Bentong-Raub, I= Indochina; E.M. = East Malaya/Sukhothai Arc; S = Sibumasu. (Based on Wakita and Metcalfe, 2005; from Hutchison, 2007)

7 2.1. Sibumasu Terrane Besides the Western Belt of the Malay Peninsula, the Sibumasu Terrane comprises the Shan Plateau of Burma, Northwest Thailand, Peninsular Burma and Thailand and NE Sumatra. It is possible that the terrane even extends as north as southwest China (Hutchison, 2009). The oldest rocks that have been dated within this terrane are middle Cambrian-Early Ordovician clastics from various formations in NW Peninsular Malaysia, southern and western Thailand. The crust underlying the Sibumasu Terrane has been dated to 1500-1700 Ma, based on Nd-Sr and U-Pb zircon dating of Permian-Triassic granitoids, and basement ages are generally Paleoproterozoic, ranging roughly from 1.9-2.0 Ga (Metcalfe, 2013). Studies from various disciplines, ranging from biogeographic to tectonostratigraphic and paleomagnetic, imply that the origin of the terrane lies in NW Australia, during Cambrian- Early Permian times.

Volcanic components in the Western Belt comprise a.o. Upper Cambrian – Ordovician – Lower Silurian foliated rhyolitic tuffs occurring as scattered bodies (Ghani, 2009). Granitoids are S-type, felsic and they are probably related to intracratonic rifting on the margin of Gondwana. Also, Triassic rhyolites and rhydocites have been related to Main Range granitoid intrusions, and, although volumetrically small, they may be remnants of larger felsic Main Range volcanics (Metcalfe, 2013, Ghani, 2009).

2.2. Sukhothai Arc Bounded by a variety of suture zones (Metcalfe, 2013), the basement of the Sukhothai Arc has been determined to be continental, and it is thought to represent the western continental margin of the Indochina block, comprising a granulite facies metamorphic core. U-Pb zircon dating has shown that this granulite facies metamorphism occurred at 254 Ma, and Nd model ages suggest a 1.2-2.4 Ga crustal formation age. The basement is suggested to be Proterozoic and ages vary from 1100-1400 Ma to 1.7-2.0 Ga. Construction of the Sukhothai Arc was initiated in latest Carboniferous – Early Permian times on the margin of the South China – Indochina ‘superterrane’, by northwards subduction of the Paleo-Tethys. This was followed by back-arc spreading during the Early – Middle Permian, separation from Indochina and the subsequent opening of a back-arc basin and finally by the accretion to the South China – Indochina terrane by back-arc collapse during the Triassic. Volcanism in the Eastern and Central Belts of the Malay Peninsula is common, generally I- type and dates early Middle Permian – early Late Triassic, and they are thus related to subduction (Metcalfe, 2013). A major change in volcanic geochemistry is observed, from andesitic in Permian times to felsic in the Middle Triassic. The cause of this has been suggested to be collision of the Sukhothai Arc with the Sibumasu Terrane and the stop in subduction during the Middle Triassic. The Central Belt consists mainly of Permian-Carboniferous basin sediments (limestones, argillites) as well as associated calc-alkaline rhyolite–andesite volcanics and continental redbeds. The Eastern Belt also comprises sediments of Permian – Carboniferous age, as well as rhyolite-andesite volcanics associated to the Sukhothai Arc (Oliver et al., 2013). Fossils of Permian age reveal a contrasting warm climate in the Eastern Belt to the cold climate of the Western Belt (Sone and Metcalfe, 2008).

8 2.3. Oceanic rift basins Peninsular Malaysia is bounded in both east and west by oceanic rift basins. These Cenozoic basins, some of which are also found on-shore, are thought to have developed due to regional escape tectonics on continental blocks (Morley, 2001; 2012). Both NW-SE and NE-SW strike-slip faults have been documented throughout SE Asia. Shear senses along these strike- slip faults are dominantly sinistral or left-lateral during Tertiary times. Recently analysed movement along major strike-slip fault zones however show dextral movement. It has been suggested by Taponnier et al. (1986) that this change in movement along major faults occurred in Late Miocene. Polachan et al., 1991, state that the NW-SE striking strike-slip extensional faults which are the structural framework of the Cenozoic basins, are the principal strike-slip faults and NE-SW oriented faults are conjugate sinistral faults. Strike-slip faults in Thailand are ascribed to a change in the angle of subduction from perpendicular to oblique (Pubellier, 2004). This occurred due to the progressive clockwise rotation of SE Asia supposedly from NW-SE to N-S, by the northward movement of India (collision since 40-50Ma). The resulting (accelerated) strike-slip movement is subsequently related to the transtensional Cenozoic pull-apart basin development (Polachan et al., 1991). Active strike-slip deformation was most important prior to 30 Ma (Morley, 2001).

Morley (2001), suggests that the Cenozoic basins might not have been formed due to strike- slip faulting but that slab roll-back might have played a significant role in the development of the basins. The timing and origin of basin development is, according to Morley (2001), related to subduction roll-back of the Indian Plate.

2.4. The Bentong-Raub Zone The collision of the Sibumasu terrane with the Sukhothai Arc has been dated to Early Triassic – Late Triassic times. This collision was accompanied by the deposition of sediments in a foredeep basin within an accretionary complex and the intrusion of S-type granites in the Western Belt and Bentong-Raub zone during Late Triassic – earliest Jurassic, due to crustal thickening, slab break-off and the rising of hot asthenosphere (Metcalfe, 2013). Following the collision between Arc and Terrane, a back-arc basin opened, collapsed and closed over a time interval ranging from Early Permian to Middle-Late Triassic, and successively, continental red beds were deposited. A late Cretaceous thermal event caused major faulting, granitoid intrusions and a widespread resetting of paleomagnetic signatures (Metcalfe, 2013).

The Sibumasu terrane and Sukhothai Arc components of the Malay Peninsula are separated by the Bentong-Raub zone, of which the origin remains a point of discussion. Metcalfe (2000; 2013), as well as his predecessors among which are Hutchison (1977) and Mitchell (1977), argue that the Bentong-Raub is a suture zone, representing the remnants of the main Paleo- Tethys ocean basin (Devonian-Permian) which subducted beneath the Sukhothai Arc, producing Permian – Triassic volcanism and I-type granitoid intrusions in the Central and Eastern Belts of the Malay Peninsula. The alignment of the Bentong-Raub zone with Chiang Mai and Nan River Belts in Thailand is used to argue the suture zone origin of Bentong-Raub. In such a subduction-collision model, the Central Belt would either represent a back-arc, fore- arc, fore-arc/intra-arc or post-suturing extensional basin (Shuib, 2009). It must however be noticed that no evidence of ultrahigh pressure (UHP) metamorphism or an ophiolitic sequence has been reported to date.

Opposing the suggestion made by Metcalfe and his predecessors that the Bentong-Raub is a suture zone, it is argued by Tan and Khoo (1981) and in later papers by Tan (1984, 1993,

9 1996), that the serpentinised ultramafics are not remnants of an ancient oceanic lithosphere. Tan and Khoo argue that the spread and non-linear distribution of serpentinite bodies in the Peninsula, as well as the lack of any other features related to ophiolitic belts (i.e. tectonic mélange, deep sea sediments, calc-alkaline volcanism, etc.), convincingly show that the Bentong-Raub zone cannot be a suture. In Tan (1984) it is proposed that the Bentong-Raub represents a major normal fault forming the western boundary of the Central Belt graben or Triassic back-arc basin (Shuib, 2009).

10 3. METHODS

Structural fieldwork has been conducted in the area around Kuala Lumpur to analyse the structural and metamorphic geology and to reconstruct the tectonic and kinematic evolution of the Bentong-Raub zone and the surrounding rocks. The study area ranged approximately from Shah Alam (W) to Temerloh (E), and from Nilai (S) to halfway Kuala Lipis and the Cameron Highlands (N) (see figure 5). The Bentong-Raub zone is present along most of the N-S length of the study area, but in E-W transect, it does not exceed a width of 10-15km.

Fig. 5 All field locations (blue) and towns listed for reference. Black line shows the location of the cross section; dotted line is parallel to an average fold axis, along which measurements were transferred to the cross section. Adapted from Geological Survey of Malaysia, 1985.

Although almost 200 locations within the study area were visited, not all outcrops were suitable for collecting structural and metamorphic data. Many outcrops were severely affected by weathering, thus making mineralogical features, as well as both planar and linear structures either indistinguishable or impossible to measure. Nevertheless, over 950 orientation measurements of bedding planes, foliation planes, lineations, fault planes and fold structures were taken. Analysis of these measurements was done by plotting both planes and lineations in stereographic projections in the program Stereonet v9.0 (Allmendinger, 2006).

Kinematic information was retrieved from interpreting sigma and delta clasts as well as shear bands. In brittle structures, kinematic information was gathered based on slickensides and – lines on fault planes, Riedel shear systems and drag along faults. Where possible, rocks displaying structural or mineralogical features requiring further, detailed research were sampled (with geological hammer and chisel), for thin section analysis. Strike and dip measurements were recorded on oriented samples.

11 Thin section analysis was done by means of optical microscopy. Besides analysing structures and shear senses in the oriented samples, the mineralogy of each thin section was used to determine the metamorphic grade. In some cases, optical microscopy did not provide sufficient detail in determining the types of minerals present and chemical analysis was required. By means of the table-top Scanning Electron Microscope (SEM) available at Utrecht University, carbon coated thin sections were subjected to an electron beam, and Energy Dispersive X-ray spectroscopy (EDS) was used to develop spectra displaying the chemical composition of the measured mineral.

In order to get an overview of the structures observed in the field, their relationship to one another and their lateral continuity, a cross section has been constructed cross-cutting all lithological units. The size of the study area made it impossible to include all field data on this single cross section, however observations of e.g. fold geometries from all outcrops were taken into account to develop a complete picture of the large-scale structure. The cross section was developed approximately perpendicular to the strike of the Bentong-Raub and Western Belt, i.e. at 50° (fig. 5). Distal field observations/measurements were transferred to the cross section along the azimuth of an average S1 fold axis (i.e. along maximum continuity of geometric features) of 150°.

12 4. RESULTS

In the following chapter the various lithologies observed within the study area will be described, including their structural features and overprinting criteria used to establish the relative order of events. Also, thin section observations will be incorporated (section 4.2). Names of the different units have been extrapolated from the geological map (Geological Survey of Malaysia, 1985).

4.1. Field observations

Observed deformation structures and related metamorphic petrology within the study area will be described in the following section, and will subsequently be attributed to a certain deformation phase implying their relative timing.

4.1.1. Lithologies & Metamorphism

Meta-sedimentary lithologies vary between the different units, depending on the types and timing of the deposits. Overall, metamorphism in the study area did not exceed (sub-) greenschist facies conditions. To the west of Kuala Lumpur, the dominant lithologies are very low grade metamorphic rocks such as slates and phyllites. High grade metamorphic minerals are not observed, though circular oxidated iron accretions in Ordovician-Silurian metasediments just west of the Main Range Granites might indicate the presence of e.g. garnet. To the east of Kuala Lumpur, some outcrops display a higher metamorphic grade. A single outcrop of Ordovician-Silurian (OS) rocks separating the Main Range Granites from the Bentong-Raub zone, shows an abundance of garnet and graphite, implying metamorphism at higher pressures than in other OS outcrops. Schists in the Bentong-Raub zone are sometimes rich in biotite, which is not observed elsewhere.

Other (less-metamorphosed) lithologies vary depending on the timing and environment of deposition. The oldest deposits, of Ordovician-Silurian age, generally display an alternation of quartz- and mica-rich layers (fig. 6D), implying deposition in a shallow marine environment. A similar depositional environment is implied for the Devonian, Bentong-Raub and Triassic schists/phyllites and slates. The Bentong-Raub Zone also includes (scattered) outcrops of unmetamorphosed and barely deformed limestone and sandstone, probably deposited in a lagoon or intermediate marine-, and coastal/continental environment, respectively. It is not entirely clear what the age of these bodies is, thus it is not clear whether these rocks are deposits of a younger age than the deformation, metamorphism and uplift of the surrounding lithologies, or whether they form large lenses of undeformed rock around which the regional shear was concentrated. The most distinctive outcrops of the Bentong-Raub zone, however, are cherts/slates with pyroclastic input. This pyroclastic input consists of clasts which are both rounded and angular, lacking a clear structure. Only in a few cases did the surrounding foliation affect the internal structure of the pyroclastic clasts. In some locations (ribbon) cherts are seen which display a distinct intercalation of white and black chert layers (fig. 6A & B) which have undergone soft-sediment deformation and which also contain cm-m clasts of undeformed and unmetamorphosed sandstone and pyroclastics (see figure 6C). The Bentong-Raub zone is partly overlain by Jurassic-Cretaceous red-coloured conglomerates with chert- and clastic pebbles which only rarely display a foliation in the matrix. No granite

13 clasts were observed. The contact between chert sediments and these conglomerates is observed as a fault showing the conglomerates being thrust over the cherts towards the west. Several small bodies of serpentinite are found in the Bentong-Raub Zone (fig. 6E), which are probably a result of the alteration of ultramafic bodies rich in olivine. In one location, along the road from Sungai Kayan to the Cameron Highlands, a possible protolith was found in the proximity of a serpentinite outcrop. This rock (fig. 6F), rich in olivine, serpentine, clino- pyroxene and plagioclase, is probably olivine-diabase.

A B

C D

E F

Fig 6 Typical Bentong-Raub lithologies. A) Chert outcrop with clear bedding planes; B) Detail of A, showing soft sediment deformation, pop-up structure; C) Pyroclastic clast within country rock; D) Biotite schist displaying two foliations, S2 is the axial plane of S1; E) Fibrous serpentinite; F) Possible protolith of serpentinite

14 The Main Range granites, i.e. the large intrusive body cross-cutting the Western Belt, are S- type granites. In numerous outcrops large feldspar blasts, abundant hornblende and quartz, and clean/fresh biotite minerals (see fig 7A) are observed. In some localities euhedral feldspars reach up to 6 cm in length and their alignment indicates magmatic flow. In other outcrops, grain sizes of quartz and feldspar crystals are slightly smaller and almost homogeneous in size, amphibole and biotite are less abundant (fig. 7B). Fault planes and joints with chlorite crystals occur as well, implying fluid flow along these planes. Meta- sediments adjacent to the granite intrusion sometimes contain small epidote, amphibole and tourmaline crystals, indicating contact metamorphism.

Fig. 7 A) Seemingly undeformed granite with large feldspars; B) Sheared granite; foliation is parallel to pencil.

The structures that are observed in these various lithologies have been separated into different deformation phases based on their cross-cutting relations. Table 1 shows the relative timing of the observed structures which will be described in more detail in sections 4.1.2 – 4.1.4.

15 Ordovician-Silurian Devonian Bentong-Raub Triassic Granites

D1 NW-SE striking S0 & S1 ; N-S striking S2; SE-plunging F1 folds; NW-SE trending F2 and F3 fold axes; NW and SE plunging stretching lineations

(sub-) greenschist (sub-) greenschist facies; M1 (sub-) greenschist facies facies; local biotite locally (E) higher pressures growth NW-SE striking S0, S1 and S2 planes; NW-SE trending F1 and F2 fold axes; NNW-SSE trending D2 & stretching lineations. M2

Very low-grade metamorphism of sediments to shale Minor development of higher-temperature M3 minerals in lithologies Granite intrusion adjacent to granite intrusion NW-SE trending steep foliation S1; Localized shearing e.g. in Bukit Tinggi Fault Zone. D3/D4

Development of L2; NW-SE strike-slip shear NW-SE strike-slip shear (?) Local NW-SE strike-slip shear (?), e.g. in Kuala Lumpur Fault Zone

Table 1 Deformation structures observed in the field, set to the lithological unit in which they were observed, and to the associated deformation phase. Metamorphic events are also listed.

