Marginal basins of the SW Pacific and the preservation and recognition of their ancient analogues: a review

Leitch, E. C.

doi:10.1144/gsl.sp.1984.016.01.07

Cited by 18 publications

(3 citation statements)

References 73 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3), namely retreating and advancing (see Royden 1993b), based on their contrasting geological character, and modern examples from the eastern and western Pacific reflect a gross longterm kinematic framework with respect to an asthenospheric reference frame (Uyeda & Kanamori 1979;Dewey 1980;Lallemand et al 2008). Retreating orogens are undergoing long-term extension in response to lower plate retreat (trench rollback), with respect to the overriding plate (Royden 1993a), resulting in upper plate extension, including backarc basin opening as exemplified by the Tertiary history of the western Pacific (Taylor & Karner 1983;Leitch 1984;Schellart et al 2006). Advancing orogens develop in an environment in which the overriding plate is advancing towards the downgoing plate at a rate equal to, or greater than, the rate of lower plate slab retreat, and this results in overall upper plate compression (Lallemand et al 2005(Lallemand et al , 2008.…”

Section: Accretionary Orogen Typesmentioning

confidence: 99%

Accretionary orogens through Earth history

et al. 2009

View full text Add to dashboard Cite

Accretionary orogens form at intraoceanic and continental margin convergent plate boundaries. They include the supra-subduction zone forearc, magmatic arc and back-arc components. Accretionary orogens can be grouped into retreating and advancing types, based on their kinematic framework and resulting geological character. Retreating orogens (e.g. modern western Pacific) are undergoing long-term extension in response to the site of subduction of the lower plate retreating with respect to the overriding plate and are characterized by back-arc basins. Advancing orogens (e.g. Andes) develop in an environment in which the overriding plate is advancing towards the downgoing plate, resulting in the development of foreland fold and thrust belts and crustal thickening. Cratonization of accretionary orogens occurs during continuing plate convergence and requires transient coupling across the plate boundary with strain concentrated in zones of mechanical and thermal weakening such as the magmatic arc and back-arc region. Potential driving mechanisms for coupling include accretion of buoyant lithosphere (terrane accretion), flat-slab subduction, and rapid absolute upper plate motion overriding the downgoing plate. Accretionary orogens have been active throughout Earth history, extending back until at least 3.2 Ga, and potentially earlier, and provide an important constraint on the initiation of horizontal motion of lithospheric plates on Earth. They have been responsible for major growth of the continental lithosphere through the addition of juvenile magmatic products but are also major sites of consumption and reworking of continental crust through time, through sediment subduction and subduction erosion. It is probable that the rates of crustal growth and destruction are roughly equal, implying that net growth since the Archaean is effectively zero.Classic models of orogens involve a Wilson cycle of ocean opening and closing with orogenesis related to continent-continent collision. These imply that mountain building occurs at the end of a cycle of ocean opening and closing, and marks the termination of subduction, and that the mountain belt should occupy an internal location within an assembled continent (supercontinent). The modern Alpine -Himalayan chain exemplifies the features of this model, lying between the Eurasian and colliding African and Indian plates (Fig.

show abstract

Section: Accretionary Orogen Typesmentioning

confidence: 99%

Accretionary orogens through Earth history

et al. 2009

View full text Add to dashboard Cite

show abstract

“…The southwest Pacific, a vast region approximately the size of continental Australia, rapidly developed as an arc/back arc basin system over the last 100 Myr, behind the leading edge Tonga‐Kermadec volcanic arc [ Leitch , 1984]. Similarly, the Lachlan orogen began as a vast back arc basin system [ Collins and Vernon , 1992] which formed over a similar time span (530–440 Ma) before progressive closure, and probably originally was of similar ∼2000 km width, on the basis of estimates from palinspastic reconstructions [ Fergusson and Coney , 1992b].…”

