Kundasang (Sabah) at the intersection of regional fault zones of Quaternary age

702001-100503-301-B
Author : H.D. Tjia
Publication : Bulletin of the Geological Society of Malaysia
Page : 59-66
Volume Number : 53
Year : 2007
DOI : https://doi.org/10.7186/bgsm53200710

Bulletin of the Geological Society of Malaysia, Volume 53, June 2007, pp. 59 – 66

 

Kundasang (Sabah) at the intersection of regional fault zones of Quaternary age

H.D. Tjia

Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia


Abstract: The Crocker fault zone (CFZ) is more than 170 km long and several kilometres wide. It contains the Quaternary structural valleys Tenom, Keningau, and Tambunan which are aligned in a northerly to N20°E trend. Its most northern segment, Lobou-Lobou, displaced a tarred road for 15 cm left-laterally. In addition to normal faulting, as the association with valley-fill deposits suggests, tributaries of the Pegalan river that cross the CFZ boundary also display abrupt sinistral course shifts of several hundred metres. The Mensaban fault zone (MFZ) strikes WNW and is traceable over a distance of 110 km from Tuaran toward east into the interior of Sabah. Faceted ridge spurs indicate Quaternary activity of normal faulting with individual downthrows up to 50 m high. Along a Mensaban fault strand in the vicinity of Kundasang, the sudden course change of the Liwagu river suggests recent and sustained sinistral slip. In this area the MFZ is 12 km wide and intersects the CFZ. Continued activity on these two regional faults is one of the root causes of widespread mass movements in the Kundasang area.

 

Abstrak: Zon sesar Crocker dikesan sepanjang 170 km lebih dan selebar beberapa kilometer. Di dalamnya terkandung lembah struktur Tenom, Keningau dan Tambunan yang menjurus antara utara hingga U20°T. Ruas zon sesar paling utara, Lobou-Lobou, telah menganjak jalan berturap sebanyak 15 cm ke kiri. Bersamaan dengan sesaran menurun, seperti dicadangkan persekutuannya dengan isian sedimen Kuaterner lembah, sejumlah anak sungai kepada Sungai Pegalan ketika melintasi sesar sempadan lembah mengalami anjakan lateral sejauh beberapa ratus meter ke kiri. Zon sesar Mensaban berjurus timur-tenggara dan berpanjangan 110 km daripada Tuaran di barat ke arah pedalaman Sabah. Hujung rabung topografi yang berfaset mewakili aktiviti Kuaterner yang melibatkan sesaran menurun sehingga 50 m pada tempat tempat tertentu. Di sekitaran Kundasang, Sungai Liwagu tiba-tiba teranjak lateral ke kiri sejauh hampir 2 km. Zon sesar Mensaban berkelebaran 12 km. Di sana pula, kedua-dua sesar aktif serantau menyilang dan merupakan salah satu sebab utama kepada berlakunya susutan-darat yang meluas.

https://doi.org/10.7186/bgsm53200710


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