16 4.1.2. Ordovician-Silurian, Devonian & Bentong-Raub metasediments

Throughout the study area, meta-sediments are observed to have been strongly affected by deformation. In most lithologies, with the exception of Triassic sediments east of Bentong- Raub, bedding planes are subparallel to S1 foliation, and the only remnant of S0 is the intercalation of quartz- and mica-rich layers. Overall, the dominant planar structure in most outcrops is S1. This foliation is often observed to be isoclinally folded, creating a second foliation S2, parallel to the axial planes of these folds. In some Devonian (west of Kuala Lumpur) and Ordovician-Silurian outcrops this S2 foliation sometimes dominates as well. S2 foliation planes are sometimes observed as open folds, refolding the axial planes (S2) of the isoclinal folds. The axial plane of the latter, open folding structure is not observed as a planar feature throughout the study area (e.g. fig. 8). Overall, all these structures are considered to have formed in a single deformation event, D1. When analysing the orientations of the (poles to the) foliation planes of S1 and S2 altogether (i.e. from all units; fig. 17), it is clear that a (E)NE-(W)SW shortening direction was necessary to cause these deformation structures.

Fig. 8 Interpretation of a refolded isoclinal recumbent fold in an Ordovician-Silurian outcrop, east of Kuala Lumpur. S3 not observed in the field. Stop 30.3.

Analysing the structural data from different units separately shows that in the Bentong-Raub zone bedding planes are observed mostly as the intercalation between black and white chert deposits, often showing soft-sedimentary folding. The dominant shortening direction recorded in the bedding planes is NE-SW, which is similar to the shortening directions observed in the S1 and S2 foliations (figure 10). Bedding planes, as well as S1 and S2 foliation planes within the Bentong-Raub zone are generally steeply dipping. The larger extent of scatter in S2 data compared to S1, is probably due to the post-S2 open folding.

The Ordovician-Silurian unit is quite variable in E-W transect. This variability is the reason that in analysing the structural data, a separation is made between the Ordovician-Silurian unit west (OSW) of Kuala Lumpur and east (OSE) of Kuala Lumpur. East of Kuala Lumpur, a large scatter in S1 foliation plane measurement is observed (fig. 10), generally showing an ENE-WSW to NE-SW shortening direction. The dip of these foliation planes varies from intermediate to steep. The same is observed in S2 foliation planes, however the shortening direction of this deformation structure is more E-W or WNW-ESE. West of Kuala Lumpur only steeply dipping S2 foliation planes are observed, showing an obvious WNW-ESE shortening direction. Insufficient data was available on the orientation of

17 S0 in general, and S1 was observed with difficulty in the outcrops west of Kuala Lumpur due to the near-parallel orientation of isoclinally folded S1 planes and S2 planes.

Devonian outcrops west of Kuala Lumpur are heavily folded and faulted (e.g. fig. 9), causing a large scatter in S1 and S2 plane orientations (fig. 10). S1 foliation planes are generally shallow dipping and do not show a clear shortening direction. S2 foliation planes vary in dip from shallow to intermediately steep (fig. 10). Despite the scatter in data, an overall NE-SW shortening direction is interpreted.

Fig. 9 Field sketch of minor thrust faults in Devonian meta-sediments.

Fig. 10 Stereographic projections of the poles to various foliation- and bedding plane orientations, separated per lithological unit

18 Fold axes of the isoclinal folds affecting the S1 foliation and resulting in the formation of S2 foliation planes, show a NW-SE trend (fig. 11), and thus resulted from NE-SW shortening. Soft-sediment deformation of the chert layers in the Bentong-Raub zone shows a SE cluster of fold axes, also implying NE-SW shortening. In the Devonian outcrops west of Kuala Lumpur, the large-scale (and small-scale) recumbent isoclinal fold hinges sometimes outcrop as sheath- like structures as is seen in figure 12C. Mostly, however, refolded isoclinal folds similar to the ones in figures 11A and 11B are observed. Open folds affecting S2 foliation planes also show a NW-SE trend in the Ordovician-Silurian outcrops, especially east of Kuala Lumpur. In the west, open folds in the strongly deformed Devonian outcrops show a less obvious NW-SE trend; a NE-SW trend might also be interpreted. The axial planes of these open-style folds cannot be distinguished in the field as a separate planar structure (e.g. fig. 12A&12B). However, very rarely, asymmetric folding is observed as a later deformation structure crosscutting the S2 foliation. Perhaps these small folds are parasitic folds of the large scale open folding and thus their axial plane can be taken to represent a third foliation S3 (figure 12D)1. Besides the strong folding of the Devonian rocks, small-scale thrust faulting (often interacting with the folding, but only observed in 2D) is observed as well (see fig. 9). Figure 13 shows the distribution of fold axis orientations throughout the study area.

Fig. 11 Stereographic projections of various fold axis, separated per lithological unit

1 Fig. 12 (next page) Details of Devonian outcrops. A) interpretation of an openly refolded isoclinal recumbent fold; B) Interpretation of a refolded isoclinals recumbent fold; C) Hinge of isoclinals recumbent fold; D) Interpretation of S1, S2 and possibly S3 foliation. Colour coding to different foliations: S1 = red; S2 = orange; S3 = green

19 A B

C D

20

Fig. 13 All fold axes measured in the study area. Arrows point toward plunging direction of fold axis.

Shearing is observed on S1 foliation planes as NW-SE oriented stretching lineations (L1), seen specifically by the elongation and alignment of quartz and fine-grained mica crystals. The orientation of the foliation planes on which these lineations were measured indicate dominant NE-SW shortening, therefore showing that elongation is perpendicular to shortening. In the Bentong-Raub zone, stretching lineations are also observed to plunge to the SW, but a NW-SE trend seems to dominate (fig. 14). Both shallow and steeply plunging stretching lineations were measured. Figures 15 and 16 show two fault planes along which thrusting occurred. Besides obvious eastward thrusting within the cherts themselves (fig. 16), westward thrusting of (Jurassic) conglomerates over chert is also observed in the Bentong-Raub zone. The small grain size of the Bentong-Raub cherts and slates, as well as the influence of later folding and shearing, made it difficult to observe shear senses in the field. Thus, samples were taken for thin section analysis, of which the results will be discussed in chapter 4.2.

21 In other lithological units, less steep stretching lineations were measured. Field observations of Ordovician-Silurian shear senses, east of Kuala Lumpur, dominantly indicate top to SE movement, some top to NW movement is also observed (fig. 14). Measurements of L1 stretching lineations west of Kuala Lumpur are scarce, yet they seem to dominantly plunge (shallow) southward and show a top to north shear sense. Devonian meta-sediments show westward shallow plunging stretching lineations, of which no clear shear senses could be determined.

The similarity in timing and orientation of deformation between the NE-SW folding of S2 foliation planes and NW-SE shearing structures leads to the interpretation that these structures developed simultaneously. In stereographic projection, the poles to these foliation planes lie on a great circle perpendicular to the stretching lineations measured on S1 foliation planes, parallel to S2 fold axes. The inconclusive shear senses and stretching orientations also support this theory of coeval folding and shearing. Due to the overall NE-SW shortening direction observed from S1 foliations (subparallel to S0), subsequent isoclinal folding and simultaneous formation of the S2 foliation, as well as coeval open folding and shearing of these S2 planes, all these deformation structures are thought to be part of a progressive deformation phase, D1 (fig. 17).

Fig. 14 Stereographic projections of various stretching lineations per unit observed on either S1 planes (L1) or on S2 planes (L2).

22

Fig. 15 Thrust contact conglomerates and Fig. 16 Thrust fault plane within cherts, cherts in Bentong-Raub Zone, outcrop 1.3. outcrop 1.5. Red lines are parallel to Red lines are parallel to the stretching slickensides, thick black arrows indicate a lineation, thick black arrows indicate top to E transport direction. transport direction (top to W).

23 Fig. 17 Stereographic projections of D1deformation structures; i.e. incorporating all foliations, fold axes and stretching lineations associated with D1. L1 is either associated with folding phases F2 or F3. 1% area contour lines used.

24 On S2 foliation planes, a second phase of shearing is observed as stretching lineations L2 (fig. 18). The stretching lineations associated with this deformation are shallow-plunging and often indicate a dextral shear sense. The timing of this shear remains unconstrained. However, because stretching lineations associated with this shear are found on S2 folded foliation planes (lineations themselves are not folded), and because some similar shearing might also occur in Triassic and granitic outcrops, this structure is considered to be relatively young. In Ordovician-Silurian rocks clear dextral shear is seen along L2. In Devonian outcrops, shear senses implied either shallow-dipping normal faults or dextral strike-slip movement, towards the west. This shearing event will be further referred to as D4.

Fig. 18 Stereographic projection of stretching lineations found on S2 foliation planes; 1% area contour

4.1.3. Triassic (meta-) sediments

The second deformation phase (D2) recognized in the study area is fairly similar to D1, yet it has a different structural expression in a different lithology. The (Permo-) Triassic is the most weathered, undeformed and unmetamorphosed lithological unit. Triassic rocks are mostly sedimentary (limestone or sand/siltstone), yet they are, in some places, strongly deformed and sometimes metamorphosed to shales (sub-greenschist facies). The bedding planes of these Triassic sediments are asymmetrically folded (F1), show a southwest-ward vergence (axial planes dip east) and display an axial plane foliation, S1 (see fig. 19A and 19C). In one outcrop two cross-cutting fold structures were observed in S1, i.e. a fold that could be traced in three dimensions showed folding on two perpendicular outcropping planes (see fig. 19B and D). This implies a second foliation must be present, however little evidence was found in the field regarding the orientation of this foliation. Fold axes of F1 (folding S0 planes) and F2 (folding S1 planes) folds trend NW-SE (see fig. 20).

Triassic rocks display fairly shallow bedding planes (S0) that generally dip NE or SW, with some exceptions of somewhat steeper bedding planes of which some dip NW or SE (fig. 20). The axial plane foliation, S1, of the asymmetrically folded, W-vergent S0, shows a NE-SW shortening direction and dominantly steeply dipping foliation planes. Due to the difference in fold geometries (and later time of deposition) with the meta-sediments west of the Bentong- Raub zone, it is assumed that deformation in the Triassic rocks occurred at a later stage but pre-granite intrusion, and it is therefore referred to as D2.

25 Observed lineations are mostly intersection lineations between S0 and S1. However, in the low-metamorphic rocks some stretching lineations have been observed. The overall trend of all lineations is NNW-SSE (fig. 20), and the gradient of the lineations varies from horizontal to very steep and almost vertical. Along steeper lineations, dominant normal movement is observed; due to folding the direction of movement varies from top to E-NE. Shear senses of strike-slip (sub-horizontal) shears are less constrained, a single observation showed sinistral shear.

A B

C D Fig. 19 Asymmetric folding of S0 in Triassic sediments (outcrop 1.1). Fig. C is a field sketch of figure A; figure B shows W-vergent asymmetric folding., figure D is the third dimensional plane of the outcrop in fig. B, also showing folding (outcrop 6.5).

26

Fig. 20 Stereographic projections of D2 phase deformation structures; i.e. incorporating S0 bedding, S1 foliation, fold axes of S0 folds (F0) and S1 foliations (S1) and stretching lineations associated with D2. 1% area contour lines used.

27 4.1.4. Main Range Granites

Within the Main Range granites, deformation is localized in shear zones that vary in width from centimetres to 10s of metres (e.g. fig. 21A and 21B). Grain size in these zones is strongly reduced and shear planes are often associated with localized chlorite growth and quartz veins. Overall, the granites display very steep foliation planes (fig. 23). Because the deformation causing these steep foliation planes in the Main Range Granites (west of Bentong-Raub) is thought to have occurred post-intrusion, it is considered to postdate deformation phase D2. Also, different orientations and movements of shear zones as well as the lack of two dominant folded foliations within the granites indicate that the deformation in the granites must be considered a different event/phase: D3.

A B Fig 21 Field photographs of Main Range grante outcrops. Figure A shows a sheared clast within a shear zone, figure B shows a strongly foliated granite (parallel to the joint crosscutting the outcrop); outcrop 2.1 (photographs by Dr Thomas François)

Two types of shears were observed within the granite intrusions. One set of shears shows steeply plunging stretching lineations along almost vertical foliation planes showing normal shear. In other locations strike-slip movement along shallow plunging stretching lineations on steep foliation planes were observed. This variation in shear sense and stretching lineation is also recognized in two major fault zones within which most deformation is localized: the Bukit Tinggi and the Kuala Lumpur fault zone (see fig 22).

28 Fig. 22 Map view of the locations of and shear senses along the Bukit Tinggi Fault Zone (BT), and the Kuala Lumpur Fault Zone (KL) (Adapted from Morley, 2012).

Fig. 23 Stereographic projections incorporating all foliations and stretching lineations in the Main Range granites (D3 & D4). Red triangles are strike-slip stretching lineations in the BT Fault Zone; black dots are in KL Fault Zone (D4). Normal shears only in Bukit Tinggi (D3). 1% area contour lines used.

In the Bukit Tinggi fault zone, some variation in the type- and direction of movement along the foliation planes is observed. Top E movement on E-dipping foliation planes is observed in one case. In another location, normal movement is also observed but on W-dipping planes with SW-plunging stretching lineations (i.e. top to SW). Shears are distributed in a NE-SW direction in stereographic projection (fig. 23). Despite the discrepancies in the movement along foliation planes, it is clear that the movement is vertical, and dominantly has a normal sense. This shearing is also considered to be part of deformation phase D3. Shearing associated with the Kuala Lumpur fault zone (see fig. 23) is generally NW-SE oriented. Thrust movements on steeply dipping planes are observed, showing top to SE movement. Also, both sinistral and dextral strike-slip shearing is often observed which is similar in sense and orientation to the shear sense recorded along L2 stretching lineations in the meta-sediments. Some strike-slip shear is also observed along the Bukit Tinggi Fault Zone (see red triangles in fig. 23) It seems that this strike-slip shear is reflected in all lithologies in the study area, implying that it postdates all previously described structures. This deformation phase D4 thus causes dominantly NW-SE oriented strike-slip shear along existing foliation planes throughout the study area.

29 4.1.5. Kinematics

The figures below represent the kinematics of the study area. . Arrows, representing stretching lineations, have been given different colours based on the deformation phase (D1-D4) they are associated with. Figure 24 shows an overview of all stretching lineations measured in the study area, separated by the lithology in which they were measured. Figure 25 displays shear senses along measured stretching lineations in which the arrow points in the direction of (top to) movement. Some stretching lineations have similar orientations to others which have been ascribed to other deformation phases. Due to timing of the different deformation phases as well as differences in shear sense (normal, reverse and strike-slip), these similarly oriented lineations cannot be considered to represent coeval movement.

