Geology of Singapore

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Sajahat Formation

Sajahat Formation (probably about 500 to 450 m.y.) comprises metasedimentary rocks including quartzite, quartz sandstone and mudstones. The formation was deposited in a shallow marine environment of ancient ocean, the Yunnan-Malay Basin, which during the Paleozoic era stretched along the eastern margin of the Gondvana Land, and was part of the Palaeo-Tethys Ocean. The final collision of continental plates, and closure of Palaeo-Tethys was probably in the Late Triassic during the Indosinian Orogeny (Oliver and Prave 2013).

The age of deposits is uncertain, although the oldest rocks in the Yunnan-Malay Basin date back to the Late Cambrian (the Gunung Matchincang Formation including similar rocks) and are now exposed near the Langkawi Islands. The subsidence of the oceanic plate was related to its westward movement towards the Precambrian craton, i.e. the Variscan subduction zone which existed from the Late Devonian to the Permian (Hutchinson 1973).

It is however also possible that the age of Sahajat formation is Late Paleozoic or even Triassic.

Literature

Foo, K.Y., 1983. The Palaeozoic sedimentary rocks of Peninsular Malaysia—Stratigraphy and Correlation, Workshop on Stratigraphic Correlation of Thailand and Malaysia
Hutchison C.S. 1973. Tectonic Evolution of Sundaland: A Phanerozoic Synthesis, Geological Society of Malaysia, Bulletin
Hutchison C.S. (ed.) 2014. Geology of Peninsular Malaysia, Publications of the Geological Society of Malaysia
Stauffer P.H. 1974 Malaya and Southeast Asia in the pattern of continental drift, Geological Society of Malaysia, Bulletin