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Curator of Micropalaeontology's blog

2 Posts tagged with the malaysia tag
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For obvious reasons I have always wanted to do fieldwork on Pulau Langgun, one of the islands that make up the Langkawi Islands off the far NW coast of the Malaysian Peninsula. In my last post I described the difficulties of interpreting the geology of the Malaysian Peninsula and how we were attempting to use conodont microfossils to answer some of the questions by dating the isolated rock exposures.

 

We travelled to Langkawi Island to sample conodonts from the most complete exposure of rocks in the region as it will act as a reference section for our student Atilia Bashardin and help to interpret the isolated rock exposures on the mainland. The islands are also where the conodont Panderodus langkawiensis was first described and this species was a target for our collecting.

 

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For two days our field vehicle (above) left us on the coastline early in the morning. The unfavourable tides meant that we only had three hours on the section before our boat had to come and pick us up.

 

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The early morning trip to the section was amazingly picturesque as we motored through mangroves and past imposing forested limestone crags. On the first morning we encountered dolphins as we moved out into the open water.

 

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This was our first sight of the study section from the sea. Initially it was difficult to see any rock exposures as they are hidden behind the margins of the forest that encroaches the beach. We landed at the end of the pier that you can see to the right and made our way along the coastline to the left.

 

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This is a typical limestone exposure in the area. Despite the idyllic setting, it is quite hard work to sample here. In my previous post I described how you usually need several kilogrammes of rock to find conodonts. Here the surfaces are very weathered leaving some beds standing proud. Unfortunately it is the recessed, weathered parts of the beds that we needed to collect as these will most easily dissolve in acetic acid (vinegar).

 

Microfossils can be recovered from most sedimentary rocks but it is important to choose the correct part of the rock to sample in order to maximise the yield. This often requires interpretation of the environment in which the rocks were originally deposited. It is not possible to know while sampling if a particular bed will yield conodonts and sometimes even an experienced eye can be wrong.

 

We are sampling here because these beds have previously yielded conodonts according to a paper published in the late 1960s and a recent study by a University of Birmingham undergraduate student.

 

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A scanning electron microscope image of an element from the apparatus of the conodont Panderodus langkawiensis recovered from one of the samples processed by John Lignum, former University of Birmingham undergraduate. The dotted scale bar at the bottom is 0.176mm.

 

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This is a rare blog picture of the 'Curator of Micropalaeontology' looking rather sweaty and muddy after an extended session with the geological hammer. The words on the pier behind say 'Teluk Mempelam' which means Mango Bay. Unfortunately there were no mangos to be seen.

 

In a 2005 paper published by two of my retired colleagues, Robin Cocks and Richard Fortey, the old name for the limestone here the 'Upper Setul Limestone Formation' was changed to the 'Mempelam Limestone Formation'. They studied the distribution of invertebrate fossils of this region, particularly the brachiopods and trilobites, to interpret the geological history of the region. Many of the collections that back up these findings are housed in the Museum.

 

Initial findings from the conodonts have provided more precise datings for some of the newly named geological formations suggested by Cocks and Fortey. It will also be interesting to see if the Mempelan Limestone Formation can be traced to the mainland.

 

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Not all the rocks on this coastal section were easy to swing a hammer at. Here Atilia is looking pleased with herself as she has managed to collect a nice lump of limestone from this rock exposure where previously I had failed! I had told her to give up but her persistence was rewarded.

 

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Here are two of our Mempelam Limestone Formation samples with a view of the section in the background.  These samples were too large to fit in our standard sample bags so we had to label them with indelible marker pen and carry them back to the boat by hand. The surface is pitted from weathering and some of the edges were quite sharp so they were quite difficult to carry.

 

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Dr Aaron Hunter (right) is pictured here with Universiti Teknologie PETRONAS undergradate student Vittaya Boon (left). He joined us on the trip as he is lucky enough to be doing his undergraduate project on Pulau Langgun, Langkawi. The two large cool boxes on the trolley were packed full of the limestone samples we collected.

 

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On the way home we gained a flat tyre and ended up having the valves on all four wheels replaced! Perhaps the extra loading from a heavy box of rocks caused this mishap? Emma and Aaron are seen here surveying the damage. A big thank you is due to Emma who drove us throughout the fieldtrip with an enormous amount of skill, concentration and patience.

 

The title of this blog was designed to make you want to read on and not meant to imply any slackness on our part . Hopefully over the last two blogs I have shown how conodonts can play a major role in Palaeozoic (roughly 500-200 million year old) geology by providing palaeotemperatures, palaeoenvironments and most importantly datings for rock successions. This fieldwork has also been an excellent example of the Museum developing links with international universities, providing teaching while expanding our collections from this geologically important region of the world.

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You may have noticed that I haven't posted regularly to my blog over the last couple of months and that's because I've been in Malaysia visiting my Masters student Atilia Bashardin at the Universiti Teknologie, PETRONAS, where I have just been appointed a visiting lecturer. This and the next two posts will be an annotated series of pictures covering my visit to Malaysia, fieldwork, the university and even a few pictures showing what a lucky geologist eats while they are in the field!

 

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Peninsular Malaysia does not, at first sight, look very promising for geologists as it is mainly flat, covered with palm oil plantations and paddy fields like this one above. Every now and again, amazing, imposing limestone hills rise from the flat landscape, while granites form a mountain backbone to the peninsular. As the granites formed beneath the surface of the earth, the heat given off metamorphosed the limestones, often turning them to marble. This gave them the hardness and resistance to erosion that causes them to stand out as we see them today.

 

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Because the limestone hills are geographically isolated from each other and heated to varying temperatures depending on proximity to the granites, it is difficult to work out if they relate to the same rock formations based soley on descriptions of the rocks exposed.