Fig. 24 All stretching lineations without shear sense criteria. D1 – L1 lineations on S1 foliation planes are black; D2 – Triassic stretching lineations are blue; D4 – L2 lineations are shown in red. Green arrows are all stretching lineations measured in the Main Range Granites, some of which belong to D3 and some of which are D4.

30

Fig. 25 Shear senses of each deformation phase. Arrows point in the direction of movement. L1 shears on S1 foliation planes, D1 (black); shears in Triassic rocks (blue, D2); normal shears in granites (green, D3, dotted arrows are unsure); strike-slip shears in granites and L2 stretching lineations on S2 foliation planes, all part of D4 (red).

31 4.2. Thin section and SEM analysis

Oriented samples have been taken from all units of the study area, to gather kinematic information and to determine the metamorphic grade of the different lithologies. The localities at which rocks were sampled are shown in figure 26. Overview scans of the thin sections are given in appendix 2.

Fig. 26 Sample locations (purple) and sample numbers

32 4.2.1. Metasediments

Most fine-grained rocks sampled from the Bentong-Raub zone are sediments, either radiolarian or sandstone, and thus were not useful for metamorphic and kinematic analysis. However, the samples that were taken near to the serpentinite outcrop on the road from Sungai Kayan to the Cameron Highlands show interesting assemblages. Sample M15 is rich in (ortho-)pyroxene, olivine, serpentine, chlorite, feldspar, hornblende, biotite, and zoisite (see appendix 3 and fig. 27).

Sample M24 is a dolerite/olivine-diabase containing olivine, serpentine, clino-pyroxene, plagioclase & segregations of something possibly titanium rich (Fig. 27). It is probable that the outcrop from which this sample was taken is the host-rock from which the serpentinites were derived. SEM analyses were done to determine mineral compositions within these samples, in order to gain more information on the origin of these rocks. SEM analyses did, however, not yield very precise results (e.g. all measurements show an excess in Si. The tables with the measured assemblages are given in appendix 3. Samples M15 and M24 were analysed at various locations within the thin section in order to get an idea of the mineral assemblage of each of the samples. SEM analyses of sample M15 showed the following mineral assemblage: ilmenite, copper ferric sulphide, albite, apatite, diopside, epidote, chlorite, quartz, titanite and K-feldspar. This presence of chlorite and epidote might indicate metamorphism at greenschist facies conditions, which is comparable to the meta-sediments in the surrounding lithologies In sample M24, spot analyses yielded mineral assemblages resembling minerals such as albite, pyroxene, K-feldspar, olivine, sphalerite, ferrous sulphide and quartz.

A B Fig. 27 Part of thin sections of samples M15 (A) and M24 (B), cross polarized light, optical microscope

33 Most Ordovician-Silurian samples are schists of which the grain size was too small to determine the shear sense in the field. Sample M1 represents a fairly common lithology of strongly foliated ‘massive’ rock, which is dominantly rich in biotite, amphibole (actinolite), clinozoisite, feldspars (Carlsbad twins) and quartz. The bedding in this rock is strongly crenulated and a crenulation cleavage is seen. Without further knowledge of the type of feldspar in this rock (albite or oligoclase) not much can be said about the metamorphic grade. The location from which this rock was sampled is quite adjacent to the Main Range granite intrusion. Most probably the heat of this intrusion caused the originally schistose rock to harden and allowed the growth of e.g. actinolite and clinozoisite. Although the rock is very fine-grained, some asymmetric clasts/ quartz-rich mineral aggregates, such as the one shown in figure 28, are indicative of a top to SE shear sense.

Fig. 28 Asymmetric clast/mineral aggregate showing shear sense (green arrows); Surrounding foliation is S1; sample M1

Sample M3 represents a similar lithology to the outcrop from which sample M1 was taken. The thin section shows very fine grained recrystallized quartz, chlorite and white mica, implying greenschist facies metamorphism. The general fabric that is observed is characterized by elongated chlorite grains, and a tightly folded white mica is also observed.

Sample M9 portrays spaced S2 foliation and isoclinally folded S1 within a typical Ordovician-Silurian schist (see figure 29A). The sample consists mainly of a white mica and quartz , but some chlorite domains are seen also, as well as tourmaline (see figure 29B) and some weathered minerals of which the composition is unclear. What is most interesting about these weathered minerals is that they portray an internal folded foliation (see figure 29C). The chlorite domains also represent both isoclinally folded S1 and axial plane foliation S2, implying that greenschist facies metamorphism was reached pre-S1. Backscatter imaging (fig. 29D) in the table-top SEM showed that the weathered mineral displaying internal foliation (labelled as S2, folded blue line) in sample M9, is made up of many fine-grained minerals such as quartz and Ti- and Cl- exsolutions. The mineral assemblage of this heterogeneous cluster can thus not be determined exactly. The cluster does not consist of a single, dominant mineral assemblage, as was expected.

34 A B

C D Fig. 29 A) Photograph of isoclinally folded micas in M9, plain polarised light (PPL); B) Tourmaline crystals in mica layers, M9 (PPL); C) Weathered mineral with internal S2 foliation showing syn-tectonic rotation in sample M9. S1 is not visible in this photograph (PPL); D) Backscatter image of ‘weathered’ mineral in sample M9

Samples M11 and M12 are almost entirely made up of fine-grained amphibole, though some quartz (veins), chlorite and feldspar (Carlsbad twins) are seen as well. Perhaps these samples, from an Ordovician-Silurian outcrop in the middle of the Main Range Granite, represent the highest grade of metamorphism in this area.

The thin section of sample M23 consists of two domains. One part of the thin section clearly shows two foliations as well as isoclinally folded quartz veins which are displaced by S2 (figure 30). The other part of the thin section portrays only one foliation which is at an angle to both foliations in the other domain. It cannot be said whether this foliation represents a third foliation or if the difference in orientation between the foliations is due to refraction due to a difference in competence between the two domains. A west-block to NW shear sense is observed on S2 planes.

35

Fig. 30 Displacement of quartz veins by shear along S2 foliation planes in sample M23

Sample M27 comes from a phyllite outcrop which clearly showed two foliations of which S2 was the axial plane foliation of isoclinally folded S1. In the field S2 was also observed to be openly folded. In thin section the sample portrays a single foliation defined by very fine-grained quartz and muscovite minerals, which is affected by a secondary deformation structure which crosscuts the dominant foliation at an angle. Quartz veins are also present. Besides quartz and white mica, some small tourmaline crystals are observed. The overall mineralogy of this sample implies that metamorphism occurred under greenschist facies conditions.

The sample from the Devonian outcrop west of Kuala Lumpur/west of the Main Range granite, M26, clearly displays two foliations. The rock is made up entirely of quartz and white mica. Larger quartz grains are clearly sheared by the S2 foliation and show top to W shear (see figures 31 and 32).

Fig. 31 Cross-cutting relation between S1 and S2 Fig. 32 Shear sense indicators: quartz crystals are foliation, sample M26 sheared by S2 foliation, sample M26

36 4.2.2. Granites Three thin sections were made of granite samples. Two of these samples are oriented and come from shear zones related to the Bukit Tinggi fault zone (M2) and the Kuala Lumpur fault zone (M13). The third sample is from a fine-grained granite outcrop along the highway from Kuala Lumpur to Bentong that was determined to be undeformed in the field.

The granites all have a composition of quartz, feldspar, white mica and amphibole. Recrystallization of quartz is observed in samples M2 and M13, and is probably due to subgrain rotation (i.e. at 400-500 °C). Sample M2 also contains some minor biotite, and some feldspars are clearly folded (see figure 33A). Shear senses are observed with more difficulty in thin section than in the field. Figure 33B shows a possible shear sense indicator made up of two feldspar crystals which seem to have been sheared showing a reverse movement to SE.

A B Fig. 33 A) Deformed feldspar crystal in quartz domain, sample M2; B) Displaced feldspar, sample M13

The most striking feature in the thin section of the seemingly undeformed granite sample M28 is a single amphibole crystal which shows strong folding and might display two foliation phases (fig. 34).

A B Fig. 34 Deformed amphibole crystal; A) overview photograph; B) detailed photograph showing folding of ‘S1’ into ‘S2’, sample M28

37 4.2.3. Shear senses

An overview of the shear senses observed in thin section is given in table 2.

Foliation along Shear sense thin Sample no. Lithotectonic unit Shear sense field which shear is section observed Ordovician-Silurian Top up, to 159 Top to 159 S1 or S0?? M1 (OSE) Granite (GSW) Top down, to 208 If amph is c-axis  S1 M2 top up; if sigma-clast  top down Ordovician-Silurian ? Very unclear, S1 M3 (OSE) perhaps top down, to 260? M9 Ordovician-Silurian Top down?, to 156 Top down, to 156 S2 Ordovician-Silurian Top down, to 256 S1 M11 & M12 (M11), top up to 76 M12? Granite (GSW) Might be top up, to Top up(?)To 154 S1 M13 154 M15 Basic intrusion - - M16 Bentong-Raub - - M20 Bentong-Raub ? - - M21 Bentong-Raub ? - - M22 Bentong-Raub ? - - Ordovician-Silurian Top down, to 312 S2 (not observed M23 in field) M25 Ordovician-Silurian ? S1 M26 Devonian Down, to 260?? Top down, to 260 S2 Ordovician-Silurian Top up, to 356 Top up, to 356 S1?? M27 (OSW)

Table 2 Shear senses observed in samples. Both shear senses in the outcrop and in thin section are noted.

38 5. DISCUSSION

In this research, a detailed study of the deformational and lithological features of the Bentong- Raub Zone and its relationship with the surrounding rocks was conducted in a 180x120 km large study area surrounding Kuala Lumpur. A large study area was necessary to gather sufficient data to create a more complete understanding of the origin of the Bentong-Raub Zone, its emplacement within Peninsular Malaysia and its exhumation.

5.1. Interpretation of field & thin-section analysis

Structural and kinematic field data showed that various deformation phases/structures have affected the numerous lithological units surrounding Kuala Lumpur. Of the various lithological units that were recognized in the field the Ordovician-Silurian, Devonian and Bentong-Raub units/zones, show the clearest definition of two foliations S1 and S2. Bedding planes are less clearly observed in these lithologies: as intercalations of black and white chert in the Bentong-Raub Zone and quartz- and mica-layers in schists of Ordovician-Silurian and Devonian age. Triassic sediments east of the Bentong-Raub Zone display a single axial plane foliation of asymmetrically folded bedding planes. Main Range granites show localized deformation and the development of a single foliation.

Deposition of Ordovician-Silurian to Devonian quartz-mica schists and slates (including Bentong-Raub) presumably occurred in marine environmental settings. The abundant cherts of the Bentong-Raub zone imply a deeper marine depositional setting. Metamorphic conditions in these lithologies do not exceed greenschist facies conditions. In one outcrop of Ordovician-Silurian rocks in the centre of the Main Range Granites, thin section analysis revealed a high abundance of very fine-grained amphibole. Most probably, these amphibole crystals grew as a result of the increased temperature due to granite intrusion. Undeformed micro-tourmaline probably crystallized from fluids during a late thermic event, possibly also related to the granite intrusion. Besides these tourmaline crystals, no minerals were seen overgrowing S2 foliation, implying that peak metamorphic conditions were reached pre-S2. On a regional scale, it appears that metamorphism increases in grade towards the east: garnet- graphite schists and biotite schists are only observed east of the Main Range granites. West of the intrusion only muscovite-chlorite phyllites are found. This metamorphic gradient implies that more exhumation and subduction occurred towards the Bentong-Raub Zone. This idea is supported by the presence of serpentinite, and the characteristic chert-pyroclast rocks which resemble a tectonic mélange, which imply that (part of) the Bentong-Raub Zone is an ophiolitic mélange.

The best defined planar feature in the Bentong-Raub, Ordovician-Silurian and Devonian lithologies is a foliation S1, interpreted to be approximately parallel to bedding planes S0. Alexander (1968) and Shuib (2009) also record foliation parallel to bedding. Isoclinal folding of S1 is commonly observed, yet data of the implied isoclinal folding of S0 bedding planes is lacking. An axial plane foliation S2 of the isoclinally folded S1 foliation also folds along steeply dipping axial planes, often observed as refolded isoclinal S1 folds by open folds. Coeval with this open-style folding, shearing occurred along S1 foliation planes. This is supported by the inconclusive shear senses and stretching lineations observed in the field. These deformation structures in the meta-sediments of the Bentong-Raub, Ordovician- Silurian and Devonian units all show an overall NE-SW shortening direction, and the

39 protoliths of the metamorphic rocks imply a similar depositional environment. Therefore, they are interpreted to be part of a single progressive deformation phase, D1. The high extent of folding and faulting especially observed in the Devonian outcrops west of Kuala Lumpur imply that deformation most likely occurred in an accretionary wedge. This relates deformation phase D1 to the ongoing northward subduction of the Paleo-Tethys Ocean beneath Indochina during Triassic times (see fig. 4, Hutchison, 2007). The minor thrust faulting observed in the Devonian outcrops clearly overprints the foliation (S1). However, the orientation of this brittle deformation is still similar and is therefore regarded as a late stage effect of the progressive deformation. Since no major faults or L1 shears were observed within the Ordovician-Silurian and Devonian outcrops west of the Main Range Granites, it is assumed that these lithologies are part of a single tectonic sliver, or nappe, in the accretionary wedge system. The observation of L1 shear increases in frequency towards the east and it is therefore thought that a tectonic contact lies between the Ordovician-Silurian outcrops and the Bentong-Raub zone. This idea is supported by the lack of Ordovician-Silurian and Devonian outcrops west of Bentong-Raub zone (i.e. a separate nappe), implying that the Ordovician-Silurian (now thought to be sub- surface) was overthrust by the Bentong-Raub zone.

A second deformation phase, D2, is regarded as the deformation within the Triassic (meta-) sediments. These Central Belt rocks were deposited after or synchronous to the formation of the accretionary wedge complex, and probably exist of forearc basin deposits, which were subsequently asymmetrically folded (W-vergence) and foliated by an axial plane foliation. Although the shortening direction of this deformation phase is also NE-SW, it is regarded a separate event due to the fact that the associated structures are only observed within the (Permo-)Triassic unit.

Intrusion of the Main Range Granites occurred during Triassic – Jurassic times (Hutchison, 2007), meaning that the localized NE-SW (shortening direction) deformation in shear zones must have occurred during a later stage. The steepness of the foliation and shear zones observed in the granites does not coincide with any of the deformation styles in surrounding lithologies. In contrary to deformation in the Triassic (meta-)sediments, this deformation phase (D3) is considered to post-date the intrusion of the granites at 251-254 Ma (Krähenbuhl, 1991). The strongly foliated and crenulated amphibole crystal in the supposedly undeformed granite sample (thin section M28) most likely implies that it is a xenocryst from deeper sediments that have undergone higher grade metamorphism and which then mixed with the granitic melt during intrusion. Another explanation would be that the granite intrusion was simultaneously folded and foliated with the surrounding sediments. If this would be the case, granite intrusion should have occurred pre-accretionary wedge formation and this was not the case.

