- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
Cleavage folding, flexure folding, and intrusion of granite sills in Cambrian and Ordovician-Silurian sediments are a result of the 'Langkawi folding phase'. This folding phase is dated as late Silurian-Devonian in age. A subphase can be discerned which has caused a deformation of the slaty cleavage in the areas showing slight regional metamorphism and a cross-folding in the areas which have only suffered flexure folding. The presence of an unconformity between Silurian and Carboniferous strata in Thailand and the presence of only a few scattered outcrops of Devonian strata in Malaya suggest that the Langkawi folding phase was not only active in the Langkawi islands but must have had a wider sphere of influence. A low-angle overthrust has been developed during post-Permian and pre-granitic time. This thrust is later arched by the granite intrusion during the Pacific orogeny.