On the supposed existence of the Kisap thrust in the Langkawi Islands, Northwest Peninsular Malaysia

Tan, B. K. (0981) On the supposed existence of the Kisap thrust in the Langkawi Islands, Northwest Peninsular Malaysia. Bulletin of the Geological Society of Malaysia, 14. pp. 127-133. ISSN 2637-109X

Abstract

The Kisap thrust in Langkawi is the only large thrust fault described in Peninsular Malaysia. Its existence has been accepted by several authors and it has frequently been cited as evidence in support of plate collision hypothesis. A re-examination of the evidence shows that there are many aspects of the proposed thrust fault that cannot be substantiated and that the existence of large scale thrusting in the area has yet to be proven. All the structures attributed to the proposed thrust movement occur either within rocks of the same formation or between conformable sequences. The strikes of the proposed fault planes and the adjacent beds are markedly different and the dips of the known fracture planes are too steep to be associated with low angle over-thrusting. Present knowledge of the geology of these islands indicates that the geological boundaries shown in published geological maps need to be revised. Correspondingly, the location of the proposed fault plane, if it is present, will be at some distance from the fault trace drawn in the maps. The nature of the contact between the Lower and Upper Palaeozoic rocks interpreted as a thrust in the eastern part of the Langkawi islands cannot be satisfactorily resolved at present.

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