Shallow-dipping dextral strike-slip shearing on S2 foliation planes is observed throughout Ordovician-Silurian, Devonian and Bentong-Raub zone outcrops within the area. Also, strike- slip shears are also expressed in some locations of the Main Range Granites. Most likely, the S2 shear is related to extension in NW-SE direction, and to exhumation. The orientation of this dextral strike-slip shear shows dominantly NW-SE stretching. However, its timing, relative to the deformation in the surrounding lithologies remains unconstrained. Because this deformation, in contrast to others, is observed throughout all lithologies, it is interpreted that it post-dates phases D1-D3, and it is therefore referred to as D4.

40 The opening of extensional basins surrounding Peninsular Malaysia is thought to have occurred in Cenozoic times, either due to pull-apart strike-slip deformation or due to slab roll- back of the subducting plate. If it is assumed that dextral strike-slip shearing associated with L2 stretching lineations occurred coeval to the formation of these extensional basins, this deformation event must post-date both deformation in the Main Range granites (D3) and in the Triassic (meta-) sediments (D2). The dextral shear recorded in the Bentong-Raub Zone, Western- and Central Belt implies a switch from dominantly compressional NE-SW deformation, as a result of perpendicular subduction, to oblique subduction (Hutchison, 2007). Strain partitioning subsequently caused the development of dextral strike-slip shear throughout the western part of Peninsular Malaysia.

Hutchison (2007) describes well displayed NW-SE trending faults throughout Peninsular Malaysia, dominantly observed in granitic rocks. It is suggested that the discrepancy between the lithologies on either side of the Bukit Tinggi Fault, i.e. Main Range granite in NE, and metasediments in SW, indicates a major downthrow of over 1.5 km towards the SW. This is in line with some observations done in this research within the Main Range granites (D3). More specifically, it is obvious that stretching lineations along the Bukit Tinggi Fault Zone plunge NE and SW. Several faults parallel to the Bukit Tinggi Fault also progressively downthrow the Main Range granites to the SW. It is also reported that the extension related to the formation of these faults might be related to the formation of Tertiary basins in Peninsular Malaysia (Hutchison, 2007). If this were true, the exhumation of the Main Range Granites by normal faulting associated with the Bukit Tinggi Fault, could be considered to be simultaneous to the dominantly dextral shear of deformation phase D4. However, stretching lineations formed during D4 are generally NW and SE plunging. Stretching lineations along the Bukit Tinggi Fault Zone were clearly NE and SW plunging, indicating a different stress field. Possibly, the Bukit Tinggi-parallel faults are associated to the earlier deformation phase D3, showing steep normal shear in the granites, and NW-SE strike-slip shears belong to the larger-scale D4 deformation phase. Nevertheless, both structures could have played a major role in the exhumation of the study area.

The thermochronology of the Main Range Granites has been studied extensively by a.o. Cottam et al. (2013), by 40Ar/39Ar and zircon and apatite (U–Th–Sm)/He dating (fig. 36). This study shows that e humation of the Main ange occurred rapidly and closure temperatures of 183°C were reached in Late Cretaceous – Early Paleogene times. Fission track ages (205°C closure temperature) by Krähenbuhl (1991) also yielded Early and Late Cretaceous ages for zircon crystals (circled in red, fig. 35A). Although different exhumation rates and ages were interpreted for different samples in the Cameron Highlands, Cottam et al. (2013) conclude that widespread regional uplift took place during Cretaceous and Early Cenozoic times. Apatite dating (both (U–Th–Sm)/He and fission tracks by Krähenbuhl, (1991) indicated rapid exhumation in Late Eocene – Oligocene (circled in blue, fig 35A). Cottam et al. (2013) (as well as e.g. Hall, 2002) also propose that cessation and subsequent resumption of subduction along the southern Sundaland margin occurred due to the presence of a subducting microplate. Then, resumption of this subduction would have reversed the reported dynamic topographic low and onset the process of uplift and exhumation, also allowing the influx of hot asthenosphere under the thin crust. Krähenbuhl (1991) proposes thrust faulting and overthrusting of slabs to cause high vertical block displacement (exhumation) as the reason for highly variable K-Ar biotite ages, possibly postdated by brittle NW-SE trending strike-slip

41 movements. His data also indicates uniform uplift of the Main Range Granites in Oligocene – Miocene times. It is suggested that the rapid exhumation interpreted by Cottam et al. (2013) was coeval to offshore subsidence (i.e. the opening of extensional basins described above). This conclusion is in line with the regional strike-slip shearing observed in this study, which is also interpreted to be coeval to offshore basin formation. Dextral strike-slip as a mechanism for exhumation during Paleogene times is also proposed by Morley (2012) (see fig. 35B).

Figure 36 shows a summary of mainly the Late Cretaceous and Cenozoic events described by Cottam et al. (2013) and in previous research, and includes the deformation phases interpreted in this research2. The observations made here are also shown in table 3, along with their associated processes and the timing of the formation of the various structures.

A B Fig. 35 A) Zircon and apatite fission track dates by Krähenbuhl (1991), zircon ages are circled red, apatite ages are circled blue. B) Dextral strike-slip shear in Peninsular Malaysia affected by Paleogene exhumation during transpressional/compressional deformation (Morley, 2012).

2 Fig. 36 (next page) Summary of tectonic events and their timing interpreted by Cottam et al. (2013) (first column) and previous authors (second column), including the interpreted deformation phases in this research shown in the third column (adapted from Cottam et al., 2013).

42

43 Process at Timing Ordovician- Devonian Bentong-Raub Triassic Granites play Silurian

Accretionary wedge formation and associated D1 deformation in nappe stacks.

Upper Permian – & Burial Lower Triassic

Greenschist facies metamorphism associated with burial M1 of ocean floor sediments. Eastern sediments were buried deeper and thrust up during plate convergence.

Deformation in fore-arc D2 basin related to plate

convergence. & Burial Upper Triassic

Burial of basin M2 sediments.

Granite intrusion (M3) Intrusion Upper Triassic

Contact Metamorphism D3 Extension/steep normal faulting Cretaceous - Paleogene NW-SE strike-slip shearing D4 Exhumation Normal faulting (Hutchison, 2007)

Table 3 Observed structures interpreted as processes and linked to the lithological unit in which they were observed, as well as their relative timing.

44 5.2. Cross section

A cross section was developed taking into account the compressional deformation history (D1-D3) of the study area. Shear planes of deformation phase D4 (red pins) are incorporated as well.

Firstly, an axial plane of S2 folds was extrapolated to the entire section, from which open folding of S2 was interpreted for the Ordovician-Silurian and Devonian meta-sediments. In the field, isoclinal recumbent S1 folding is observed of which S2 is the axial plane. Thus, the interpretation of S2 open folds was used in combination with S1 foliation plane measurements to attempt an interpretation of the geometry of these isoclinal recumbent folds. Only in locations where S1 measurements were taken, could the geometry of the isoclinal recumbent folds be interpreted. Close-ups of the S2 large-scale folding show the resulting geometry of these primary folds. D1 shear planes in the Western Belt are given as black pins.

Asymmetric W-vergent folds with S1 as their axial plane foliation were seen affecting bedding planes in Triassic outcrops east of the Bentong-Raub zone. The cross section shows the difference of fold geometry and vergence to those observed in the western metasediments. Intrusion of the Main Range Granites has also been interpreted to be post-D1, and the granite is not affected by the large-scale folding. Because the shear zones in Triassic (D2) and granitic outcrops (D3) are ascribed to different deformation phases, they have been indicated separately, by orange and green pins, respectively.

Ordovician-Silurian and Devonian lithologies are most evident west of the Main Range granite intrusion. East of the granites, the Ordovician-Silurian unit is in contact with the Bentong-Raub zone, and the Devonian unit is absent from map view. This suggests a tectonic contact between the Bentong-Raub Zone and the Ordovician-Silurian and Devonian metasediments. The low topography seen in the field and on the map (overlain by the road between Bentong and Raub) does not contradict this theory. Two dominant thrust movements were interpreted from the Bentong-Raub outcrops, comprising a SW-block to ESE movement within the cherts and a NE-block (conglomerates) to WNW (cherts) movement. As the relative timing of these shears is not entirely clear, two interpretations of the large-scale structures are suggested. Uncertainties in these two cross section also lie (a.o.) in the thickness of (meta-) sedimentary deposits and the sub-surface/sub- Ordovician-Silurian lithologies (here suggested to represent Pre-Palaeozoic basement).

Both these interpretations however imply thrusting of young rock in the hanging wall (Triassic) over older rock (Bentong-Raub & metasediments). To initially get the differently aged rocks at the same topographic level, however, the younger rock must have been downthrown by normal faulting prior to thrusting. This normal faulting was not observed clearly in the field, however it might be overprinted by the reverse movements now seen.

45 Cross section A (fig. 37) suggests that deformation occurred in an accretionary wedge environment, causing the development of SW-vergent fold- and fault structures. It is interpreted that SW-dipping backthrusts developed in the Bentong-Raub Zone after the formation of some major NE-dipping thrust faults bounding the different nappes within the accretionary wedge. Because the conglomerates are assumed to be of a younger age than the Bentong-Raub cherts (as recorded by Shuib, 2009), the NE-dipping thrust fault probably represents the youngest structure. Then, the SW-dipping backthrusts would have been displaced by, for example, the reactivation of an older thrust.

Figure 38 shows the large-scale step-by-step and in-depth interpretation of this model.

Fig. 37 Cross section A; interpreted large-scale structures from measurements in the field. For location see fig. 5; 8x times vertical exaggeration

46

A f B

Fig. 38 Conceptual step-by-step evolution model of cross section A set in the large scale subduction setting (not to scale), showing an initial forward-breaking fault system (A), followed by the development of two backthrusts (B) and reactivation of a foreward- breaking thrust displacing the two backthrusts (C). Dotted red lines indicate unknown, implied fault paths C

47 Cross section B (fig. 39) is an alternative interpretation of cross section A. The major point of discussion being the tectonic contact between the Bentong-Raub zone and its surrounding units. The structures interpreted in this cross section also suggest initial development of large-scale NE-dipping thrusts, with the entire Bentong-Raub zone acting as a single block or nappe, being thrust over the Ordovician-Silurian and Devonian rocks. Subsequent shallow backthrusting displaces part of this overlying nappe, removing the overlying Devonian metasediments. Figure 40 shows the large-scale (and in-depth) interpretation of this model and its development over time.

Fig. 39 Cross section B; interpreted large-scale structures from measurements in the field. For location see fig. 5; 8x times vertical exaggeration

48

A B

Fig. 40 Conceptual step-by-step evolution model of cross section B set in the large scale subduction setting (not to scale), showing an initial large-scale shear zone thrusting up the Bentong-Raub zone (A), followed by the upthrusting of the Ordovician-Silurian-Devonian nappe (B) and the development of a backthrust which displaces the primary shear zone and which cross-cuts the Bentong-Raub Zone (C). C Dotted red lines indicate unknown, implied fault paths

49 Important to note is that the open folds affecting the S2 foliation planes in the accretionary wedge sediments (shown in both cross sections above) have a slight eastward vergence. This does not correlate to an expected westward transport direction in an eastward moving subduction setting. It is assumed that during formation of the accretionary wedge, the upright, symmetrical open folds in these metasediments might have been slightly W-vergent, and that tilting by developing thrust faults occurred at a later point. Because the folds in the Triassic sediments east of the Bentong-Raub zone do still show a W-vergent geometry, tilting of the older rocks must have occurred prior to deposition of Triassic sediments (pre-D2). Most probably, tilting occurred due to upward thrusting of the Ordovician-Silurian nappe during the formation of one of the later (most west-lying) faults during accretionary wedge formation (see most west-lying faults in fig. 37 and 39). This could have caused the axial plane of these symmetrical folds to steepen and eventually overturn to dip towards the west.

Although both cross section models described above seem plausible, the dominance of SW- dipping thrust planes within the Bentong-Raub Zone implies that backthrusting was of major importance within this zone. Also, the timing of faults, i.e. the fault thrusting conglomerate over chert being younger than fault within the chert, leads to a preference of cross section A over B.

50 5.3. Tectonic implications

The structural and metamorphic field observations in the study area are better understood when put in the context of the tectonic setting of the colliding Sibumasu and Indochina terranes. A timeline of deformational events is shown in figure 42.

The separation of Indochina from Gondwana in Late Carboniferous times and the coeval formation of the Sukhothai Island Arc, are taken to represent the primary tectonic activity within the proposed tectonic model (fig 42). As a result of this rifting phase, the Paleo-Tethys Ocean opened. Ordovician-Silurian sediments were deposited on the newly-formed marine basin floor, and were gradually overlain by sediments of Devonian age. Middle Devonian – Early Permian rifting between Sibumasu and Australia/Gondwana subsequently occurred and Sibumasu moved eastward (Hutchison, 2007). Narrowing of the Paleo-Tethys occurred from Middle Permian to Upper Triassic times (Hutchison, 2007), and consecutive formation of an accretionary wedge at the boundary between the Paleo-Tethys and Indochina followed. Due to the NE-SW oriented closure of the Paleo-Tethys Ocean, folding and faulting in the accretionary wedge sediments intensified, causing deformation phase D1: the formation of the S1 foliation and its isoclinal folding into axial plane cleavage S2. Associated with these structural features is the greenschist facies metamorphism related to the burial of the sediments (M1). The soft-sediment structures observed in the Bentong-Raub cherts imply that some shortening must have occurred shortly after the deposition of these sediments. Burial of the affected Ordovician-Silurian and Devonian sediments also plays an important role in the formation of the folding structures observed throughout the meta-sediments. Faults and folds within the accretionary wedge are expected to have had a westward transport direction/eastward dip. Continental collision between Sibumasu and Indochina finally ensued in Upper Triassic times, and was associated with severe deformation. As a result of this collision, the axial plane cleavage S2 (of the burial folds of S1), was folded by NE-SW shortening and resulted in an open-style set of folds. The stress field necessary to refold the isoclinally folded S1 foliation must have been slightly different to the orientation it had during isoclinal folding, in order to create the resulting structures. Stretching lineations on S1 foliation planes dip NW and SE, and possibly, a conjugate set of NE-SW oriented lineations was also measured. These orientations are in line with the convergent setting of Sibumasu and Indochina and thus are interpreted to have formed and been active either coeval with folding of S1 foliation planes or with S2 planes. These stretching lineations are also interpreted as part of the same progressive deformation event D1.

Deposition of Triassic sediments probably occurred in a forearc basin related to the formation of the accretionary wedge and further closure of the Paleo-Tethys Ocean (Hutchison, 2007). Subsequent deformation and very low grade metamorphism (M2) localizes in these sediments and postdates the D1 deformation in the Western Belt. Therefore, this deformation is regarded as a separate deformation phase D2.

It remains unclear what caused the melt generation necessary for the intrusion of the Main Range Granites. Hutchison (2007) suggests, that due to heating of the deeply buried sediments at the bottom of the nappe stack (accretionary wedge), melt formation occurred and resulted in the intrusion of the Main Range S-type granites within the overlying sediments. The abnormally high uranium and thorium numbers shown by Cobbing et al. (1986) and Liew

51 (1983), support this. On the other hand, the onset of, for example, delamination or slab break- off (Metcalfe, 2013), could have created an opening between the two converging plates, allowing hot asthenosphere to be wedged in and melt the overlying crust (dotted pink arrows in fig. 42). These latter options would explain why the crust beneath Western Malaysia is thin (<20 km) (Ryall, 1982 and Hutchison, 2007). It must however be noted that no relicts or evidence of molten asthenosphere is seen throughout the study area.

