Continental fragment

About: Continental fragment is a research topic. Over the lifetime, 119 publications have been published within this topic receiving 8859 citations. The topic is also known as: microcontinent.

Towards a paleogeography and tectonic evolution of Iran

Abstract: Maps of the paleography of Iran are presented to summarize and review the geological evolution of the Iranian region since late Precambrian time On the basis of the data presented in this way reconstructions of the region have been prepared that take account of the known major movements of continental masses These reconstructions, which appear at the beginning of the paper, show some striking features, many of which were poorly appreciated previously in the evolution of the region They include the closing of the 'Hercynian Ocean' by the northward motion of the Central Iranian continental fragment(s), the apparently simultaneous opening of a new ocean ('the High-Zagros Alpine Ocean') south of Iran, and the formation of 'small rift zones of oceanic character' together with the attenuation of continental crust in Central IranWith the disappearance of the Hercynian Ocean, the floor of the High-Zagros Alpine Ocean started to subduct beneath southern Central Iran and apparently disappeared by Late Cretaceou

South China in Rodinia: Part of the missing link between Australia–East Antarctica and Laurentia?

Abstract: Stratigraphic correlations and tectonic analysis suggest that the Yangtze block of South China could have been a continental fragment caught between the Australian craton and Laurentia during the late mesoproterozoic assembly of the supercontinent Rodinia. The Cathaysia block of southeast China may have been part of a 1.9–1.4 Ga continental strip adjoining western Laurentia before it became attached to the Yangtze block around 1 Ga. This configuration provides a western source region for the clastic wedges in the Belt Supergroup of western North America which contain detrital grains of 1.8–1.6 Ga and 1.22–1.07 Ga. The breakup of Rodinia around 0.7 Ga separated South China (Yangtze plus Cathaysia blocks) from the other continents.

North Palawan Block, Philippines--Its Relation to Asian Mainland and Role in Evolution of South China Sea

Abstract: The Island of Mindoro, the northern part of Palawan Island, and the Reed Bank area (southwestern Philippines) together constitute a continental fragment, the North Palawan block, lying within an island arc-oceanic setting. The Permian to Paleogene rocks of these areas indicate a geologic origin and history for the block contrasting with that of the rest of the Philippine Archipelago. These rocks also suggest that the North Palawan block once occupied a pre-drift position contiguous with the south China mainland. Four prominent pre-Neogene regional unconformities are recognized both onshore and offshore the China mainland, in Taiwan, and in the North Palawan block. The synchrony of these unconformities and the facies relation of the unconformity-bounded sedimentary units strongly suggest a common pre-Neogene history for all these areas. By contrast, an important regional unconformity, occurring at the top of the middle Miocene throughout the Palawan area, is absent from the Asian mainland. Extension in the South China Sea basin since the Mesozoic, which has separated the North Palawan block from the Asian mainland, has been approximately uniform from west to east. However, there is strong evidence to suggest that this extension has been achieved by temporally separated phases of continental crustal attenuation and more recent sea-floor spreading. From the foregoing observations and using the most recent magnetic spreading anomaly data for the South China Sea, a suite of palinspastic reconstructions has been prepared, which shows the evolution of the South China Sea area from the Late Triassic to the Pliocene. The reconstructions illustrate (1) the convergent continental margin setting of the North Palawan block during much of the Jurassic and Cretaceous; (2) the Late Cretaceous inception of the Philippine island-arc system; (3) the subsequent counter-clockwise rotation of the arc system from the late Eocene onward; (4) the Paleocene to middle Miocene opening of the South China Sea; and (5) the early to middle Miocene collision between the North Palawan block and the Palawan subduction system.

Opening mode of the Japan Sea inferred from the palaeomagnetism of the Japan Arc

Abstract: The western edge of the Pacific plate is marked by a chain of back arc basins stretching from the Aleutians, through Japan and the Philippines to New Zealand. Most of the basins lie behind volcanic island arcs far from continents and are the result of extension of the oceanic lithosphere1. But the Japan Sea is bounded on one side by continental crust (the Sikhote Alin and Korean Peninsula of the Asian continent) and on the other by an active arc with continental fragments. It can thus be said to be associated more with continental rifting1–4 than with oceanic processes. We report here palaeomagnetic data from the Japan arc which indicate that, since the early Miocene, north-east Japan has rotated counter-clockwise through 47° around a vertical axis while south-west Japan has rotated clockwise through 56° (refs 5–8). We attribute this differential rotation, which took place concurrently between 21 and 11 Myr ago, to the back arc opening of the Japan Sea8 with a ‘double-door’ mode, that is, there are two fan-shaped spreading basins facing each other. Such a fan-shaped opening is probably peculiar to the geological phenomenon of rifting of a continental fragment from thick continental lithosphere.