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Fieldwork Guide: Langkawi 1st Year Fieldwork 7-11 Sept 2015



1.0 AIMS The main aims of this fieldwork are as follows: 1. Identification of igneous, sedimentary and metamorphic rocks based on visual examination of hand specimens and at outcrops in the field. 2. Ability to distinguish between the main types of rocks based on their mineralogy, texture, physical and chemical properties and their mode of occurrence and formation. 3. Ability to recognize simple geological structures and understand the geological processes in their formation. 4. Understanding of the geological background and geological processes in the formation of landforms and geological landscapes that are observable on the surface of the earth. 5. Preliminary understanding of the major disciplines of geology such as petroleum geology, engineering geology, economic geology, environment geology and heritage geology. 2.0 SAFETY AND FIELD REQUIREMENTS Geological fieldwork is generally safe when a certain number of precautions are taken during this activity. Among them are: 1. Always exercising caution and think before doing something. In particular, when crossing roads make sure there are no vehicles approaching. 2. Dress appropriately for geological fieldwork. You should be able to move freely and have adequate protection from the weather. Proper shoes which provide good grip and protection for the feet should be used. No slippers are allowed. A raincoat should be part of the field work kit. 3. When approaching a rock outcrop, especially a quarry face, a road cut or a similar exposure, look above to ascertain that there are no loose blocks at higher levels. When hammering rocks at an outcrop protect your eyes and face and also make sure that no one else is endangered from pieces of rocks resulting from the hammering. Under no circumstances should anyone hammer rock at a higher level of a road cut or quarry face when people are present at lower levels. 4. Follow all instructions and report any accidents or injury urgently to the field work coordinator. 5. Observe cleanliness; all rubbish, in particular stereofoam and plastic packings should be disposed off in proper rubbish bins. If no rubbish bins are located at a site, the rubbish should be taken along until a rubbish bin is found.



3.0 GENERAL GEOLOGY OF LANGKAWI ISLANDS The Langkawi islands consist of a group of 104 islands in the Andaman Sea, approximately 30 km off the coast of northwestern Peninsular Malaysia. These islands form a part of the state of Kedah. The main and largest island is also referred to as Langkawi, with the town of Kuah which can be considered as a gateway to the islands. Only a few of the other island are inhabited. Fig. 1 show the location of Langkawi Islands.



Fig. 1: Location of Langkawi Islands, Peninsular Malaysia. The Langkawi Islands represent one of the more interesting locations for geological studies since all the three major rock types, igneous, sedimentary and metamorphic are found on these islands. In addition, this is probably one of the few places in Malaysia where an almost complete sequence of sedimentary rocks of Paleozoic age are exposed, ranging in age from Cambrian to Permian. There are four sedimentary rock formations, namely Machinchang, Setul, Singa and Chuping Formations from oldest to youngest in age. These sedimentary formations were intruded by the Gunung Raya granite, resulting in various types of contact metamorphism. A major fault, the Kisap Thrust Fault which an approximate north-south direction in the eastern part of Langkawi and a westward transport direction has resulted in the older Setul and possibly Machinchang Formation from the east to overlay the younger Chuping and Singa Formation along the central axis of Langkawi. Ongoing weathering, erosion, transport and deposition has lead to the deposition of unconsolidated sediments in the valleys and coastal plains. The geological map of Langkawi in shown in Fig. 2 and the stratigraphy in Fig. 3.



Fig. 2: General Geology of Langkawi. (Kisap Thrust Fault shown as dashed lines)



Fig. 3: Stratigraphy of Langkawi



4.0 ITINERARY PROGRAMME Day 1, 07 September 2015 (Monday)



Day 4, 10 September 2015 (Thursday)



0700 0730 1430 1500 1600 1630



0800 0830 1030 1300 1430 1700



Assemble at UTP Bus Terminal Depart from UTP to Kuala Perlis Jetty Arrive in Kuala Perlis Ferry to Langkawi Arrive in Langkawi Check-in hotel and rest



Assemble and depart from hotel STOP 7 STOP 8 Lunch STOP 9 Back to hotel and rest



Day 2, 08 September 2015 (Tuesday) 0800 0830 1030 1230 1430 1700



Day 5, 11 September 2015 (Friday)



