The Triassic Period was the first period of the Mesozoic Era and occurred between 251 million and 199 million years ago. It followed the great mass extinction at the end of the Permian Period and was a time when life outside of the oceans began to diversify.
At the beginning of the Triassic Period, the landmasses of the world were still bound together into the vast supercontinent known as Pangea. Pangea began to break apart in the Middle Triassic, forming Gondwana (South America, Africa, India, Antarctica, and Australia) in the south and Laurasia (North America and Eurasia) in the north. The movement of the two resulting supercontinents was caused by seafloor spreading at the midocean ridge lying at the bottom of the Tethys Sea, the body of water between Gondwana and Laurasia. While Pangea was breaking apart, mountains were forming on the west coast of North America by subduction of the ocean plates beneath the continental plates. Throughout the Middle to Upper Triassic, mountain-forming continued along the coast extending from Alaska to Chile. As mountains were forming in the Americas, North Africa was being split from Europe by the spreading rift. This division of the continents advanced further westward, eventually splitting eastern North America from North Africa.
Artist’s impression of what Singapore might have looked like looking north from the vicinity of Sentosa in the Late Triassic Period (200 Ma) before the mountains were eroded away to the low hills of the present time. The Bukit Timah Fault scarp and the Bukit Timah Granite and Gomback Gabbro form the mountains in the distance. In the foreground braided rivers drain into Lake Sentosa. The dinosaur in the front centre is the predator Coelophysis. Painted by W. Sillins. This is an excerpt from "A Field Guide To The Geology Of Singapore by Grahame J. H. Oliver and Avijit Gupta ".
The Belts
To understand the geology of Singapore, it is necessary to review the regional geology of the Malaysian Peninsula in terms of plate tectonic evolution. Linear belts of sedimentary and igneous rocks that run north northwest‒south southeast down the Malaysian Peninsula can be divided into three belts, namely the Eastern, Central and Western Belts.
The Eastern Belt
In eastern Johor in southern Peninsular Malaysia, fossiliferous Permian conglomerates unconformably overlie metamorphosed sandstone (quartzite) and mudstone (biotite schist) of the Mersing Beds which are assumed to be Carboniferous in age (350‒300 Ma1). Younger Permian (~300‒250 Ma) shallow water marine sediments and Permian to Middle Triassic (285‒240 Ma) andesitic volcanics and granites (with biotite and hornblende) are typical of those rocks found at modern active margins where subduction is occurring under volcanic arcs (e.g., as in the present day Andes or in the Sumatra–Java Volcanic Arc). The Eastern Belt is also called the Sukhothai Volcanic Arc which can be traced into Thailand and Cambodia. Permian fossil plants indicate equatorial affinities with Indochina. In Singapore, the boundary between the Central and Eastern Belts is marked by the Bukit Timah Fault
The Central Belt
The Central Belt contains thick sequences of fossiliferous shallow water marine Middle Permian to Middle Triassic (i.e., 275‒240 Ma) mudstones and limestones and associated andesitic volcanic and Andean-type granites similar to (and therefore a younger continuation of) those in the Eastern Belt Sukhothai Volcanic Arc. The Central Belt is distinguished from the Eastern Belt by having Late Triassic (i.e., 230‒200 Ma) continental red-bed deposits of sandstones and conglomerates.
The Western Belt
The Western Belt has a Cambrian (~500 Ma) to Middle Triassic (~240 Ma) marine sedimentary sequence including low latitude Permo-Carboniferous glacial marine beds. There is a notable lack of Permian volcanic activity in the Western Belt generally and no record of Late Triassic sedimentation. Fossils indicate cold water Gondwana Permian fauna in contrast to the equatorial Indochinese Permian fauna of the Eastern Belt. The Western Belt is thought to represent the passive continental margin of Gondwanaland. Granites in the Western Belt contain biotite and muscovite, similar to Himalayan continental collision granites and in contrast to the biotite-hornblende subduction zone granites in the Central and Eastern Belts. Western Belt granites are dated as Late Triassic (between 220‒200 Ma) and are therefore younger than the Central Belt granites (280‒220 Ma).
Documentation Progress
Above is a photogrammetry render of a rock sample taken from Dairy Farm. Approximately about 500 photos were taken to recreate this virtually. Photos were stitched in Agisoft Photoscan and then rendered in Unity. We wanted to test how these rocks would look like in Unity as we intend to recreate the space using the documented rocks as samples for our virtual environment.
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