Although contact metamorphism (M3) is observed in some localities (e.g. fine-grained amphiboles in samples M11 & M12), it is not extremely pervasive. This might be explained by the high temperature of the surrounding sediments as a result of their burial in the accretionary wedge. Volcanism in the Central and Eastern Belts has been recorded (Hutchison, 2007) and might have occurred as a result of the collision of the two continental terranes as well.

Large-scale rapid exhumation of the Main Range granites and the surrounding sediments is thought to have occurred either as a fairly late-stage effect (Eocene – Oligocene, Cottam et al., 2013 and Krähenbuhl, 1991) of the collision between India and Tibet, or due to resumption of subduction after microplate collision. Due to collision of India and Eurasia in Cretaceous times, clockwise rotation (Hutchison, 2007) of SE Asia occurred, resulting in major NW-SE oriented strike-slip faults/shears such as the Red River Fault Zone. Non- uniform NW-SE sinistral shear displacement is thought to represent the early syn-rift phase of the Malay Basin. As the East Malaya Block became adjacent to Indochina in Eocene times, movement towards the SE slowed, resulting in the reversal of sinistral shear to dextral NW- SE shear (Mansor et al., 2014). Consequently, the Malay Basin opened further and, presumably, exhumation in the Indochina-adjacent Sibumasu terrane occurred as well. Most likely, the localized strike-slip shears within the Main Range Granites are associated with this large-scale dextral strike-slip (NE-block to SE) movement, here referred to as deformation phase D4. This deformation perturbates all lithologies, although its structural expression varies. Steep normal faulting along and parallel to the Bukit Tinggi Fault Zone within the Main Range Granite (D3) is interpreted to also be associated with the exhumation of the granites.

Figure 41 shows an example of two observed dextral strike-slip shear zones (red) in Ordovician-Silurian outcrops on either side of the Main Range Granites. Possibly, the interpreted step-faults (blue) that link these two faults, then represent normal faults downthrowing rock in both NW and SE directions (blue arrows). In some locations such orientations of faults were indeed measured (fig 21&22).

Fig. 41 Sub-parallel dextral shears (red) creating a step- over (blue) and causing extension in the intermediate area (here: Main Range Granite). The blue dotted lines then represent the strikes of normal faults, downthrowing rock in the direction of the blue arrows.

52 Shearing within the Main Range Granites probably represents both D3 and D4 deformation phases: the Kuala Lumpur Fault Zone strike-slip shears could very well be ascribed to D4 strike-slip. The steep normal shears along the foliation planes in the Bukit Tinggi fault zone, however, are oriented in an opposite direction and therefore might be part of the normal faulting described by Hutchison (2007) and responsible for large-scale exhumation. It is very well possible that deformation phases D3 and D4 are related, and that exhumation by normal faulting was accommodated by strike-slip shearing, or vice versa.

Fig. 42 Tectonic model including the timing of tectonic events relevant to the geology in western Malaysia. See text for explanation.

53 5.4. Is Bentong-Raub a suture?

One of the main aims of this research was to determine whether the Bentong-Raub zone is indeed a suture, as is strongly suggested by (a.o.) Metcalfe (2013). Tan and Khoo (1981) suggested that insufficient evidence was available to draw this conclusion, as insufficient features related to ophiolitic belts have been observed. Within the Bentong-Raub Zone, ribbon cherts, shallow marine deposits (now greenschist facies schists), tectonic mélange (pyroclastics + chert), dolerite and serpentinite bodies have been observed. SEM analyses of the probable serpentinite-protoliths did not yield conclusive evidence for ancient oceanic lithosphere. The interpreted mechanism of nappe stacking and the collision of two continental terranes subsequent to the subduction of the Paleo-Tethys Ocean, implies that an ophiolite could be present within the study area. Possibly, the ‘slice’ of oceanic lithosphere that was thrust upward is now part of the accretionary wedge system of the Western Belt, which underwent complex multi-stage deformation. The effect of the progressive deformation that accompanied the accretion of Sibumasu and Indochina, might have attributed to the lack of a total ophiolite in the Bentong-Raub Zone. However, the abundant tectonic mélange and chert outcrops in combination with the dolerite and serpentinite bodies, do imply strongly that oceanic lithosphere was (partially) obducted. Therefore, although substantial evidence is still lacking, the Bentong-Raub is interpreted to be (part of) a suture (i.e. the ophiolitic mélange), rather than a fault zone representing the western boundary of the Central Belt (Tan, 1984). Nevertheless, a solution has yet to be found for problems such as the lack of ultrahigh pressure metamorphics (UHP).

54 6. CONCLUSIONS

A detailed structural and kinematic study was conducted in the Bentong-Raub Zone, Western- and Central Belts of Peninsular Malaysia. Although a fair amount of research has been done in SE Asia, many questions have remained unanswered about the geology of Peninsular Malaysia. This research has been conducted with the aim to determine the origin and late- stage deformation of the Bentong-Raub Zone (a suture?), its relation to the surrounding lithologies, and to develop a tectonic model which fits the structural, metamorphic and kinematic data gathered in the field.

A tectonic model has been proposed that explains most deformation structures observed in western Peninsular Malaysia. Set in a convergent plate setting between Sibumasu (west) and Indochina (east), accretionary wedge formation of Paleo-Tethys ocean sediments and subsequent isoclinal folding of S1 foliations occurred. Further closure of the Paleo-Tethys caused the folding of S2 foliation planes (axial plane of S1 isoclinal folds), and coeval shear along L1 stretching lineations.

Throughout the study area at least four deformation phases have been recognised. The most dominant phase being the formation of the oldest structures related to progressive deformation in an accretionary wedge setting, associated with the collisional/subduction setting of the Sibumasu Terrane and the Indochina Block. This primary deformation phase, D1, is defined clearly in the meta-sediments of the Devonian, Ordovician-Silurian units and the Bentong-Raub zone, and it comprises most deformation structures within these units. NE-SW shortening direction caused the formation of two foliations and two folding structures, as well as shearing coeval with folding. Bedding planes within these meta-sediments are observed as intercalations of black and white chert (only Bentong-Raub) as well as quartz and mica rich layers within schist outcrops. The angle with the S1 foliation is small and cross-cutting relationships are rare. S1 foliation planes make up isoclinal recumbent folds with S2 forming parallel to the axial planes of these folds. Refolding of the isoclinal folds by an open-style folding postdating the development of S2 planes followed, probably coeval with shearing parallel to these fold axes. The geometries and intensity of these structures imply that progressive deformation took place during the formation of an accretionary wedge at the boundary of the subducting Paleo-Tethys Ocean and the Indochina Block. This deformational environment is confirmed by the increase of metamorphic grade (i.e. higher pressure greenschist facies) towards the Bentong-Raub zone. The metamorphism within the meta-sediments affected by D1 is related to burial within the accretionary wedge at depths of >10 km, assuming a standard geothermal gradient. The metamorphic minerals clearly show the different deformation structures, indicating that metamorphism must have occurred prior to deformation. The Bentong-Raub zone, consisting of a tectonic mélange, chert deposits, serpentinite and olivine-diabase represents an ophiolitic mélange, and is considered as part of the nappe stack associated with the closure of the Paleo-Tethys Ocean during Triassic times. The contacts between the Bentong-Raub Zone and the Ordovician-Silurian and Devonian outcrops in the west, as well as between the Bentong-Raub Zone and the Triassic rocks in the east, do not outcrop clearly. Backthrusts played an important role in accommodating the ongoing compression of the converging plates. A foreward breaking thrust is interpreted to overprint these backthrusts. To get the much younger Triassic rocks to be in contact with the Bentong-Raub Zone, a normal fault must be separating these lithologies as well.

55 Triassic deposits west of Bentong-Raub were deposited after most deformation structures formed in the accretionary wedge meta-sediments. However, the orientation of the west- vergent asymmetrically folded bedding planes and axial plane foliation (D2) do imply that the shortening direction had not (yet) changed. Most likely, the Triassic (meta-) sediments were deposited in a forearc basin related to the formation of the accretionary wedge and deformation occurred as a late-stage effect of the closure of the Paleo-Tethys Ocean and collision between the Sibumasu Terrane and the Indochina Block. This deformation is considered separately from D1, as the geometry of folding structures in Triassic rocks is different from those observed in the older meta-sediments.

Intrusion of the Main Range granite batholith occurred approximately simultaneously with the deposition of the Triassic rocks, yet the deformation structures in both lithologies are not similar enough to be considered part of the same phase. The localized deformation in the granites is characterized by very steep foliation planes and normal shear zones. These (tilted) shear zones which are part of deformation phase D3 are interpreted to have contributed to granite exhumation during Eocene – Oligocene times.

Strike-slip shearing on S2 foliation planes (L2 lineations) in the Devonian, Ordovician- Silurian and Bentong-Raub units as well as in the Main Range Granites (D4) is most likely related to extension in NW-SE direction. Some evidence of this shearing is also observed in Triassic outcrops. This shear is interpreted to be related to the Indian-Eurasian collision and subsequent clockwise rotation of SE Asia, resulting in NW-SE oriented strike-slip movements (here observed as dextral shears along L2 stretching lineations). These strike-slip movements are also associated with the formation of Cenozoic basins such as the Malay Basin east of Peninsular Malaysia. No large shears or offsets are seen in map view, so erosion must have played an important role in the exhumation of the Western Belt as well. Both normal faulting (expressed in Main Range Granites) and regional strike-slip shear, are interpreted to have accommodated large scale exhumation during Paleogene times.

Outlook Despite the extensive amount of structural data that was gathered throughout this research, more measurements and analyses of the data sets need to be done to get conclusive results regarding the large-scale structures, and to find more evidence for the suggested tectonic model. Questions especially remain unanswered regarding the timing and geometry of structures seen in the granites, as well as the contacts between the Bentong-Raub ophiolitic mélange and the surrounding units . It is of great importance that the width of shear zones within the Main Range granites is constrained. It is strongly recommended to take samples from granitic outcrops, for example along the E-W highway between Kuala Lumpur and Bentong, as macro-scale analysis has proven not to provide sufficient information.

56 ACKNOWLEDGEMENTS

First of all, I would like to thank Dr Ernst Willingshofer, Dr Thomas Francois and Dr Liviu Matenco from Utrecht University, for being my helpful supervisors during my MSc thesis. Special thanks to Ernst and Thomas for the enjoyable field days in Malaysia and fruitful discussions in the field. Furthermore, I am very thankful for the help of Dr Ng Tham Fatt and Dr Nur Iskandar Taib from the University of Malaya. I especially appreciate the time and effort that Dr Ng Tham Fatt invested in showing me many interesting outcrops around Kuala Lumpur. Then, of course, I owe great gratitude to my wonderful field partners Aya and Safa, students from the University of Malaya. Besides being my personal drivers during the entire 5 weeks of fieldwork, they helped search for outcrops, stretching lineations and shear senses of sufficient quality, and they showed me all the perks of Malay life (the food, the waterfalls, the hot springs…). Finally, I would like to thank Twan Daanen for our often fruitful discussions and his continuous availability therein, while ‘enjoying’ many, many cups of coffee during the summer.

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Tan B.K. (1984). Tectonic framework and evolution of the central belt and its margins, peninsular Malaysia. Bull. Geol. Sot. Malaysia 17, 307-322.

Tapponnier, P., Peltzer, G. & Armijo, R. (1986). On the mechanics of the collision between India and Asia. In: Coward, M.P. & Ries, A.C. (eds) Collision Tectonics. Geological Society, London, Special Publications, 19, 115–157.

Wakita, K. & Metcalfe, I. (2005), Ocean plate stratigraphy in East and Southeast Asia. Journal of Asian Earth Sciences, 24, 679-702

59 APPENDIX 1 GPS COORDINATES AND ORIENTATION MEASUREMENTS

Bentong-Raub zone

GPS Coordinates Stop no. X Y Outcrop description

Contact continental red beds/conglomerates with chert. Fault 1.3 101,90266 3,6080485 contact; cherts possibly show drag.

Chert; soft-sediment deformation is very apparent. Clear foliation wrapping around large blocks of different lithologies such as 1.4 101,90213 3,6048455 sandstone and pyroclastics. Slate/shale with carbon-rich layers. Strongly foliated and faulted, 1.5 101,90224 3,5929087 showing flexural slip. 5.9 102,00944 3,4428627 (Ribbon) chert. Very weathered outcrop. Alternation of differently coloured clay-rich rock (shale?). Very 5.10 102,02739 3,4571677 weathered.

Slate/shale. Strongly foliated, very fine micas occasionally present. 6.7 101,90108 3,5910018 Also more sandy/competent layers.

Slate/shale and chert. Very messy rock (mélange), folded and foliated. Some more mica-rich layers and pyroclastics present 6.8 101,90224 3,5929087 within very deformed country rock 7.1 102,03 3,4173041 Unmetamorphosed limestone. 7.2 102,03071 3,415159 Weathered (red) limestone. 7.3 102,02953 3,4121344 Weathered limestone.

7.5 101,9988 3,4457048 Very weathered (red) clay-rich/CaCO3-rich sediments. alternation of differently coloured clay-rich rock (shale?). Very 7.6 101,98486 3,4347283 weathered. Carbon-rich shale alternated with lighter coloured sediments. Very 7.7 101,99188 3,4489779 weathered. 8.4 101,97842 3,4659087 Metasediments/deformed sand/siltstone.

8.5 101,95966 3,4787254 Sandstone alternated by coarser clastics/conglomerate. 14.1 101,90213 3,6048455 Same location as 1.4. Biotite-mica schist. S1 isoclinally folded, S2 is dominant foliation 15.4 101,80904 3,8880011 plane in outcrop. 15.5 101,80249 3,896101 Serpentinite 15.6 101,81332 3,8881221 Contact micaschist and conglomerate. 15.7 101,64496 3,9880297 Undeformed microgranite. 15.8 101,78081 3,9731658 Undeformed sandstone.

15.9 101,77849 3,9717029 Very weathered foliated rock near serpentinite waste/iron ore mine. 16.4 101,90224 3,5929087 Same location as 1.5. 23.1 101,81332 3,8881221 Contact conglomerates (foliated) with schist.

60 23.2 101,80904 3,8880011 Biotite-mica schist. Same location as 15.4. Recrystallized pelloidal limestone block in conglomerate and schist. 23.7 101,77923 4,3056302 Not sure if in situ. 23.8 101,77542 4,311013 Very weathered 'schist', more like siltstone. Slate with blocks of sandstone and pyroclastics. Strongly folded and 24.8 foliated. 25.2 101,99188 3,4489779 Same location as 7.7. 25.3 101,971 3,4722777 Sandstone. 25.4 101,8419 3,7635498 Sandstone. 25.5 101,84589 3,7609426 Sandstone alternated with clay-rich layers. 26.1 101,87263 3,6242429 Slate. 27.1 101,97842 3,4659087 Same location as 8.4. 28.1 101,90108 3,5910018 Same location as 6.7. Slates, chert and pyroclastics. Mélange. Round clasts/accretions 29.15 101,71868 4,2457435 present. 29.16 101,72181 4,199851 Polymicked conglomerate surrounded by weathered schist. 30.1 101,85065 3,7633326 Very coarse sandstone, sometimes with small pebbles.