Section: A Modern Analoguementioning

confidence: 99%

Nature of extensional accretionary orogens

2002

View full text Add to dashboard Cite

Extensional accretionary orogens form by creation and destruction of large arc/back arc basin systems, generated by extension and sediment infilling during prolonged slab retreat, but episodically thickened by basin inversion during short‐lived (∼10 Ma), orogenic contraction events. They are characterised by widespread, syntectonic, silicic, and minor basaltic magmatism, regional low‐P, variable‐T metamorphism, and by the enigmatic development of rift basins throughout the peak orogenic history. These orogens have features associated with retreating subduction boundaries and contrast markedly with those formed by terrane accretion, such as the Canadian Cordillera. The Paleozoic Lachlan orogen example from eastern Australia shows that Silurian‐Devonian synorogenic basalts and gabbros were intimately associated with rifting and granite emplacement, but they formed during a period of repeated orogenic contraction. Moreover, primitive basaltic compositions have oceanic affinities, indicating generation under lithosphere that was <30 km thick. Only in the final stages of orogeny (Middle Devonian), after at least three major crustal contraction events, did the lithosphere thicken to ∼80 km or more, leading to stabilization of the orogen. Extensional accretionary orogens grow by magmatic and sedimentary additions during extension, caused mainly by asthenospheric melting and rift basin formation/sedimentation, augmented by localized and repeated crustal thickening events. Orogenic contraction leaves an indelible structural imprint which may obliterate the prior‐formed extensional structures. The orogen remains hot, despite repeated thickening events, because of ongoing extension, which promotes advective heat transfer into the crust by basalt injection and crustal melting. Rapid switching to contraction, possibly during intermittent arrival of buoyant oceanic plateaus, inverts the thermally softened basins and forms localized fold‐thrust belts in which the penetrative foliations record the peak metamorphism. Their most diagnostic features are the presence of basaltic rocks and rift basins throughout the orogenic contraction history.

show abstract

“…Spreading half rates of Cenozoic-Recent back-arc basins range from 1-6 cm a" 1 (Leitch, 1984;Saunders & Tarney, 1984). This suggests 600-3600 km of extension in the Welsh Basin during the 30 Ma from the Llanvirn to Caradoc time.…”

Section: Discussionmentioning

confidence: 96%

Ordovician volcanism in the Welsh Borderland

Leat

Thorpe

1986

Geol. Mag.

View full text Add to dashboard Cite

Basaltic, andesitic and rhyodacitic/rhyolitic volcanism was widespread during Ordovician time in the Welsh Basin. New chemical data are presented for Llanvirn to Caradoc lavas and tuffs from the Welsh Borderland which, during Ordovician time, formed the southeastern margin of the Welsh Basin. In view of the observed chemical alteration, immobile elements are used in the interpretation of the original geochemical character. The data indicate that the Llanvirn Stapeley volcanic group of the Shelve inlier was a bimodal basalt/basaltic andesite – rhyodacite/rhyolite association. The basalts have trace element contents of tholeiitic associations with a subduction-related character. The Caradoc Whittery and Hagley volcanic groups of the Shelve inlier comprise lavas and tuffs of calc-alkaline andesite. Blocks sampled from the Breidden Hills show that these were also derived from a calc-alkaline volcano. Associated Caradoc pumice- and ash-flow deposits from the Breidden Hills are probably of altered calc-alkaline rhyodacite/rhyolite composition. The Sibdon Carwood basalt flow, the only known example of Ordovician volcanism east of the Pontesford–Linley and Church Stretton lineaments, has transitional tholeiitic to alkaline character, with trace element contents influenced by subduction-related processes. The overall tholeiitic to calc-alkaline nature of the magmatism is consistent with the view that, during Llanvirn to Caradoc time, the Welsh Basin was an ensialic marginal basin.

show abstract

Marginal basins of the SW Pacific and the preservation and recognition of their ancient analogues: a review

Cited by 18 publications

References 73 publications

Accretionary orogens through Earth history

Accretionary orogens through Earth history

Nature of extensional accretionary orogens

Ordovician volcanism in the Welsh Borderland

Contact Info

Product

Resources

About