Terrane Explained
In geology, a terrane (;[1] [2] in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or "sutured" to crust lying on another plate. The crustal block or fragment preserves its distinctive geologic history, which is different from 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.
The older usage of terrane described a series of related rock formations or an area with a preponderance of a particular rock or rock group.
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 that 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 zones.
A tectonostratigraphic terrane is a fault-bounded package of rocks of at least regional extent characterized by a geologic history that differs from that of neighboring terranes. The essential characteristic of these terranes is that the present spatial relations are incompatible with the inferred geologic histories. Where terranes that lie next to each other possess strata of the same age, it must be demonstrable that the geologic evolutions are different and incompatible. There must be an absence of intermediate lithofacies that 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.[3]
Tectonostratigraphic terranes
Africa
Asia
Taiwan
- Coastal Range Terrane[5]
- Longitudinal Valley Terrane[5]
- Eastern Central Range Terrane[5]
- Western Central Range Terrane[5]
- Hsuehshan Range Terrane[5]
- Western Foothills Terrane[5]
- Coastal Plain Terrane[5]
Tibet
Australasia
Europe
- Alkapeca
- Armorican terrane
- Avalonia
- Avalon Composite Terrane
- Balearic 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[8]
Fennoscandia
North America
South America
References
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
Notes and References
- 2022-10-27.
- 2023-04-02.
- http://www.geop.ubc.ca/Lithoprobe/transect/terrane.html "Terranes"
- https://www.researchgate.net/figure/Schematic-map-of-the-Siberian-craton-showing-boundaries-of-the-craton-1-and-its_fig11_27202807 Schematic map of the Siberian craton showing boundaries of the craton and its terranes
- Terrane‐controlled crustal shear wave splitting in Taiwan . D. . Okaya . N.I. . Christensen . Z.E. . Ross. F.T. . Wu . Geophysical Research Letters . 2016 . 43 . 2 . 556–563 . 10.1002/2015GL066446. 2016GeoRL..43..556O . free .
- Aitchison, 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
- Mortimer. N. Rattenbury. MS. King. PR. Bland. KJ. Barrell. DJA. Bache. F. Begg. JG. Campbell. HJ. Cox. SC. Crampton. JS. Edbrooke. SW. Forsyth. PJ. Johnston. MR. Jongens. R. Lee. JM. Leonard. GS. Raine. JI. Skinner. DNB. Timm. C. Townsend. DB. Tulloch. AJ. Turnbull. IM. Turnbull. RE. High-level stratigraphic scheme for New Zealand rocks. New Zealand Journal of Geology and Geophysics. 57. 4. 2014. 402–419. 0028-8306. 10.1080/00288306.2014.946062. free.
- Pharao, et al. (1996) Tectonic map of Britain, Ireland & adjacent areas UK:British Geological Survey
- Bingen . B. . Henderson . I.H.C.. Viola . G. . Hendriks . B.W.H. . 2011 . The Grenvillian–Sveconorwegian orogeny in Fennoscandia: Back-thrusting and extensional shearing along the 'Mylonite Zone'. . 189 . 3–4 . 368–88 . 10.1016/j.precamres.2011.06.005 . 2011PreR..189..368V . 22 August 2015.
- Cuthberta . S.J. . Carswellb . D.A. . Krogh-Ravnac . E.J.. Waind . A. . 2000 . Eclogites and eclogites in the Western Gneiss Region, Norwegian Caledonides . . 52 . 1–4 . 165–195 . 10.1016/s0024-4937(99)00090-0. 2000Litho..52..165C .
- Book: Hild. Martha. Barr. Sandra. Geology of Nova Scotia. 2015. Boulder Publications. Portugal Cove. 9781927099438. 18.
- Book: Miller. Brent. Geology, Geochronology, and Tectonic Significance of the Blair River Inlier, Northern Cape Breton Island, Nova Scotia. 1997. Dalhousie University. Halifax. 260.