 

Knowing the relative ages of the hills and the distribution of rock formations present is vital for reconstructing the geological history of the area. The area surrounding the Malaysian peninsular has a complex geological history and now consists of roughly north-south trending major crustal units or terraines that docked together at various stages through geological time.

 

Studying conodonts from these limestones can help to date the rock formations, give an idea of the environments in which they were deposited and even suggest the maximum temperature to which they have been heated.

 

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It's important to be well fed while you are carrying out fieldwork. This curry lunch banquet above was served on a granite table lined with a bed of banana leaves. The food in this region is a delightful mix of Thai, Malay, Indian and Chinese, often combining these various tastes.

 

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PhD student Haylay Tsegab (right) is pictured above with his supervisor Dr Aaron Hunter (left), who was my host for the duration of the trip. Aaron has volunteered at the Museum and previously held a short term curatorial position in our Palaeontology Department (now part of Earth Sciences at the Museum). He is also co-supervisor of our Masters student Atilia Bashardin. Haylay is studying the carbonate sedimentology of some of the limestone hills in the Kinta Valley where the city of Ipoh is situated.

 

During our first day in the field we visited one of Haylay's study sites at Sungai Siput. Here they are going to drill a borehole through a section of relatively unmetamorphosed limestone. The digger behind them was used to clear the path to an old quarry so that the drilling equipment could be transported to the site.


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In the picture above, the hammer marks the approximate site where the borehole was due to be drilled a few days later. I took a sample for conodonts just to the left of the hammer in an attempt to date this succession of rocks that are believed to be Silurian age (approximately 415-440 million years old). I carried the 2kg sample home in my suitcase and it is now dissolving slowly in acetic acid (vinegar) in a lab down in the depths of the Palaeontology Building.

 

As well as dating the rock, it is hoped that the conodonts will be able to tell us the maximum temperature to which the rock has been heated: as conodonts are heated, they change from a pristine amber to black, grey and eventually white and these colour changes can be calibrated to show a maximum palaeo-temperature reading for the rock formation they came from. This is important as oil, gas and other minerals form under various temperature conditions.

 

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The limestone above has a large number of calcite veins running through it. The quarry was originally set up to provide ornamental stones like this one. Usually for a field picture like this, I would include a lens cap, coin or finger for scale. However, I didn't want to spoil this image so you will have to believe me that the field of view is approximately 20cm across.

 

The sample selected during field work contained as few calcite veins as possible because conodonts from these types of samples are likely to be fragmented due to the stresses and strains that the rocks have been subjected to. This section is important as it is relatively unmetamorphosed and early indications suggest that the limestone is black because of its high organic content. This, as well as its accessibility, is why this site has been chosen for drilling as part of Haylay's studies.

 

One of the questions remaining to be answered is whether these organic-rich-rocks are a potential source for hydrocarbons? The colour of any conodonts found should be able to tell us the answer to this. Malaysia's oil has been obtained from much younger rocks offshore to the east of peninsular Malaysia and North Borneo, not from the region we are studying. 

 

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The 'path' shown above is a typical limestone exposure reached after a drive north to Kg Ujung Bukit, Perlis. Here we took a sample for Atilia's M.Sc. project to study conodonts from Silurian rocks of the mainland and Langkawi Island. The rocks here have been given the same formation name as those exposed on Langkawi Island to the west. The fact that two different names have traditionally been given to this formation, the Setul Limestone Formation and the Mampelan Limestone Formation, shows some of the issues with interpreting the geology of the region.

 

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This is Aaron and Atilia after we had taken a sample of limestone that filled half of Atilia's rucksack. Usually conodont workers would take samples of at least a kilogramme in size and some have been known to take 50kg samples! Here we took about 5kg but didn't hang around for long after this picture was taken as we heard a snake in the undergrowth. We had probably disturbed it with our hammering!

 

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We followed up various reports of small quarries and rock exposures which led us to a small, shallow, disused quarry at the back of a house. The owners and their children were very interested to see why Atilia appeared to be trying to put piece of rock from their back garden into a plastic bag! While I was writing this blog post, I heard from Atilia that this sample has yielded some conodonts. Sometimes it can take weeks or months for samples to dissolve in weak acids, in this case, acetic acid. The tiny conodont elements then have to be picked out individually from under a microscope with a fine paint brush in the lab.

 

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Here we presumed that Atilia was trying to find out from the house owner if there are any more exposures of the limestone in the local area. Shortly after this, he led us to a quarry on his motorbike but sadly there was no limestone there. It may have already been quarried out. We did see some of the same rock lining a drainage ditch by the side of this road but resisted all temptation to sample it! It wouldn't have helped us as it was not part of an in-situ rock exposure so could have come from anywhere.

 

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Atilia demonstrating how to remain well covered up during mid-day fieldwork while carrying another limestone sample.

 

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It's important to remain hydrated while doing fieldwork in the humid conditions of South-East Asia. On most days there would be a large thunderstorm that cleared the air and, fortunately, we were never in the field during one of these. Most of these drinks shown above are iced water but usually we combined it with some lovely fruit juices and an occasional iced coffee. 

 

I have attempted to set the scene for some of the geological problems that we are hoping to solve using conodonts. My next post will detail our trip to Langkawi Island in search of yet more conodonts and hopefully more answers to our questions.



Giles Miller

Giles Miller

Member since: Apr 21, 2010

This is Giles Miller's Curator of Micropalaeontology blog. I make the Museum micropalaeontology collections available to visitors from all over the world, publish articles on the collections, give public talks and occasionally make collections myself.

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