Assemble and depart from hotel STOP 1 STOP 2 Lunch STOP 3 Back to hotel and rest



0730 0800 0900 1000 1100 1630



Assemble Depart from hotel to Jetty Ferry to Kuala Perlis Arrive Kuala Perlis Bus to UTP Arrive UTP



Day 3, 09 September 2015 (Wednesesday) 0800 0830 1030 1230



Assemble and depart from hotel STOP 4 STOP 5 Lunch 1430 STOP 6 1700 Back to hotel and rest



Group



STOP



1



2



3



4



5



6



7



8



9



A



I



II



III



IV



V



VI



VII



VIII



IX



B



IV



V



VI



VII



VIII



IX



I



II



III



C



VII



VIII



IX



I



II



III



IV



V



VI



I: Penarak VI: Teluk Yu



II: Kisap



III: Durian Perangin



IV: Kilim Jetty



VII: Bukit Malut VIII:Telaga Tujuh



V: Pasir Hitam Beach



IX: Pasir Tengkorak



5.0 LOCALITY MAP



I. Penarak V5



IX



II. Kisap



II



III. Durian Perangin



VI IV III



IV. Kilim Jetty V. Pasir Hitam Beach VI. Teluk Yu VII. Bukit Malut



VIII



VIII. Telaga Tujuh Waterfall IX. Pasir Tengkorak I VII



6.0 DETAILED FIELDWORK ITINERARY Date:



07 – 11 September 2015



Venue:



Langkawi



Participant:



90 students, 7 lecturers, 3 technologists and 2 GAs



Stop Locality



GPS location



Lithology



I



Penarak



06⁰ 18’17.3”N 99⁰ 51’32.4”E



Granite



II



Kisap



06⁰ 23’43.7”N 99⁰ 51’21.1”E



III IV V IV



VII VIII IX



Description and major geological features - Minerals: quartz, feldspar, mica - Fractures



Setul Formation - Highly deformed or fractured limestone - Slickensides are common Durian Perangin 06⁰ 24’08.5”N Singa Formation - Banded hornfels 99⁰ 49’11.9”E - Metamorphism Kilim Jetty 06° 24' 19.0" N 99° Setul Formation - Well-bedded limestone 51' 27.9" E - Gentle dipping beds Pantai Pasir 06° 25' 27.4" N 99° Quaternary - Black-coloured sands Hitam (Black 47' 28.6" E sediments - Recent sedimentation features Sand Beach) Teluk Yu 06⁰ 25’20.2”N Granite and - Porphyritic granite: feldspar (Opposite 99⁰ 46’50.2”E Quaternary (phenocryst), quartz, dark Malaysia sediments minerals kraftangan - Differential weathering museum) - Xenoliths: dark-coloured and fine-grained rocks in granite Bukit Malut 06⁰ 17’43.8”N Singa Formation - Metamorphosed argillaceous 99⁰ 47’16.4”E rocks/ hornfels Telaga Tujuh 06⁰ 22’57.9”N Granite - Granite/pegmatite Waterfall (the 99⁰ 40’23.2”E - At least 3 fracture sets st 1 waterfall) Pasir Tengkorak 06⁰ 25’50.5”N Machinchang - Sandstone and mudstone Beach 99⁰ 43’37.2”E Formation - Cross bedding - Tafoni structures



7.0 OUTCROPS’ DESRIPTIONS



7.1



STOP I PENARAK



Location: N 06⁰ 18’17.3” E 99⁰ 51’32.4”



The Kuah granite is well exposed along the coast near the Sanatorium. The granite composed of quartz, feldspar and mica (biotite and muscovite) with subordinate tourmaline. Two samples of the granite from Langkawi were dated by both the K:Ar and Rb:Sr methods. The analysis gave the ages of 217+/-8 Ma and 209+/-6 Ma respectively, indicating late Triassic age (Jones, 1978). The granite outcrops at Kuah which is probably parts of a single large stock also occur at Pulau Dayang Bunting, Pulau Tuba and Pulau Bumbon Besar.



7.2



STOP II KISAP



Location: N 06⁰ 23’43.7” E 99⁰ 51’21.1”



Well-polished Fault plane



The outcrop is a limestone quarry that is now abandoned. Slickensides and intense fracturing occurs within this rock unit suggesting the presence of faults. It is clear that the rocks have suffered some fault movements (Tan, 1981). The fault is known as Kisap Thrust. Since its postulation by Koopmans (1965), Kisap Thrust has been frequently cited in papers on Malaysian geology. Its implications on the geology and tectonic history of the Northwest Peninsular Malaysia is fairly considerable as it has also been generally regarded as one of the major faults in the Peninsula.



