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A terrane in geology, in full a tectonostratigraphic terrane, is a fragment of crustal material formed on, or broken off from, one tectonic plate and accreted or "sutured" to crust lying on another plate. The crustal block or fragment preserves its own distinctive geologic history, which is different from that of the surrounding areas—hence the term "exotic" terrane. The suture zone between a terrane and the crust it attaches to is usually identifiable as a fault. A sedimentary deposit that buries the contact of the terrane with adjacent rock is called an overlap formation. An igneous intrusion that has intruded and obscured the contact of a terrane with adjacent rock is called a stitching pluton. Older usage of ''terrane'' simply described a series of related rock formations or an area having a preponderance of a particular rock or rock groups.

Overview

A tectonostratigraphic terrane is not necessarily an independent microplate in origin, since it may not contain the full thickness of the lithosphere. It is a piece of crust which has been transported laterally, usually as part of a larger plate, and is relatively buoyant due to thickness or low density. When the plate of which it was a part subducted under another plate, the terrane failed to subduct, detached from its transporting plate, and accreted onto the overriding plate. Therefore, the terrane transferred from one plate to the other. Typically, accreting terranes are portions of continental crust which have rifted off another continental mass and been transported surrounded by oceanic crust, or they are old island arcs formed at some distant subduction zone. A tectonostratigraphic terrane is a fault-bounded package of rocks of at least regional extent characterized by a geologic history which differs from that of neighboring terranes. The basic characteristics of these terranes is that the present spatial relations are not compatible with the inferred geologic histories. Where terranes which lie next to each other possess strata of the same age, it must be demonstrable that the geologic evolutions are different and incompatible, and there must be an absence of intermediate lithofacies which could link the strata. The concept of ''tectonostratigraphic terrane '' developed from studies in the 1970s of the complicated Pacific Cordilleran orogenic margin of North America, a complex and diverse geological potpourri that was difficult to explain until the new science of plate tectonics illuminated the ability of crustal fragments to "drift" thousands of miles from their origin and fetch up, crumpled, against an exotic shore. Such terranes were dubbed "accreted terranes" by geologists. When terranes are composed of repeated accretionary events, and hence are composed of subunits with distinct history and structure, they may be called superterranes.

Tectonostratigraphic terranes

Africa *Birminian Terrane *Kahiltna Terrane *Likasi Terrane *Mozambique Belt Asia *Aldan Terrane *Bargusin Terrane *Daldyn Terrane *Magan Terrane *Markha Terrane *Shan–Thai Terrane *Tungus Terrane *Tynda Terrane *Uchur Terrane Taiwan *Coastal Range Terrane *Longitudinal Valley Terrane *Eastern Central Range Terrane *Western Central Range Terrane *Hsuehshan Range Terrane *Western Foothills Terrane *Coastal Plain Terrane Tibet *Lhasa TerraneAitchison, J. C., Ali, J. R., and Davis, A. M. (2007) "When and where did India and Asia collide?" ''Journal of Geophysical Research'', v.112, pp.1–19 *Qiangtang Terrane *Xigaze Terrane *Bainang Terrane *Zedong Terrane *Dazhuqu Terrane Australasia *Brook Street Terrane *Buller Terrane *Caples Terrane *East Tasmanian Terrane *Glenburgh Terrane *Dun Mountain-Maitai Terrane *Molong—Monaro Terrane *Murihiku Terrane *Narryer Gneiss Terrane *Takaka Terrane *Torlesse Composite Terrane *Waipapa Composite Terrane *West Tasmanian Terrane Europe *Armorican terrane *Avalonia *Avalon Composite Terrane *Balearic Terrane *Briançonnais Terrane *Central Highlands Terrane *Central Southern Uplands Terrane *Charnwood Terrane *Hebridean Terrane *Leinster—Lakesman Terrane *Midland Valley Terrane *North Armorican Composite Terrane *Northern Highlands Terrane *Rosslare—Monian Terranes *Southern North Sea Terrane *Tregor—La Hague Terrane *Wrekin Terrane Fennoscandia *Bamble Terrane *Idefjorden Terrane *Kongsberg Terrane *Telemarkia Terrane *Western Gneiss Region North America *Avalonia Terrane *Bancroft Terrane *Buffalo Head Terrane *Cache Creek Terrane *Carolina Terrane *Cassiar Terrane *Crescent Terrane *Elzevir Terrane *Frontenac Terrane *Ganderia Terrane *Hottah Terrane *Insular Superterrane *Meguma Terrane *Occidentalia Terrane *Pacific Rim Terrane *Pearya Terrane *Salinian Block *Slide Mountain Terrane *Smartville Block *Sonomia Terrane *Steel Mountain Terrane *Stikinia *Wrangellia Terrane *Yakutat Block *Yukon—Tanana Terrane South America *Arequipa-Antofalla *Chaitenia *Chilenia *Chiloé Block *Cuchilla Dionisio Terrane *Cuyania *Fitz Roy Terrane *Madre de Dios Terrane *Mejillonía *Nico Perez Terrane *Pampia *Paranapanema block *Piedra Alta Terrane *Tandilia Terrane

References




Citations




General bibliography

* McPhee, John (1981). ''Basin and Range''. New York: Farrar, Straus and Giroux. * McPhee, John (1983). ''In Suspect Terrain''. New York: Farrar, Straus and Giroux. * McPhee, John (1993). ''Assembling California''. New York: Farrar, Straus and Giroux.

External links


West Antarctica terrane analysis




{{Structural geology