61 S0 - Bedding planes S1 foliation S2 foliation Stop Dip Dip Dip no. Strike Dip direction Strike Dip direction Strike Dip direction 1.5 160 75 SW 5.9 162 90 5.10 176 60 E 6.7 126 50 NE 146 86 SW 126 34 SW 150 84 SW 58 48 NW 146 70 S 6.8 126 66 N 154 84 S 172 68 W 7.1 148 62 NE 152 76 NE 7.4 46 50 NW 7.5 148 80 NE 134 82 NE 7.7 135 40 SW 122 80 SW 8.4 100 82 N 142 84 E 146 76 W 132 88 E 98 64 N 170 86 E 162 44 W 138 80 SW 120 62 SW 120 78 N 14.1 132 74 NE 15.4 176 54 W 168 46 W 15.5 174 64 E 132 48 NE 148 68 E 124 64 NE 15.6 114 62 NE 132 78 SW 114 38 SW 174 46 E 15.9 126 62 NE

62 16.4 162 88 W 150 70 E 174 48 W 166 38 W 176 66 W 146 52 W 176 66 W 160 56 W 168 86 W 164 76 W 176 78 W 164 42 SW 138 78 E 146 76 W 23.1 76 48 E 34 86 NW 23.8 38 30 SE 24.8 166 46 W 24.9 4 74 W 25.2 120 82 S 25.4 158 70 SW 25.5 6 82 E 12 64 E 26.1 160 74 W 160 86 W 27.1 142 84 E 132 88 E 170 86 E 146 76 W 120 78 N 28.1 142 80 E 139 82 E 146 84 E 150 54 W 128 24 NE 14 54 W 150 64 W 29.15 156 86 NE 148 65 SW 142 68 W 137 46 NE 156 68 E 146 64 E

63 30.1 24 32 E 11 44 E 166 70 E 156 68 E 146 64 E

Fold axes S0 Fold axes S1 Stop no. Trend Plunge Trend Plunge 1.4 144 10 15.4 130 18 8.4 276 50 178 46 278 38 138 24 336 46 170 38 14.1 152 16 140 28 146 34 148 18 110 42 15.6 326 36 132 50 98 12 124 58 148 20 148 32 24 40 186 70 40 20 110 34 15.8 146 30 116 44 150 28 120 34 16.4 216 40 106 28 164 4 128 34 86 42 138 30 170 54 144 20 126 34 90 42 26.1 50 46 114 20 27.1 340 46 334 60 28.1 22 72 142 42 136 20 322 22 154 12 112 6 142 20

64 Foliation Lineation Stop Dip no. Strike Dip direction Trend Plunge Shear sense 7.6 46 50 NW S1 260 30 No asymmetries observed 14.1 S1 24 66 very vague lineation 15.4 168 46 W S2 71 44 crenulation lineation? 15.5 174 64 E S2 192 38 lineation str lin, top up --> 324; check foliation planes 23.2 S2 142 18 at 15.4 --> NW 24.8 166 46 W S1 180 22 sample taken 206 26 24.9 4 74 W S1 220 72 str lin (?); then top down to 220 --> SW 25.2 120 82 S S1 66 76 top up --> 242 --> SW 25.4 158 70 SW S0/S1 193 58 probably top up --> 13--> N very vague; probably top down--> 82 (E) but 25.5 12 64 E S1 82 62 some top up also seen 27.1 142 84 E S2 338 38 possible, very vague str lin; top down? 170 86 E 346 42 Top down? ( NW) 26.1 160 74 W S1 274 70 160 86 W 254 76 104 86 S 286 22 other lineation? 28.1 142 80 E S1 324 21 Probably top (N) to E 139 82 E 318 0 130 4 sample taken (M21B) 29.15 142 68 W S1 328 8 122 52 SW 142 36 Top down?? Shear bands may show top up 137 46 NE S1 334 21 30.1 146 64 E 128 64 very very vague lineation 13.1 42 70 NW S1 246 30 str lin

65 Fault planes Fault striations Stop Dip no. Strike Dip direction Trend Plunge Shear sense 1.3 158 65 NW 100 76 top to 280 1.4 140 80 S 132 28 106 54 S

1.5 174 82 W 180 45 slickensides 170 70 W 280 68 top to 280 146 30 SW 284 50 top to 284 145 61 W 7.2 40 46 NW 16 18 top to 196 if Riedel is true 158 65 SW 38 0 38 50 SW 72 54 SW 138 24 SW 4 46 SE 8 10 W Very vague, if Riedel then top to 7.6 72 70 SW 82 24 82 60 40 S 164 42 Crenulated?? Then top to 344 60 42 S 74 34 S 7.7 184 84 E 4 86 top to 184 8.5 120 90 154 50 W 104 82 S 14.1 36 64 NW 238 42 66 84 S 15.6 164 40 NE 16.4 108 44 SW 270 21 perhaps top to 90? 164 70 W 8 90 28.1 2 34 W 354 2 Thrust?? --> otp to 174 169 36 W 314 26 thrust(?) --> top to 134 168 70 W 344 8 top up, to 164 146 84 E 178 20 on same plane, no shear sense 112 72 S 326 24 184 70 thrust? Top to 4

66 Ordovician-Silurian east of Kuala Lumpur

GPS Coordinates Stop no. X Y Outcrop description 1.6 Metasediments, isoclinally folded and sheared. Garnet mica-schist with quartz veins and graphite layers. Very 2.3 101,88682 3,5683894 weathered, two foliations observed. Contact granite and schist with some pegmatitic veins. Granite is 3.3 101,77597 3,2126049 undeformed. 6.9 101,88682 3,5683894 Same location as 2.3. Garnet Mica schist Very weathered sediment. Colouring implies that it might originally 8.6 101,93378 3,4800102 have been a schist. 8.7 101,90743 3,4740675 Quartz vein, 6m wide, intercalated by schist. 8.8 101,89897 3,4644251 Folded schist, folds are often associated with faults and show drag. 8.9 101,89852 3,4542602 Similar to 8.8, quartz veins are more apparent here. 8.10 Metasediments. 9.8 101,77059 3,3369264 Weathered metasediments, fine-grained mica. Very faulted. 9.9 101,76389 3,3310617 Schist? 14.3 102,21731 3,0061981 Schist, possibly S2 observed. 17.1 101,89846 3,47113 Strongly folded and foliated schists. 17.2 101,89501 3,4603409 Very weathered rock. Schist? 17.3 101,898 3,4548316 Very weathered folded schist. 18.1 101,94751 3,1215264 Metasedimentary schist. Harder than normal schist. 18.2 101,95655 3,117988 Metasediments. 18.3 101,9652 3,116022 Metasediments. 22.1 101,77597 3,2126049 Same location as 3.3. 26.1 101,87263 3,6242429 Slate. 27.2 101,88682 3,5683894 Same location as 2.3 and 6.9. 29.2 101,66902 4,3465364 Slate. 29.6 101,68026 4,311185 Folded sediments, weathered, might have been schist. 29.7 101,68397 4,3075592 Schist? Some slate seen as well. 29.8 101,68635 4,3003959 Cooked' schist. 29.9 101,68945 4,2953457 Unfoliated microgranodiorite. 29.10 101,68818 4,2972969 Weathered schist. 29.11 101,69025 4,2837532 Weathered schist. 29.12 101,68968 4,2820316 Metasediments, folded. 29.13 101,70762 4,2540084 Schist with some chert layers or metamorphosed schist. 29.14 101,71321 4,2527929 Intercalation of chert, slate and schist. 30.2 101,88682 3,5683894 Same location as 2.3 and 6.9 and 27.2. 30.3 101,89897 3,4644251 Same location as 8.8. 30.4 101,89852 3,4542602 Same location as 8.9. 31.1 101,89846 3,47113 Same location as 17.1.

67

S1 foliation S2 foliation Dip Dip Stop no. Strike Dip direction Strike Dip direction 2.3 2 82 E 162 60 W 60 26 N 6.9 19 88 W 8 80 E 4 76 W 30 68 W 172 62 W 168 62 W 152 62 W 2 80 E 8.7 138 90 33 76 S 8.8 68 28 S 158 48 NE 160 50 SW 178 10 E 8.9 80 28 S 90 80 N 132 42 NE 14.3 116 28 N 3.3 0 47 W 148 45 W 9.8 160 70 NE 124 82 N 146 70 NE 9.9 158 60 NE 2 28 E 164 62 E 158 64 E 166 84 W 8.10 =1.6 172 30 E 132 44 N 162 34 NE 198 42 NE 18.1 154 62 SW 154 52 SW 18.2 150 52 SW 18.3 170 28 W

68

17.1 108 32 N 130 22 NE 118 39 S 17.2 154 36 NE 134 48 NE 22.1 18 56 W 18 60 W 2 64 W 144 34 SW 0 54 W 36 70 NW 178 66 W 172 78 W 2 78 W 29.2 42 78 E 29.6 4 44 W 12 68 E 138 72 SW 164 38 W 29.7 50 24 W 168 84 W 106 50 N 120 50 N 54 38 N 34 38 W 170 50 E 96 30 N 65 34 SE 134 42 SW 29.8 154 64 SW 140 82 SW 162 52 SW 161 58 SW 29.10 24 60 W 29.11 160 46 W 166 78 W 29.12 179 36 E 2 14 W 176 26 E 140 23 SW 2 8 W 34 68 SE 42 38 E 92 54 S

69 29.13 124 54 SW 176 54 W 29.14 148 66 W 174 82 W 30.2 30 82 E 30.3 146 18 E 164 20 E 30.4 79 52 N

Fold axes S1 Fold axes S2 Stop no. Trend Plunge Trend Plunge 2.3 140 70 196 30 6.9 286 56 8.9 280 4 9.9 154 48 156 36 144 44 38 18 18.1 262 36 17.1 346 40 304 6 27.2/8.4 346 72 44 64 29.12 42 46 29.13 206 75 30.2 14 28 30.3 140 6 128 20 164 12 136 14 30.4 314 48 1.6 60 18

70 Foliation Lineation Stop Dip no. Strike Dip direction Trend Plunge Shear sense 1.6 86 25 N S1 330 38 148 42 E S1 339 20 top to 159 2.3 2 82 E S2 174 35 3.3 148 45 W S1 260 40 6.9 19 88 W S2 52 80 unsure 30 68 W S1 298 36 Top to E?? 8.8 178 10 E S2 156 4 8.10 172 30 E S1 44 28 top to 224?? Vague 162 34 NE S1 217 18 18.1 154 52 SW S1 218 50 Very vague, no top to observations 18.2 150 52 SW S1 256 46 not sure; no top to observations, sample taken 18.3 170 28 W S2 312 26 Clear!;no top to observations, sample taken 17.1 130 22 NE S1 306 2 str lineation or just fold axis lineation? S1 296 3 str lineation or just fold axis lineation? 22.1 18 60 W S1 230 48 str lin or striation 144 34 SW S1 216 28 0 54 W S1 242 60 172 78 W S1 180 62 Unclarity on shear sense: shear bands generally show Top to N (up); garnet clasts top 27.2 8 70 W S2 200 33 to S 7 70 W S1 190 22 S1 180 34 29.6 164 38 W S1 310 16 Top up --> 130 29.7 120 50 N S1 328 40 very vague str lin; top up --> 148 96 30 N S1 290 36 29.8 162 52 SW S1 278 48 161 58 SW S1 284 54 sample taken for shear sense; // fault 30.2 30 82 E S2 206 36 Probably top down (S2) --> 206 30.3 146 18 E S2 338 14 top to 158, unclear if up or down 164 20 E S1 156 8 30.4 79 52 N S1 314 48 probably crenulation, top to 134 (up) 31.1 146 26 NE S1 308 6 top up, to 128

71 Fault planes Fault striations Stop Dip Shear no. Strike Dip direction Trend Plunge sense 8.8 136 28 SW 220 10 top to 40

top to 104 92 20 SW 104 6 (NE to 104) 50 24 SE 156 4 118 40 NE 178 10 E 3.3 10 64 SW 232 64

if 158/84E is Riedel of 164/70N--> 9.8 164 70 N 356 40 top to 356 158 84 E 18.3 68 76 N 43 70 SE 17.1 154 64 E 18 64 top to 198 152 56 E 17.2 26 66 E 22.1 4 50 W 262 48 98 85 N 280 52 contact

176 52 W 212 52 on footwall possibly str 16 52 W 220 44 lin

e-block 2 44 W 326 6 (top) to 326 0 66 W 142 70 E

72 Ordovician-Silurian west of Kuala Lumpur

GPS Coordinates Stop no. X Y Outcrop desription Large scale folded (and sheared) rock. Very light colouring, very fine- grained mica observed in some places, intercalated by more 4.2 101,55426 3,5665339 competent, sandy parts. Schist/shale-type rocks, similar to Devonian outcrops but not equally 4.3 101,535 3,568497 deformed. Phyllite-schist; strongly folded and foliated rock. Some mm-cm thick competent quartz layers. Two foliations observed of which one is 21.1 101,65995 3,5340539 isoclinally folded. 32.2 101,65995 3,5340539 Same location as 21.1

S0 - Bedding plane S1 Foliation S2 foliation Stop Dip Dip Dip no. Strike Dip direction Strike Dip direction Strike Dip direction 4.2 130 42 NE 76 38 N 110 34 N 180 35 W 4.3 2 38 E 30 44 SE 21.1 8 88 NW 8 56 NW 8 70 W 8 82 W 10 50 E 4 74 E 14 88 NW 8 72 E 8 50 W 32.2 6 76 E 176 88 W 178 88 W 10 66 W 6 68 W

73 Axial planes Fold axis Stop Dip no. Strike Dip direction Trend Plunge 21.1 161,2 89 E 56 2 178,7 87 W 124 34 14 88 NW 18 2 8 72 E 207 60 8 50 W 206 24 356 60 24 20 178 18 160,8 22 352,4 65,1

74 Foliation (S2) Lineation Dip Stop no. Strike Dip direction Trend Plunge Shear Sense 32.2 176 88 W S2 176 50 top' (W) --> N (up) 178 88 W S2 192 60 top to N (up) probably top up --> N; lineation // to 6 68 W S2 188 30 isoclinal fold hinges S1

Granites east of Bentong-Raub

GPS Coordinates Stop no. X Y Outcrop description Foliated felsic rock (qtz, feldspar & amphibole) with mafic-like 5.4 101,947 3,88525 enclaves/dykes. 5.5 101,944 3,89431 Cooked' quartz-rich sediments. 5.6 101,901 3,89822 Felsic rock containing quartz-like minerals. Very fine-grained matrix. 7.4 102,214 3,49205 Skarn-like, light-coloured rocks with black mineral accretions. Undeformed, coarse granite. Some enclaves of (restitic?) mafic 14.1b 102,184 3,25388 material. Deformed(?) granite. Pink K-feldspars are undeformed but hornblende 14.5 102,32 3,17501 might be aligned. 14.6 102,257 3,21197 Quartzite in contact with undeformed granite. 16.1 102,257 3,21197 Same location as 14.6. Acid/intermediate volcanic rocks, fine-grained, interbedded by pyroclastics displaying flow patterns without sorting in grain size (--> 23.5 101,811 4,29307 relatively low energy). 25.1 102,134 3,51805 Aplite and rhyolite interbedded. Both undeformed.

