• Economic and Environmental Geology
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• v.37 no.5
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• pp.437-457
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• 2004

The geology of the Kualakulun in the Middle Kalimantan, Indonesia comprises Permian to Carboniferous Pinoh Metamorphic Rocks and Cretaceous Sepauk Plutonics of the Sunda Shield, late Eocene Tanjung Formation, Oligocene Malasan Volcanics, Oligocene to early Miocene Sintang Intrusives and Quaternary alluvium. Tanjung Formation was deposited in low-and high-sinuosity channel networks developed on the proximal to distal delta plain and delta front forming southward paleoflow system, which, in turn, gradually change into shallow marine environment. Four main deformational phases are recognized: D1, folding of metamorphic rocks accompanied by development of S1 schistosity under regional metamorphic condition; D2, ductile shearing in Cretaceous granitoids; D3, folding of metamorphic rocks accompanied by S2 crenulation cleavage; D4, faulting under N-S compressional regime during Tertiary times, producing NE-trending sinistral and NW-trending dextral strike-slip faults and N-S to NNE-trending normal faults.