East African Orogeny
The East African Orogeny (EAO) is the main stage in the Neoproterozoic assembly of East and West Gondwana (Australia–India–Antarctica and Africa–South America) along the Mozambique Belt.[2]
Gondwana assembly
The notion that Gondwana was assembled during the Late Precambrian from two older fragments along the Pan-African Mozambique Belt was first proposed in the early 1980s.[3] A decade later this continental collision was named the East African Orogeny, but it was also realised that this was not the simple bringing together of two halves. Rather, it was the piecemeal assembly of several much smaller cratonic elements that once formed an earlier supercontinent (today known as Rodinia), a process that eventually culminated in the relatively short-lived Gondwanan supercontinent.[2]
Two partly incomparable scenarios have been proposed for this assembly.
Erosion and Cambrian explosion
The East African orogeny resulted in the formation of an enormous mountain chain, known as the Transgondwanan Supermountain, which was more than 8,000 km (5,000 mi)-long and 1,000 km (620 mi)-wide. The sedimentary deposition from this mountain chain, known as the Gondwana Super-fan, exceeded 100 million cubic kilometres (24 million cubic miles) or the equivalent to covering the United States with c. 10 km (6.2 mi) of sediment, lasted for 260 million years and coincided with the
The orogen was eroded to such extent that by the Ordovician epoch it had been leveled to a planation surface in Ethiopia.[9][10]
Cenozoic reopening
The Cenozoic
References
- ^ Meert 2003, Fig. 10, p. 19
- ^ a b Stern 1994, pp. 320–321, 324
- ^ McWilliams 1981, Abstract
- ^ For a discussion see Meert 2003, Discussion, p. 31; Collins & Pisarevsky 2005, Comparisons with other models, pp. 256–257; Meert & Lieberman 2008, Assembling Gondwana: polyphase or simple?, pp. 9–11; Nance, Murphy & Santosh 2014, Pannotia (Gondwana), pp. 12, 14
- ^ Azania was defined by Collins & Windley 2002, Discussion, pp. 334–335 and named by Collins & Pisarevsky 2005, p. 244
- ^ Meert 2003, Abstract
- ^ Collins & Pisarevsky 2005, Comparisons with other models, pp. 256–257
- ^ Squire et al. 2006
- ISBN 978-94-017-8026-1.
- .
- ^ Ring 1994, Conclusions, p. 325
- ^ Aulbach, Rudnick & McDonough 2011, Geology and samples, pp. 106–108
Sources
- Aulbach, S.; Rudnick, R. L.; McDonough, W. F. (2011). Evolution of the lithospheric mantle beneath the East African Rift in Tanzania and its potential signatures in rift magmas. Vol. 478. pp. 105–125. )
- Collins, A. S.; Pisarevsky, S. A. (2005). "Amalgamating eastern Gondwana: The evolution of the Circum-Indian Orogens". Earth-Science Reviews. 71 (3–4): 229–270. .
- Collins, A. S.; Windley, B. F. (2002). "The tectonic evolution of central and northern Madagascar and its place in the final assembly of Gondwana" (PDF). The Journal of Geology. 110 (3): 325–339. hdl:2440/34282. Retrieved 6 January 2018.
- McWilliams, M. O. (1981). Palaeomagnetism and Precambrian tectonic evolution of Gondwana. Vol. 4. pp. 649–687. )
- Meert, J. G. (2003). "A synopsis of events related to the assembly of eastern Gondwana" (PDF). Tectonophysics. 362 (1): 1–40. . Retrieved 6 January 2018.
- Meert, J. G.; Lieberman, B. S. (2008). "The Neoproterozoic assembly of Gondwana and its relationship to the Ediacaran–Cambrian radiation". S2CID 2814283.
- Nance, R. D.; Murphy, J. B.; Santosh, M. (2014). "The supercontinent cycle: a retrospective essay". Gondwana Research. 25 (1): 4–29. .
- Ring, U. (1994). "The influence of preexisting structure on the evolution of the Cenozoic Malawi rift (East African rift system)". Tectonics. 13 (2): 313–326. . Retrieved 6 January 2018.
- Squire, R. J.; Campbell, I. H.; Allen, C. M.; Wilson, C. J. (2006). "Did the Transgondwanan Supermountain trigger the explosive radiation of animals on Earth?" (PDF). Earth and Planetary Science Letters. 250 (1): 116–133. . Retrieved 11 September 2017.
- Stern, R. J. (1994). "Arc assembly and continental collision in the Neoproterozoic East African Orogen: implications for the consolidation of Gondwanaland" (PDF). . Retrieved 6 January 2018.