Topic
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.
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TL;DR: It is now generally accepted that Southeast Asia is composed of continental blocks which separated from Gondwana with the formation of oceanic crust during the Paleozoic, and were accreted to Asia in the Late Permian or Early Mesozoic.
Abstract: It is now generally accepted that Southeast Asia is composed of continental blocks which separated from Gondwana with the formation of oceanic crust during the Paleozoic, and were accreted to Asia in the Late Paleozoic or Early Mesozoic, with the subduction of the intervening oceanic crust. From east to west the Malay peninsula and Sumatra are composed of three continental blocks: East Malaya with a Cathaysian Permian flora and fauna; Sibumasu, including the western part of the Malay peninsula and East Sumatra, with Late Carboniferous–Early Permian ‘pebbly mudstones’ interpreted as glaciogenic diamictites; and West Sumatra, again with Cathaysian fauna and flora. A further unit, the Woyla nappe, is interpreted as an intraoceanic arc thrust over the West Sumatra block in the mid Cretaceous. There are varied opinions concerning the age of collision of Sibumasu with East Malaya and the destruction of Paleotethys. In Thailand, radiolarites have been used as evidence that Paleotethys survived until after the Middle Triassic. In the Malay peninsula, structural evidence and the ages of granitic intrusions are used to support a Middle Permian to Early Triassic age for the destruction of Paleotethys. It is suggested that the West Sumatra block was derived from Cathaysia and emplaced against the western margin of Sibumasu by dextral transcurrent faulting along a zone of high deformation, the Medial Sumatra Tectonic Zone. These structural units can be traced northwards in Southeast Asia. The East Malaya block is considered to be part of the Indochina block, Sibumasu can be traced through Thailand into southern China, the Medial Sumatra Tectonic Zone is correlated with the Mogok Belt of Myanmar, the West Burma block is the extension of the West Sumatra block, from which it was separated by the formation of the Andaman Sea in the Miocene, and the Woyla nappe is correlated with the Mawgyi nappe of Myanmar.
153 citations
01 Apr 2003
TL;DR: In this paper, U-Pb zircon data indicate that the earliest evidence of convergent magmatism along the northwest margin of the Borborema Province occurred around 777 Ma, and was followed by the development of a large continental arc batholith (Santa Quiteria batholith) between ca. 665 and 591 Ma within the central part of Ceara State.
Abstract: Recent field investigations and geochronological studies of Neoproterozoic rocks in the northwestern part of the Borborema Province, Ceara State, NE Brazil provide important clues pertaining to the nature of convergence between the Borborema Province and the West African-Sao Luis craton during the assembly of West Gondwana. U-Pb zircon data indicate that the earliest evidence of convergent magmatism along the northwest margin of the Borborema Province occurred around 777 Ma, and was followed by the development of a large continental arc batholith (Santa Quiteria batholith) between ca. 665 and 591 Ma within the central part of Ceara State. These findings, along with supporting geophysical data, suggest that convergence between the Borborema Province and the West African-Sao Luis craton involved closure of an oceanic realm with subduction polarity to the southeast beneath the northwestern part of the province. Consequently, it seems likely that the Pharusian Ocean was continuous from the Hoggar Province in West Africa into South America during the late Neoproterozoic and additional data suggests that it may have even been connected with the Goianides Ocean of the Brasilia Belt farther to the southwest.
152 citations
TL;DR: In this article, coupled climate-biome model simulations of the late Paleozoic were developed to determine the response of Pangean tropical climate to Gondwanan deglaciation.
Abstract: Coupled climate-biome model simulations of the late Paleozoic were developed to determine the response of Pangean tropical climate to Gondwanan deglaciation. The model simulations predict substantial changes over equatorial Pangea including continental drying, a reversal of equatorial winds, warming, heavier δ 18 O values of meteoric precipitation, and the expansion of deserts and the contraction of forests. The magnitude of these tropical responses is sensi- tive to the extent of Gondwana continental ice and the deglacial rise in atmospheric pCO 2 , boundary conditions that are not well known for the late Paleozoic. Nonetheless the model predictions are consistent with climatic and environmental trends determined from terrestrial proxy data, implying that the deglaciation of Gondwana was a transformational climate event in tropical Pangea.
152 citations
TL;DR: In this paper, two revised paleogeographic reconstructions of the Visean and Westphalian C-D stages are presented based on recent paleomagnetic, phytogeographic, stratigraphic, and tectonic data.
152 citations
TL;DR: The authors showed that the Falkland Islands have been rotated by 180° relative to South Africa and complements recent paleomagnetic data, indicating that the islands were originally part of South Africa.
Abstract: Stratigraphic and sedimentological fieldwork on the Falkland Islands confirms that they were originally part of South Africa. East and West Falkland have contrasting geological and deformation histories and are separated by the Falkland Sound fault, which marks a significant deformation edge to the Cape Fold Belt. The degree of structural deformation and metamorphism in West Falkland is substantially less than that of East Falkland, adjustments to differential shortening between the two islands being reflected by structures developed along the Falkland Sound fault. Prior to fragmentation of Gondwana, the Falkland Platform and Maurice Ewing Bank were positioned in the Natal Valley, adjacent to the east coast of South Africa. This predrift reconstruction shows that the Falkland Islands have subsequently been rotated by 180° relative to South Africa and complements recent paleomagnetic data. There was a complete overlap of the Maurice Ewing Bank and Falkland Platform to the exclusion of the Falkland Plateau Basin which is a small oceanic basin formed during the Jurassic fragmentation of Gondwana. Extension in this basin was accommodated by movements along the Aghulas Falkland Fracture Zone and the Gastre Fault System. Predrift restoration of these faults shows that Patagonia was positioned closer to both Africa and Antarctica. The Falkland Plateau Basin was an integral component of the West Gondwana Jurassic microplate system and provides an invaluable insight into the evolution of its western margin. At some time prior to the main opening of the South Atlantic, the Falkland Platform was rotated clockwise by 120° against the Agulhas Falkland Fracture Zone, such that the Falkland Islands were translated some 300 km to the south. The driving force for this rotation is not known but could possibly have been initiated by periodic stress buildups in the Falkland Plateau Basin as the Gastre Fault System, within continental crust, became unable to accommodate the continuous dextral shear in the Agulhas Falkland Fracture Zone. The Falkland Islands represent an outboard extension of the Eastern Cape and are significant for understanding the paleogeography of both the Cape and Karoo supergroups. East Falkland is closely similar to South Africa in its geology, while West Falkland shows significant contrasts with both the Devonian and Permian successions being more proximal in character but still demonstrate the eastward continuation of the Cape and Karoo basins.
152 citations