Foliation Stop Dip no. Strike Dip direction 5.4 2 80 W 14.6 162 78 W 16.1 170 82 E 5.6 178 78 E 8 68 W 23.5 14 50 E

75 Fault planes Stop Dip no. Strike Dip direction 7.4 22 32 E 22 36 E 46 32 E 74 88 N 103 42 S 14.5 134 10 SW 174 30 W 146 38 SW 23.5 46 52 NW

76 Granites west of Bentong-Raub

GPS Coordinates Stop no. X Y Outcrop description Partly sheared granite with some chloritization. Quartz veins may be start of 2.1 101,70407 3,5702915 localization of shear zones. Shear zones vary from 20 cm thickness to 12 m. 2.2 101,71405 3,5679982 Metasediments, rich in biotite and maybe actinolite. 3.4 101,84397 3,3620689 Sheared granite, +/- 20 m wide. 3.5 101,7907 3,3503827 Shallow intermediate-acid intrusive rock, undeformed. 8.1 101,79588 3,3549085 Very fine-grained granite, rich in quartz, undeformed. 8.2 101,79806 3,354364 Idem. As 8.1 8.3 101,80296 3,3554528 Idem. As 8.1 and 8.2, faulted rock. 8.9 101,89852 3,4542602 Folded schist with very apparent quartz veins. Folds often associated to faults. Sheared granite. Outcrop not good: because of faulting/jointing, rocks may have been 9.1 101,88925 3,3951221 moved --> measurements unsure. 9.2 101,87901 3,3845175 Undeformed granite. Feldspars show magmatic foliation. Boulders. 9.3 101,87269 3,3819691 Unsheared granite. 9.3a 101,87298 3,3813741 Undeformed granite. Feldspars show magmatic foliation. Boulders. 9.4 101,85438 3,369552 Very weathered granite. Thin section Safa showed shearing. 9.5 101,84795 3,363928 Undeformed granite and microgranite. 9.6 101,85438 3,369552 Sheared/deformed microgranite. 9.7 101,79378 3,3521059 Perhaps slightly foliated fine-grained granite. 15.7 101,64496 3,9880297 Undeformed microgranite 17.4 101,89937 3,4500109 Unsheared granite, perhaps a boulder. 17.5 101,8693 3,3779308 Undeformed granite, biotite very euhedral. 17.6 101,87275 3,3834401 Very weathered, unsheared granite. 17.7 101,86804 3,3813741 Unsheared microgranite. 17.8 101,85438 3,369552 Unsheared fine-grained granite. 17.9 Same stop as 3.4. 17.10 102,04773 3,0749089 Sheared granite 20-30 m wide. 18.4 102,02424 3,0960234 Sheared granite. 19.1 101,97954 2,8291379 Unsheared granite with pegmatitic veins. 19.2 101,96757 2,8484613 Undeformed granite with large clusters of biotite. 19.3 101,83441 2,8298042 Undeformed granite. 21.2 101,70407 3,5702915 Same location as 2.1. 29.1 101,64042 4,3916448 Undeformed, faulted granite. 31.2 101,83567 3,3777012 (Ultra)mylonite? Tiny grain size, heavily weathered. 20 cm wide. 32.3 101,77847 3,3660845 Undeformed granite. 32.4 101,75989 3,4188366 Deformed granite, unsheared. Probably not in situ.

77 Foliation Stop Dip no. Strike Dip direction 9.1 104 44 S 106 28 S 118 52 SW 126 52 SW 9.6 158 72 E 120 78 N 9.7 132 74 N 3.4 146 88 NE 156 82 E 138 80 NE 2.1 132 82 SW 145 56 SW 2.2 168 53 W 17.10 132 82 SW 18.4 146 85 W 154 86 W 150 86 W 21.2 106 74 N 120 85 SW 31.2 156 44 NE 146 38 E 32.4 64 78 N

78 Foliation Lineation Stop Dip no. Strike Dip direction Trend Plunge Shear sense 9.1 260 4 228 26 very vague str lin 118 52 SW 226 46 126 52 SW 226 45 9.6 158 72 E 54 48 str lin 3.4 146 88 NE 344 88 str lin (unsure!!!) (top to 164 if 344/86 is correct which is strongly 156 82 E 35 86 doubted) WEST-block UP (normal) 2.1 132 82 SW 208 78 top to 208 145 56 SW 228 44 str lin or fault striation; top to 228 2.2 168 53 W 208 30 21.2 106 74 N 94 68 possible str lin in microgranites

grains too small & weathered for shear sense. 31.2 146 38 E 128 10 MAYBE top down 17.10 132 82 SW 308 16 top to 134 or 128  sinistral 314 32 vague top to observations, looks like W-block up - 18.4 154 86 W 338 38 -> 154-158, so thrust 150 86 W 334 36 str lin, vague 9.1 106 28 S 114 4 very vague; shear bands: top to 114 (dextral)

Fault orientations Fault striations Stop Dip no. Strike Dip direction Trend Plunge Shear sense 9.3 10 84 W 0 60 vague 184 84 W 9.5 156 56 W 275 12 steps: top to 95 54 84 S 268 6 If Riedel: top to 268??? 104 76 N 94 59 S 90 74 S 9.6 90 88 N 152 88 E 144 6 9.7 100 84 N 284 36 top to 104 3.4 78 74 S 54 72 S

8.1 118 14 W 92 54 very vague 4 74 W 102 70 W

79 8.2 72 78 S 100 60 100 80 N 8.3 72 80 S 138 84 SW 296 22 top to 116 122 68 SW 324 34 top to 144 54 58 SW 310 64 top to 130 154 74 SW 24 68 E 68 54 NW 60 38 NW 176 60 W 8 68 W 15.7 50 62 NE 16 72 W 68 86 S 80 90 48 72 NW 17.6 102 76 S 118 64 S 17.7 136 42 N 106 84 S 17.8 102 57 N 17.10 86 56 S 80 14 18.4 32 85 E 29.1 104 71 N 55 64 thrust(?) 176 47 E 316 45 thrust(?) 0 75 E 84 64 S 77 86 N 77 84 S 82 78 N 163 62 E 2 60 W

80 Triassic

GPS Coordinates Stop no. X Y Rock Type Permo-Triassic sediments, slightly metamorphosed, up to shale. S0 folded, S1 axial 1.1 101,87932 3,7589829 plane foliation. West-ward vergence of S0 folds. 5.1 101,96033 3,6253906 Very weathered, foliated Permo-Triassic sediments. 5.2 101,97874 3,6255525 Idem. To 5.1 Felsic volcanic rock with quartz-like porphyroblasts, overlying un-metamorphosed, 5.6 101,90098 3,8982163 strongly weathered sediments 5.7 101,84901 3,9436266 Very weathered non-metamorphosed sediments. Very weathered clay-rich sedimentary rock, folded foliation and bedding 6.1 101,88996 3,8144661 (unmeasurable) observed. Folded foliation in very weathered clay-rich sediments. Some asymmetry in folding 6.2 101,89018 3,8132342 observed. Slightly metamorphosed rock (fine sandstone), up to shale. S0 is generally subparallel 6.3 101,90577 3,7517515 to its axial plane foliation, S1. West-ward vergence of S0 folds. 6.4 101,90389 3,7523796 Idem. To 6.3. 6.5 101,89279 3,7551013 Idem. To 6.3; double (i.e. in two directions) asymmetric folding of bedding. 6.6 101,88337 3,7574043 Idem. To 6.3. 14.4 102,37154 3,1480027 Chert, interbedding of light and dark layers. 15.1 101,86406 3,8033403 Coarse sandstone, weathered. Clay-rich, slightly metamorphosed (<< phyllite) rock interbedded with sandstone. 15.2 101,86935 3,8075801 Foliation is parallel to this interbedding. 16.1 102,25719 3,2119736 Quartzite in contact with granite. 16.2 102,23911 3,1963379 Very weathered clay-rich, strongly foliated sediments. 23.6 101,79359 4,302939 Conglomerate with offset fractured pebbles. 24.1 101,90577 3,7517515 Same outcrop as 6.3. 24.2 101,90389 3,7523796 Same outcrop as 6.4. 24.3 101,89279 3,7551013 Same outcrop as 6.5; 2 deformation structures confirmed. 24.4 101,88337 3,7574043 Same outccrop as 6.6. 24.5 101,87932 3,7589829 Same outcrop as 1.1. 24.6 101,88996 3,8144661 Same outcrop as 6.1. 24.7 Same outcrop as 5.6. 28.2 102,03071 3,415159 Weathered limestone. Weathered white rock, originally dark grey. Interpreted to have been metamorphosed at 28.3 101,8693 3,7884854 a lower grade than phyllite. 28.4 101,87258 3,7691131 Idem. To 28.3. 28.5 101,87049 3,7680673 Idem. To 28.3, but large scale folding shown. 29.17 101,79306 4,2203995 Permian sediments; non-metamorphosed.

81

S0 - Bedding planes S1 Foliation S2 foliation Stop Dip Dip Dip no. Strike Dip direction Strike Dip direction Strike Dip direction 1.1 170 54 E 162 50 NE 50 36 S 5.1 154 50 N 166 70 NE 70 22 NW 160 61 NE 168 76 E 162 62 NE 156 54 NE 173 62 E 1 70 E 5.2 154 64 SW 5.6 178 78 E 8 68 W 5.7 188 78 E

6.1 62 68 NW 158 82 E 32 70 NW 166 88 E 0 78 W 162 86 E 170 58 W 6.2 163 74 E 4 64 E 162 82 E 52 34 S 126 30 S 152 74 E 124 62 NE 6.3 4 78 E 160 88 E 6.4 167 58 E 159 70 E 6.5 150 20 E 135 82 SW 150 34 SW 178 20 E 46 70 NW 6.6 176 50 E 170 68 E 4 56 E 14.4 154 47 N 168 81 E 174 52 W 90 85 S 166 70 W

82 15.1 172 18 W 15.2 172 66 E 170 68 E 4 56 E 16.1 152 74 W 156 86 W 170 82 E 16.2 138 20 SW 150 70 E 23.6 2 76 E 24.1 1 78 E 24.2 166 64 S 24.3 116 84 SW 160 66 E 24.4 14 47 E 24.5 160 64 E 28.2 170 60 E 28.3 174 64 E 176 57 E 28.4 172 64 E 0 62 E 28.5 152 66 SW 102 44 SE 136 64 NE 16 14 E 8 54 E 29.17 26 60 E 14 84 W

Fold axes Stop no. Trend Plunge 6.2 170 40 S0 6.5 150 24 S0 24.3=6.5 86 20 S0 142 14 S0 290 46 S1 340 2 S1 20 40 ?

83 Foliation Lineation Dip Stop Strik Di directio Tren Plung no. e p n d e Shear sense 1.1 162 50 NE 163 5 intersection S0-S1 5.1 166 70 NE 358 16 6.5 152 22 intersection foliation and bedding 24.1 1 78 E 164 86 162 86 top up --> 344 24.2 166 64 S 86 66 top down 24.4 14 47 E 40 40 top down, but not convincing 24.5 160 64 E 354 2 6 0 top down --> N (probably) 24.6 330 30 28.2 170 60 E 164 8 28.3 174 64 E 2 60 E; top (E ) down, to N--> 16 if based on E-dipping dominant foliation --> top down --> 29.17 14 84 W 176 72 176

Faults Striations Dip Stop no. Strike Dip direction Trend Plunge Shear sense 5.1 82 70 S 14.4 90 85 S 254 78 16.1=14.6 140 82 E 98 86 NE 84 86 S Top to 152 156 86 W 332 58 (?) 320 16 24.7 14 82 W 16 52 W

84 Devonian

GPS Coordinates Stop no. X Y Outcrop description Strongly foliated and folded schists in which mica-rich layers are interbedded with mm-cm thick quartz-rich and more competent layers. Isoclinal recumbent folding also commonly observed. Faults cut off 4.1 101,57337 3,4187547 some fold structures. 4.5 101,447 3,323434 Strongly weathered folded schists. Sandstone alternated with shale. Pinching out of layers observed; no indication of whether this is deformational or non-deformational structure. Small-scale folding only seen in association with small- 10.7 101,54762 3,3513572 scale faults. 11.1 101,57337 3,4187547 Same location as 4.1. Very similar rocks to those at locations 4.1 and 11.1; outcrop less well 12.2 101,56921 3,4226729 exposed. Small outcrop in which two foliations are clearly visible. Quartz veins 12.3 101,56487 3,4223115 are very apparent and isoclinally folded. 13.1 101,56487 3,4223115 Same location as 12.3. 19.4 101,8033 2,842674 Very weathered schist-like meta-sediments. Very weathered, strongly foliated white meta-sediments; lower grade 19.5 101,8033 2,8394397 than phyllite. Shale-like folded and foliated rock underlying the white meta- 19.6 101,80499 2,8400557 sediments of 19.5. Very similar rocks to those at locations 4.1 and 11.1; outcrop less well 20.0 101,56921 3,4226729 exposed. Idem. As 12.2. 32.1 101,57337 3,4187547 Same location as 4.1 and 11.1.

85

Stop number S1 S2 Dip Dip Strike Dip direction Strike Dip direction 11.1 124 4 S 46 66 S 46 46 SE 168 44 E 172 38 E 166 54 E 150 53 NE 82 42 SE 58 34 S 88 30 S 94 8 S 132 20 SW 84 28 S 108 48 S 110 30 S 162 44 SW 114 12 E 140 80 S 39 22 W 120 68 S 86 24 S 124 38 S 66 2 SE 74 24 S 64 28 SE 150 40 SW 38 32 E 126 34 S 58 30 S 156 42 SW 10.7 140 20 N 128 26 N 162 44 N 126 30 N 12.3 20 26 E 13.1 30 10 E 164 12 E 174 14 E 4 22 E 126 14 SW 19.4 66 52 N 82 5 N 19.5 42 32 NW 52 40 NW 28 38 NW 32 30 NW 19.6 26 42 NW 122 38 NE 40 54 NW 2 10 W 22 40 NW 108 28 S 48 46 N 94 20 S

86 20.1 22 28 NW 22 74 E 150 18 NW 16 62 E 90 58 S 32 80 E 158 24 W 126 54 S 1 66 W 162 48 W 178 14 W 138 58 W 142 52 NE 34 58 W 37 12 NW 126 56 W 28 58 NW 6 29 W 20 26 NW 178 74 W 28 76 NW 38 48 NW 20 74 NW 176 62 W 24 35 NW 96 66 S 174 58 W 166 60 W 20 72 W 160 50 SE 32.1 166 42 SW 118 54 S

87 Phase 1 folds (F1) - tight to Phase 2 folds (F2) - open Stop isoclinal, recumbent folding of folding of axial plane foliation Phase 3 folds (F3) - asymmetric number S1 S2 folding making up S3 Trend Plunge Trend Plunge Trend Plunge 11 208 24 76 42 326 40 222 44 84 34 156 50 126 68 190 54 136 40 154 42 182 52 162 50 54 46 316 58 160 34 178 44 180 44 88 60 160 50 150 42 162 68 144 40 98 44 104 46 124 34 235 24 124 52 84 44 122 44 104 60 18 50 170 20 158 20 274 20 188 40 270 8 170 4 176 64 105,3 12,5 140 44 149,7 55,9 183,3 39,5 217,1 15,6 314,6 9,2 142,2 10,4 59,2 29,5 130,9 49,3