7.3



STOP III DURIAN PERANGIN



Location: N 06⁰ 24’08.5” E 99⁰ 49’11.9”



This waterfall which has 14 tiers is located on the northern slope of Gunung Raya. Lithologically, the waterfall is made up of dark-grey banded hornfels. It is interpreted that this hornfels was formed as a result of contact metamorphic processes on the argillaceous rocks of the Singa Formation during the emplacement of the Gunung Raya granite.



7.4



STOP VI Kilim Jetty



Location: N 06° 24' 19.0" E 99° 51' 27.9"



The limestone is outcropping at the sea side. Everywhere it is characterized by rugged karst topography. This terrain in Langkawi is marked by abrupt and irregular slopes, cliffs and bare exposures of grey and white rock with numerous intervening hollows and valleys (Jones, 1978). Limestone are commonly composed of carbonate minerals e.g. calcite and dolomite. The solution process has obviously played an important role in the moulding of the carbonate rock’s surface to its present form. The marine erosion can be distinguished at the foot of the limestone cliffs and bears evidence of former higher sea-levels.



7.5



STOP V Pantai Pasir Hitam (Black Sand Beach)



Location: N 06° 25' 27.4" E 99° 47' 28.6"



This popular tourist spot is named after the black placer sands on the beach. The black sand is composed of mostly tourmaline with minor amounts of ilmenite and zircon derived from the eroding margins of the Raya Granite and concentrated by the repeated winnowing away of the lighter minerals such as quartz and micas or clays by the beach processes (Lee, 2002).



7.6



STOP VI Teluk Yu



Location: N 06⁰ 25’20.2” E 99⁰ 46’50.2”



The area is located at foothill of the Gunung Raya. The lithology is granite which is grey in colour with porphyritic texture.



The granite is rich in feldspar minerals with very coarse grained (> 1cm), which is considered as phenocryst and formed in darker-coloured groundmass. Xenolith (marked circle in the figure) is common in the granite which is fine-grained and grey in colour. The beach is rich with black sands (commonly tourmaline) which derived from Gunung Raya granite nearby.The weathering of the granite has produced elongated rock bodies.



7.7



STOP VII BUKIT MALUT



Location: N 06⁰ 17’43.8” E 99⁰ 47’16.4”



The outcrop of Bukit Malut is a slope cut. This location consists of mudstone which belongs to the Singa Formation. This mudstone had underwent contact metamorphism due to the heat from the granite intrusion, forming hornfels but still retaining its original sediment structure.



7.8



STOP VIII TELAGA TUJUH WATERFALL (SEVEN WELLS WATERFALL)



Location: N 06⁰ 22’57.9” E 99⁰ 40’23.2”



Telaga Tujuh composes of igneous rock (granite) which is located near to the boundary of Machinchang Formation Sandstone. The grain size of the granite ranges from medium to coarse. The phenocrysts are quite well arranged and might possibly indicate the direction of flow of magma during cooling process (Jones, 1978). The waterfall provides a superb section in the marginal granite over a 80 feet drop. The continuous expanse of massive, coarse-grained porphyritic granite has been smoothed by the flow of water and above the main falls a series of seven potholes has been eroded in the rock.



7.9



STOP IX PASIR TENGKORAK BEACH



Location: N 06⁰ 25’50.5” E 99⁰ 43’37.2”



Medium-grained sandstone with subordinate coarse-grained sandstone and shale are found here. The total thickness of the formation reaches up to 2,830 m (Lee, 1983). At this locality, the gently dipping and warping sandstone is part of the upper part of the Machincang Formation. The sandstone exhibits internal cross bedding and bedding-top ripple marks. Ball and pillow structures can also be observed. It formed due to the escaping mud, a unique end product from excessive loading of sand over water-saturated mud. Other sedimentary structures occurring at this locality are load cast, flame structure, convolute bedding and truncated sandstone lenses. Another unique feature here is tafoni structure which is a honeycomb-like structure formed by salt dessication, particularly on the exposed thick shale and fine-grained sandstone beds. Various shapes of the tafoni are controlled by the joint systems, fracture patterns and directions of the seasprays.