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Alpine-Himalayan Orogens |
Department of Geology, Imperial College, Prince Consort Road, London S.W.7
The island of Sulawesi—formerly called Celebes—occupies a critical but very complex position at the junction of the Alpine-Himalayan and Circum-Pacific chains. It links along strike with both the Philippine and the Banda orogens, but lies between the Borneo and the West Irian orogens. The island is one of the most mountainous in the Indonesian Archipelago and is poorly known geologically, because of which the present article is largely in essay form.
Segment: the Sulawesi orogen has a strike length, excluding small Islands, of about 1300 km. The west margin of the belt consists of an arc open in the south to the south-east, which reverses its direction of curvature in the north to form an arc open to the north-west. In the south it is separated from the Sunda Shelf by the 2000 m deep Makassar Strait and in the north it is adjacent to the Celebes Sea. The east margin of the belt abuts against the Banggai and Sula Islands (part of a stable positive area called the Sula Spur) and, to the south, against the northern part of the Banda Sea. The width of the orogenic belt in Sulawesi, measured between these margins, varies from 500 km to 270 km, and averages 350 km.
History: the oldest rocks known in Sulawesi are sedimentary rocks which have been metamorphosed in pre-U. Triassic times. Then, there seems to have been a period of general uplift and erosion in Sulawesi. Mesozoic-Cenozoic orogenic movements commenced during U. Jurassic and L. Cretaceous times
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This 250-word extract was created in the absence of an abstract.