88 4.1 111 58 75 40 129 46 96 32 78 8 90 34 134 34 76 50 142 46 174 5 166 3 146 34 66 28 165 8 4.5 176 90 4.5 152,7 28,5 12.2 195,8 20,9 12.3 238 20 336 20 344 14 31 6 4 4 38 6 13.1 24 12 6 2 174 8 10 4 62 18 356 14 4 6 264 30 353 16,8 349,1 6,1 19.6 28 8 270 16 312 12 252 52 222 10 20.1 90 62 240 28 316 54 246 54 346 66 238 68 25 42 52 52 206 42 2 34

89 32.1 90 12 100 12 108 34 112 42 156 18 105,9 35,1 90,6 14,4

Stop no. Axial planes of S1 folds Axial planes of S2 folds Dip Dip Strike Dip direction Strike Dip direction 11.1 156 82 SW 136 40 NE 138 60 S 156 42 E 12 64 E 167,6 71,8 W 154 40 E 158 48 NE 66 68 SE 132 60 N 114 40 S 116 4 S 106 18 N 164 40 W 126 66 N 90 22 N 66 38 SE 108 14 S 112 8 S 50 10 SE 66 36 S 130 28 S 98,5 61,7 S 90 70 S 118,5 70,6 S 81,5 21,8 S 140,8 82,4 W 115,1 76,8 S 134,2 87,5 S 4.1 78 32 SE 133,3 82 N 178 35 W 63,3 82,8 N 176 54 E 4.5 152,8 89,7 E 12.2 17,7 85,3 E

90 12.3 64 36 NW 20 18 NW 160 44 E 160 10 NE 4 86 W 18 40 W 13.1 10 72 E 14 24 W 176 68 E 46 14 W 13.1 182,8 60,4 W 337,9 28,6 E 32.1 100,8 82,7 S 86,8 75,6 S

Stop number Foliation Lineation Dip Strike Dip direction Azimuth Plunge Comments 11.1 136 58 SW S2? 254 54 Lineation on this plane 110 16 S S1? 270 22 Intersection lineation?? On qtz vein; probably intersection or crenulation; if str lin: top down --> 32.1 69 34 SE S1 156 32 156 166 42 SW S2 258 42 Top down?? 118 54 S S2 278 30 Probably top down Probably intersection/ crenulation 150 20 W S1 260 18 top down?? --> sample taken 172 16 W S2? 272 12 Probably intersection, top down

Stop no. Fault orientations Fault striations Dip Strike Dip direction Trend Plunge Shear sense 11.0 62 62 S 80 80 N 74 4 S to 254, strike slip

approximate fault plane; if strike slip, top to 14 74 E S 4.5 158 70 W 176 28 top to SE (if i.e. Riedel) 94 76 S 130 84 169 64 W 172 64 W 176 2 160 68 W 2 20 19.4 16 76 E 19.6 124 80 NE 20.1 70 88 NW

91 APPENDIX 2 THIN SECTION DESCRIPTIONS AND SCANS

92 Sample no. Stop no. Rock type Oriented Orientation Lineation M1 1.6 Contact metamorphic OS sediments O 148/42E 339/20 M2 2.1 Granite, mylonite O 132/82 SW 132/82 M3 3.3 Contact metamorphic OS sediments O 148/45 SW 260/40 M9 8.8 OS Schist O 178/10E 156/4 M11 18.2 Contact metamorphic OS sediments O 150/52 SW or 160/44 SW 256/46 M12 18.2 Contact metamorphic OS sediments O 150/52 SW or 160/44 SW 256/46 M13 18.4 Sheared granite O 150/86 W 334/36 M15 23.10 Microgranodiorite O 178/90 352/50 M16 24.8 Sandstone/quartzite/arcose O 166/46W 206/26 M20 26.1 Slate O 160/86W 254/76 or 274/70 M21 - A 28.1 Tectonic mélange/slate O 134/79 E 322/16 M21 - B 28.1 Tectonic mélange/slate O 139/82E 130/4 M22 (A&B) 28.2 O 170/62E 164/8 M23 18.3 Contact metamorphic OS sediments O 170/28 W 312/26 M24 29.5 Dolerite NO M25 29.8 Contact metamorphic schist O 161/58SW 284/54 M26 32.1 Devonian schist O 150/20W 260/18 M28 9.5 Undeformed granite NO

93 Sample no. Field observations Thin Section analysis Photographs M1 Contact metamorphic, isoclinal recumbent folds Layered broken down minerals. Rock folded. (largely symmetric). Mostly amphibole, quartz (clasts, as well as in matrix). No clear asymmetry observed in clasts.

M2 S-type granite (220Ma; 83-87 Ma; biotite might Deformation occurred after quartz be younger): large feldspars, hornblende, and recrystallization. Large Kfs, some severely biotite. In some places granite is undeformed, and broken up. Also some albite & maybe some in other places very sheared. Chloritization seen old, weathered minerals with Carlsbad in sheared granite and shear zones often twinning. Minor biotite. Perhaps chlorite or associated with quartz veins. Fault localization on amphibole with birefringence masked by shear zone planes. colour. Amphiboles are stretched/foliated but i.e. crosscut by folded/sheared rex qtz. White mica is also observed.

M3 Contact granite and foliated schist. Some Equidimensional quartz crystals, amphibole, pegmatitic veins (muscovite, feldspar, qtz) in muscovite, chlorite, minor feldspar. schist. No other signs of contact metamorphism. Amphibole and muscovite are irregularly Schist folds around pegmatite. Granite contains shaped, but no shearing observed (overprinted needles of tourmaline or hornblende, non- by rex qtz). Folded muscovite (tight/iso) in deformed. Qtz veins/lenses stretched (symmetric). vein/shear zone surrounded by large, non- recrystallized quartz and along chlorite.

94 M9 Qtz-rich schist. Quartz veins show pinch and Differentiated crenulation cleavage mica and swell. Foliation is folded too. Most folds quartz layers (S2). S1 isoclinally folded, i.e. associated with drag by faults. Refolding of folds mainly seen in mica layers. S2 sometimes is observed. crosscut by later deformation feature (normal movement). Tourmaline. Chlorite bands display both foliations as well. Also ‘weathered’ clast, sheared & including foliation(s): garnet???

M11 Cooked metasediments. Layering of white & Almost entirely amphibole  amphibolite? black/dark lithologies. Idem as M12, but with slightly more quartz veins. Mineral composition: chlorite, feldspar, amphibole

M12 Idem. To M11 Almost entirely amphibole  amphibolite? Mainly fine-grained amphibole. Perhaps veins/elongate aggregates of chlorite? Some quartz. Feldspar (Carlsbad twin) in vein with larger amph. Fabric seen with gypsum plate but minerals themselves seem to have no preferred orientation.

95 M13 Sheared granite, fine-grained. No large feldspars Sheared granite. observed. Folding observed. Mostly white mica in strain shadows along foliation planes. Symplectite- like structures seen. Chlorite, quartz, feldspars, amphibole. Zircon also present.

M15 Interpreted micro-granodiorite (TS shows Pyroxene, olivine, chlorite, feldspar, otherwise) hornblende, epidote? M16 Sandstone/quartzite, arcose (sandstone rich in feldspar and quartz).

M20 Slate (or chert?). Foliation planes later reactivated Very fine-grained, qtz veins along which by brittle movements. movement of foliation/shear zones are observed. Unclear mineral assemblage.

96 M21A/B Tectonic mélange/slate/chert with pyroclastic Tiny grain size. inclusions. Unknown minerals: needle-like elongated, high birefringence M22 Sandstone?

M23 Contact metamorphic (?)/cooked rocks with Two clear foliations, S1 and S2. Quartz veins clearly 2 sets of orientations in rock. One is (recrystallized) are isoclinally folded and interpreted as joints. crosscut both S1 and S2. S2 is seen to fold around the quartz veins. One part of the thin section shows clear foliation and folding. In the other part, observation of the foliation is limited by the microscopic view. When looking at the thin section without using the microscope, a clear foliation is observed, at an angle to both S1 and S2.

97 M25 Cooked schist? Not anywhere near granite Very fine-grained and weathered. Only quartz intrusion? In between ‘normal’ schists. can clearly be observed.

M26 Strongly foliated and folded schists (2-3 Clear S1 and S2 Mostly quartz (sometimes big foliations). & vein-like) and white mica. S2 is irregular. Large qtz grains stop at S2 foliations.

M27 Strongly foliated (2 foliations) schist. Mostly quartz and white mica. Some minor blue and brown tourmaline, and monazite and zircon. Quartz not equidimensional but elongated. Micas have very low birefringence. Tourmaline is not sheared but surrounding mica and quartz sometimes are. Probably tourmaline is later grown than micas & qtz & grew in 2 phases (blue and brown tourmaline).

98 M5 Either something volcanic, with infillings of vesicular holes, corroded quartz crystals, fenocrysts, calcite, OR, metamorphosed sediment, OR metamorphosed volcanic ash. Black dots are some kind of ore accreted at grain boundaries. M24 Dolerite/olivine-diabase containing olivine, serpentine, cpx, plagioclase & segregations of something possibly titanium rich M28 One very strongly folded amphibole which might show 2 foliations. Also some minor amphiboles or chlorite. Some recrystallized quartz at grain boundaries. Almost all minerals have undulatory extinction, implying folding (?). Many inclusions in feldspars: feldspar or quartz, some high birefringent minerals with cleavage. Zircon also present. Some feldspars (?) are severely weathered. Some biotite. Thin sections are thick. Sometimes wrapping structures observed.  Granite seemed to be undeformed, but thin section shows folding; or at least crystal plastic deformation.

99

100

101 APPENDIX 3 SEM-RESULTS

In the following section the chemical analyses resulting from the table-top SEM measurements on samples M9, M15 and M24 are shown. The numbers on the figures correspond to the area in which measurements were taken. Backscatter images without numbering show an overview of a larger area within the studied thin section.

102 Sample M9

Mol% Compound View 701 View 702 View 703 View 704 K2O 6,63 Al2O3 26,87 1,66 SiO2 59,96 21,55 100 CaO 69,6 FeO 6,53 1,12 BaO 6,07 Cl 100 Total 100 100 Composition

103 Sample M15

Mol% Compound View 101 View 102 View 106 Na2O 11 Al2O3 13,95 19,2 20,37 SiO2 73,38 44,28 45,29 CaO 1,66 28,71 28,41 FeO 7,81 5,93 Total 100 100 100 Composition Albite Epidote Epidote

Mol% View Compound 201 View 202 View 203 View 204 Na2O 11,45 Al2O3 14,01 19,87 18,86 SiO2 74,54 44,57 43,96 CaO 29,72 29,6 FeO 5,84 25,15 7,58 SO3 39,52 CuO 24,33 MoO3 11 Total 100 100 100 100 Copper ferrous Composition Albite Ca3(Al,Fe)3Si4 sulfide epidote??

Mol% View View View View View View Compound 301 View 302 303 304 305 306 307 Na2O 11,41 Al2O3 13,78 1,58 14,02 SiO2 74,81 47,47 41,18 CaO 75,94 92,04 20,48 29,79 TiO2 46,55 0,88 8,73 MnO 3,44 MgO 22,97 FeO 44,4 25,22 6,62 6,28 BaO 5,61 SO3 40,23 CuO 23,76 MoO3 10,79 P2O5 24,06 7,96 Total 100 100 100 100 100 100 100 Composition Ilmenite Copper ferrous sulfide Albite apatite? ? diopside? epidote?

104 Mol% View Compound View 401 402 Al2O3 14,1 0,51 SiO2 31,65 97,03 MgO 30,8 0,3 FeO 23,45 2,17 Total 100 100 Clino- Composition chlorite? Quartz

Mol% Compound View 501 View 502 View 503 View 504 View 505 Na2O 1,48 1,07 9,54 1,52 3,22 K2O Al2O3 3,6 3,36 14,5 10,05 15,6 SiO2 13,72 49,08 71,12 76,93 51,09 CaO 1,69 17,97 20,13 TiO2 34,55 0,83 MnO 2,52 MgO 4,47 20,54 2,71 6,19 3,17 FeO 33,64 7,16 2,13 5,32 6,79 BaO 4,33 Total 100 100 100 100 100 Composition Epidote?

Mol% Compound View 701 View 702 K2O 11,57 12,19 Al2O3 13,91 13,34 SiO2 73,56 74,47 BaO 0,96 Total 100 100 K- K- Composition feldspar feldspar

Mol% Compound View 801 View 802 Na2O 11,76 Al2O3 2,9 13,42 SiO2 36,79 74,82 CaO 31,27 TiO2 25,55 BaO 3,49 Total 100 100 Composition Titanite Albite

105

106 Sample M24

Mol% Compound View 001 View 002 View 003 View 004 View 005 Na2O 2,12 1,14 10,63 3,99 Al2O3 3,23 13,43 1,95 12,83 5,72 SiO2 17,25 48,41 95,04 74,31 30,52 CaO 1,45 24,63 TiO2 35,56 MnO 2,24 FeO 33,8 13,54 1,87 2,24 59,77 BaO 4,35 Total 100 100 100 100 100 Composition (Na,Al,Ca,Mn,Ba)1Fe3Ti3Si2 Fe1Ca2Si5Al1 Quartz? Albite Fe6Na1Al1Si3

Mol% Compound View 101 View 102 View 103 View 104 Na2O 11,6 Al2O3 15,44 13,16 SiO2 100 44,01 75,24 CaO 27,11 TiO2 46,46 MnO 2,75 FeO 13,44 45,68 BaO 5,11 Total 100 100 100 100 Composition Quartz FeCa3Al1,5Si4,5 Albite

Mol% Compound View 201 View 202 View 203 View 204 Na2O 11,59 K2O 1,6 Al2O3 1,67 4,63 13,53 SiO2 48,08 54,69 74,89 CaO 19,78 MgO 19,58 7,89 FeO 10,88 31,19 7,01 SO3 38,42 ZnO 45,28 MoO3 9,29 Total 100 100 100 100 Composition Fe3(K,Mg,Al)1Si5 Albite Sphalerite

107 Mol% Compound View 302 View 303 View 304 Na2O 11,18 Al2O3 1,76 13,35 1,64 SiO2 47,2 75,47 47,91 CaO 20,6 20,14 TiO2 1 MgO 19,02 20,08 FeO 10,43 10,24 Total 100 100 100 Composition Pyroxene? Albite Pyroxene?

Mol% Compound View 401 View 402 View 403 View 404 Na2O 10,44 K2O 12,3 Al2O3 14,1 13,16 11,97 11,14 SiO2 72,75 74,55 36,12 33,54 CaO 2,71 MgO 16,27 17,82 FeO 35,64 37,5 Total 100 100 100 100 Composition Albite K-feldspar? Olivine? Olivine?

Mol% Compound View 501 View 502 View 503 Na2O 11,83 Al2O3 1,36 13,75 1,36 SiO2 48,77 74,42 49,37 CaO 19,16 20,36 MgO 20,4 19,85 FeO 10,3 9,06 Total 100 100 100 Composition Pyroxene? Albite Pyroxene?

Mol% Compound View 601 View 602 View 603 Na2O 11,57 Al2O3 13,36 12,95 SiO2 75,06 33,67 MgO 19,49 FeO 33,89 50,52 SO3 40,32 MoO3 9,17 Total 100 100 100 Composition Albite Pyroxene? Ferrous sulfide?

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109