Kota Kinabalu, Sabah: A Turbidite Paradise

Kota Kinabalu, the largest town in Sabah, Borneo, is a rapidly developing urban centre and a tourist attraction in South East Asia. To the geologist, this part of Sabah is also renowned for its outcrops of turbidites. These Oligocene deepwater sediments are among the most sand-rich turbidite outcrops in the world.
This article appeared in Vol. 8, No. 5 - 2012


The Land below the Wind

A view of turbidites of the West Crocker Formation in Kota Kinabalu. The author, seen in the photo for the scale, is looking at a small normal slip fault that has slightly deformed the interbedded sandstone and shale beds. Photo: Rasoul Sorkhabi Kota Kinabalu is a rapidly developing city for touristic, commercial and industrial reasons. Photo: Rasoul Sorkhabi Sabah is known as ‘the Land below the Wind’ because it lies below the typhoon (hurricane) belt. Land Below the Wind (1939) is also the title of a classic work on the cultural and natural setting of Sabah from the pen of a lady writer, Agnes Newton Keith (1901-1982), who lived there in the first half of the 20th century. Her husband Henry “Harry” worked as Conservator of Forests and Director of Agriculture for the British government of North Borneo, now known as Sabah.  

Located on the north-west corner of Borneo, Kota Kinabalu (abbreviated as KK) is the capital of the Sabah state in East Malaysia. With a population of about 900,000, the greater KK is the sixth largest metropolis in Malaysia. Although its people speak Bahasa Malaysia, there are many different ethnic and linguistic groups, including Kadzan-Dusan, Bajau, Malay, Murut and Chinese (Hakka). KK has a fairly large airport that provides domestic flights (to Kuala Lumpur, Kuching and elsewhere in Malaysia) as well direct flights to overseas destinations in Brunei, Seoul, Shanghai, Hong Kong, Taipei, Singapore, Manila and Tokyo.  

Seafood lovers will find numerous restaurants both in downtown KK and along its shores which offer diverse, fresh and inexpensive seafood. The University of Malaysia Sabah, founded in 1994 in KK, has a large campus on a hill facing the South China Sea. The city has a warm, humid climate typical of the equatorial region.

Api Api to Kota Kinabalu

A view of the upper shale unit of the West Crocker turbidites in KK. Photo: Rasoul Sorkhabi  Source: Rasoul Sorkhabi KK’s history is a blend of ancient and colonial heritage. In pre-modern times, it was a small fishing village called Api Api (“fire, fire”) after the fireflies which twinkle on local mangrove trees at night. In 1882, the British Chartered (North Borneo) Company established a settlement on Gaya Island (Pulau Gaya) offshore the present city of KK. In 1888, the British declared North Borneo (Sabah) as a protectorate of the United Kingdom. However, the indigenous people of Bajau, led by their leader Mat Salleh, burned the colonial settlement on Gaya Island in 1897, and the British then moved their settlement to Api Api. The new place was renamed Jesselton after Sir Charles Jessel (1860-1928) who was then the Vice-President of the Company which played a leading role in the early development of the city.  

During World War II, Sabah came under Japanese rule, and after the war ended in 1945, North Borneo became a British Crown Colony. In 1963, the region gained self-government and joined the Federation of Malaysia. The name Kota Kinabalu then replaced Jesselton; it was so named because Mount Kinabalu, a granite massif 4,101m high, is located about 90 km north-east of the city.  

In 1976, the government of Sabah allowed Malaysia’s national oil company Petronas to explore its offshore territory in exchange for royalties. In recent years, several international oil companies have also operated offshore Sabah with notable deepwater discoveries.

The Turbidites of the Crocker Range

Facing the western waters, KK offers splendid views of sunsets over the offshore islands. Source: Rasoul Sorkhabi Sabah Museum in KK offers an excellent opportunity to gain visual knowledge of the history and culture of peoples who have settled Sabah for millennia. Source: Rasoul Sorkhabi A simplified palaeotectonic map of Borneo during the Oligocene. The Crocker Formation was deposited as deepwater (foredeep) fan sediments facing a subduction zone on the South China Sea. Prior to this event, a subduction zone existed along the Rajang-Kalimantan line during the Paleocene followed by the continental collision of the Luconia Block (which had drifted away from Sundaland) with Borneo (Kalimantan) during the Eocene. Source: Rasoul Sorkhabi The landscape of KK forms the foothill part of the Crocker Range. A remarkable geologic feature of this area in western Sabah is the wide distribution of turbidites of the Crocker Formation. These are interbedded sandstone and shale sedimentary rocks deposited in a deepwater basin (submarine fan) during the latest Eocene (37 Ma) through to the earliest Miocene (21 Ma).  

The Crocker Range runs north-north-east to south-south-west and is deformed by a series of high-angle reverse faults dipping south or south-east; therefore, the turbidite packages exhibit repeated stratigraphy across the region, making their measurement a difficult task. The reverse faults probably formed during the Miocene, and the soft shale layers have often acted as slip planes for the faults and deformation.  

The turbidites probably reach a thickness of 1,000m. Felix Tongkul, a geology professor at the University of Malaysia Sabah, who conducted his doctoral research in this area, has divided the turbidites into the lower sandstone unit (several hundreds of metres thick) and the upper shale unit (about 100m thick). The lower sandstone unit is an alternation of thick grey sandstone beds and relatively thin shale beds. The sandstone is quartz rich, and the individual beds range from tens of centimetres to a few metres thick. The upper shale unit has much thinner sandstone layers and occurs as a cap rock of grey or red shale. The Crocker turbidites are also exposed on islands offshore KK, and extend offshore western Sabah below the Miocene-Quaternary deltaic sediments, but these Oligocene turbidities have not yet been explored for their possible gas resources.

The Crocker Formation turbidites sit on the Eocene Trusmadi Formation (thick dark shale beds interbedded with thin sandstone layers). The relationship between the two formations is probably an unconformity. The basement rock of this part of Sabah is an ophiolite mélange (ocean-floor subduction rocks), probably of Cretaceous age.  

For turbidite lovers, KK is a paradise, as one can visit numerous sections of the West Crocker Formation, among the most sand-rich turbidite outcrops in the world, along the roads within and outside the city. If you plan to visit KK for this purpose, I recommend the following two papers for more information:  

Felix Tongkul (1989) “The sedimentology and structure of the Crocker Formation in the Kota Kinabalu area,” GEOSEA VI Proceedings, Jakarta 1987, Indonesian Association of Geologists, pp. 135-156.  

Paul D. Crevello et al. (2006) “Mixed braided and leveed-channel turbidites, West Crocker fan system, northwest Borneo,” in Atlas of Deep-Water Outcrops, AAPG Studies in Geology 56.


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