Cimmeria (continent)

Cimmeria was an ancient continent or terrane that rifted from Gondwana during the Permian. Cimmeria consisted of parts of Turkey, Iran, Afghanistan, Tibet (Qiang Tang and Lasa), Shan–Thai, and Malaya.^[1] Cimmeria was on the Cimmerian Plate, an ancient tectonic plate that was subducting under Asia.

Origin of concept[edit]

After extensive field work in the Middle East, Stöcklin 1974 identified the northern foot of the Alborz Range in northern Iran as the suture which in the Paleozoic was the northern shore of Gondwana and the remains of Paleo-Tethys Ocean. Stöcklin also noted that an early Mesozoic or late Paleozoic rift separated the Iranian Plate from the Arabian Plate, and that another southern suture must be the remains of the Neo-Tethys Ocean. The opening of this later ocean, Stöcklin realized, must have transformed Iran into a microcontinent. Those observations made Stöcklin the first to identify a small part of what would later be known as Cimmeria. Stöcklin also noted that his proposal resembled the old concept of the world in which there were two continents, Angaraland in the north and Gondwana in the south, separated by an elongated ocean, the Tethys. Iran belonged to neither continent but was part of the realm of Tethys.^[2]

Stöcklin's southern suture was later confirmed by observations of the evolution of microflora in Iran; which during the Carboniferous had Gondwanan but during the Late Triassic had Eurasian affinities — Iran had clearly drifted from Gondwana to Laurasia.^[3]

Şengör 1984, 1987 extended Stöcklin's Iranian microcontinent further west to Turkey and further east to Tibet and the Far East. Şengör also reused the name introduced by Suess 1901, the "Cimmerian Mountains".^[3]^[4]

Tectonic history[edit]

Cimmeria rifted from the Gondwanan shores of the Paleo-Tethys Ocean during the Carboniferous-earliest Permian and as the Tethys Ocean opened behind it during the Permian the Paleo-Tethys closed in front of it.^[5] During the Early and Middle Palaeozoic Cimmeria underwent an Andean-style active margin. Glacial deposits and paleomagnetic data indicate that Qiang Tang and Shan Thai-Malaya were still located far south adjacent to Gondwana during the Carboniferous. The equatorial fauna and flora of China indicate that it was separated from Gondwana during the Carboniferous. Cimmeria crossed the Paleo-Tethys Ocean in the Late Paleozoic and eventually collided with the southern margin of the Siberian continent during the Middle to Late Triassic Cimmerian Orogeny.^[1]

Economic importance[edit]

The present remains of Cimmeria, as a result of the massive uplifting of its continental crust, are unusually rich in a number of rare chalcophile elements. Apart from the Altiplano in Bolivia, almost all the world’s deposits of antimony as stibnite are found in Cimmeria, with the major mines being in Turkey, Yunnan and Thailand. The major deposits of tin are also found in Malaysia and Thailand, whilst Turkey also has major deposits of chromite ore.

References[edit]

Notes

^ ^a ^b Scotese & McKerrow 1990, pp. 4, 5, 17
^ Stöcklin 1974, Introduction, p. 873
^ ^a ^b Stampfli 2000, Some definitions, pp. 1–2
^ Şengör et al. 1988, pp. 119–120
^ Golonka 2007, p. 182

Sources

Golonka, J. (2007). "Phanerozoic paleoenvironment and paleolithofacies maps: late Palezoic". Geologia 33 (2): 145–209. Retrieved June 2016.
Scotese, C. R.; McKerrow, W. S. (1990). "Revised world maps and introduction" (PDF). Geological Society, London, Memoirs 12 (1): 1–21. Retrieved June 2016.
Şengör, A. M. C. (1984). "The Cimmeride orogenic system and the tectonics of Eurasia". Geological Society of America Special Papers 195: 1–74. doi:10.1130/SPE195-p1. ISBN 9780813721958.
Şengör, A. M. C. (1987). "Tectonics of the Tethysides: orogenic collage development in a collisional setting". Annual Reviews of Earth and Planetary Science 15: 213–244. doi:10.1146/annurev.ea.15.050187.001241. Retrieved June 2016.
Şengör, A. M. C.; Altıner, D.; Cin, A.; Ustaömer, T.; Hsü, K. J. (1988). "Origin and assembly of the Tethyside orogenic collage at the expense of Gondwana Land" (PDF). Geological Society, London, Special Publications 37 (1): 119–181. Retrieved June 2016.
Stampfli, G. M. (2000). "Tethyan oceans" (PDF). Geological society, London, special publications 173 (1): 1–23. Retrieved June 2016.
Stöcklin, J. (1974). "Possible Ancient Continental Margins in Iran". In Burk, C. A.; Drake, C. L. The geology of continental margins. Springer Berlin Heidelberg. pp. 873–887. Retrieved June 2016.
Suess, E. (1901). Der Antlitz der Erde (in German) 3. Wien F. Tempsky. Retrieved October 2015.