Gondwana

About: Gondwana is a research topic. Over the lifetime, 6078 publications have been published within this topic receiving 263050 citations. The topic is also known as: Gondwanaland.

Late Permian to Late Triassic palaeomagnetic data from Iran: constraints on the migration of the Iranian block through the Tethyan Ocean and initial destruction of Pangaea

Abstract: SUMMARY A palaeomagnetic study of Late Permian to early Jurassic rocks from the Alborz and Sanandaj‐Sirjan zones in Iran and a compilation of selected palaeopoles from the Carboniferous to the present provide an updated history of the motion of the Iranian block within the Tethys Ocean. The Iran assemblage, part of Gondwana during the Palaeozoic, rifted away by the end of the Permian. We ascertain the southernhemisphere palaeoposition of Iran at that time using magnetostratigraphy and show that it was situated close to Arabia, near to its relative position today. A northward transit of this block during the Triassic is shown, with an estimated expansion rate of the Neotethyan ridge of 100‐140 km Myr’1. The northward convergence with respect to Eurasia ended during the Ladinian (Middle Triassic), and is marked by a collision in the northern hemisphere with the Turan platform, which was the southern margin of the Eurasian continent at that time. No north‐south component of shortening is evidenced north of Iran afterwards. An analysis of the declinations from the Late Permian to the present shows diVerent, large rotations, emphasizing the important tectonic phases suVered since the Triassic. Finally, we propose palaeomagnetic reconstructions of the Tethys area during the Late Permian and the Late Triassic, showing that the Palaeotethys Ocean was narrower than previously thought, and did not widen its gate to the Panthalassa before the Triassic period.

Drainage evolution in south-central Africa since the breakup of Gondwana

Abstract: The drainage system in south-central Africa has undergone major reorganisations since the disruption of Gondwana. Isopachs of the Kalahari sequence and a variety of geomorphological features can be used to pinpoint abandoned drainage lines. Continental fluvial sediments of Mesozoic-Cenozoic age reflect river systems which existed prior to and immediately following continental break-up. The east coast sedimentary sequence documents changes in the location of major supplies of terrigenous sediments, and provides a framework for establishing the timing of changes in drainage configuration. This evidence indicates that during the upper Jurassic to Cretaceous, the Okavango, Cuando and Zambezi-Luangwa rivers formed the headwaters of the proto-Limpopo. The lower-Zambezi-Shire formed a separate graben-bound river system with a discharge point into the Indian Ocean in the vicinity of mouth of the present-day Zambezi. A third major drainage entered the Indian in the vicinity of the modern Save mouth. End Cretaceous uplift along the Okavango-Kalahari-Zimbabwe Axis severed the links between the Limpopo and the Okavango, Cuando and Zambezi-Luangwa. This resulted in a senile endoreic drainage system which supplied sediment to the Kalahari basin. However, the uplift rejuvenated the lower Zambezi, initiating headward erosion and progressive capture of the Luangwa, upper Zambezi and Kafue. Predatory headward extension of the Zambezi is still active, and this river will eventually capture the Okavango. The model developed for drainage reorganisation provides a framework for interpreting kimberlitic heavy mineral dispersion patterns. It also forms the basis for explaining fish and plant dispersion patterns, and understanding recent water level fluctuations in the Makgadigadi pans system in Botswana.

Geological History of Britain and Ireland

Abstract: Part I: Introduction:. 1. Regional Geological History: Why And How:N. H. Woodcock & R. A. Strachan. 2. Geological Framework Of Britain And Ireland: R. E. Holdsworth, N. H. Woodcock & R. A. Strachan. Part II: The Northern Margin Of The Iapetus Ocean:. 3. Early Earth History And Development Of The Archaean Crust: R. A. Strachan. 4. Proterozoic Sedimentation, Orogenesis And Magmatism On The Laurentian Craton: R. A. Strachan & R. E. Holdsworth. 5. Late Neoproterozoic To Early Ordovician Passive Margin Sedimentation Along The Laurentian Margin: R. A. Strachan & R. E. Holdsworth. 6. The Grampian Orogeny: Mid-Ordovician Arc-Continent Collision Along The Laurentian Margin: R. A. Strachan. 7. Mid-Ordovician To Silurian Sedimentation And Tectonics On The Northern Active Margin Of Iapetus: R. A. Strachan. Part III: The Southern Margin Of The Iapetus Ocean:. 8. Neoproterozoic To Cambrian Accretionary History Of Eastern Avalonia And Armorica: R. A. Strachan. 9. The Cambrian And Earliest Ordovician Quiescent Margin Of Gondwana: N. H. Woodcock. 10. Ordovician Volcanism And Sedimentation On Eastern Avalonia: N. H. Woodcock. 11. Late Ordovician To Silurian Evolution Of Eastern Avalonia During Convergence With Laurentia: N. H. Woodcock. Part IV: The End Of The Iapetus Ocean:. 12. The Caledonian Orogeny: A Multiple Plate Collision: N. H. Woodcock & R. A. Strachan. 13. Devonian Sedimentation And Volcanism On The Old Red Sandstone Continent: N. H. Woodcock. Part V: The Variscan Cycle: Consolidation Of Pangaea:. 14. Carboniferous Sedimentation And Volcanism On The Laurussian Margin: P. D. Guion, P. Gutteridge & S. J. Davies. 15. The Variscan Orogeny: The Welding Of Pangaea: L. N. Warr. Part VI: Post-Variscan Intraplate Setting:. 16. Permian To Late Triassic Post-Orogenic Collapse And Early Atlantic Rifting: A. H. Ruffell & R. G. Shelton. 17. Late Triassic To Jurassic: The Beginning Of The End For Pangaea: S. P. Hesselbo. 18. Early Cretaceous: Rifting And Sedimentation Before The Flood: A. S. Gale. 19. Late Cretaceous To Early Tertiary Deposition Through The Global Highstand: A. S. Gale. 20. Tertiary Events: The North Atlantic Plume And Alpine Pulses: R. Anderton. 21. The Quaternary: The History Of An Ice Age: N. H. Woodcock