geosyncline

/jee'oh sin"kluyn/, n. Geol.
a portion of the earth's crust subjected to downward warping during a large span of geologic time; a geosynclinal fold.
[1890-95; GEO- + SYNCLINE]

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I
Linear trough of subsidence of the Earth's crust, in which vast amounts of sediment accumulate.

The filling of a geosyncline with thousands or tens of thousands of feet of sediment is accompanied by folding, crumpling, and faulting of the deposits. Intrusion of crystalline igneous rock and regional uplift complete the transformation into a belt of folded mountains. The concept was introduced by James Hall in 1859 and is basic to the theory of mountain building. See also Andean Geosyncline; Appalachian Geosyncline; Cordilleran Geosyncline.
II
(as used in expressions)

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      linear trough of subsidence of the Earth's crust within which vast amounts of sediment accumulate. The filling of a geosyncline with thousands or tens of thousands of feet of sediment is accompanied in the late stages of deposition by folding, crumpling, and faulting of the deposits. Intrusion of crystalline igneous rock and regional uplift along the axis of the trough generally complete the history of a particular geosyncline, which is thus transformed to a belt of folded mountains. The concept of the geosyncline was introduced by the American geologist James Hall (Hall, James) in 1859 and is basic to the concept of mountain building.

      Two segments of a geosyncline are recognizable in the rock strata of many of the world's mountain systems today. Thick volcanic sequences, together with graywackes (sandstones rich in rock fragments with a muddy matrix), cherts, and various sediments reflecting deepwater deposition or processes, were deposited in eugeosynclines, the outer, deepwater segment of geosynclines. The occurrence of limestones and well-sorted quartzose sandstones, on the other hand, is considered to be evidence of shallow-water formation, and such rocks form in the inner segment of a geosyncline, termed a miogeosyncline.

      Aside from the parts or segments of a geosyncline, several types of mobile zones have been recognized and named. Among the more common of these are the taphrogeosyncline, a depressed block of the Earth's crust that is bounded by one or more high-angle faults and that serves as a site of sediment accumulation, and the paraliageosyncline, a deep geosyncline that passes into coastal plains along continental margins.

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Universalium. 2010.

Look at other dictionaries:

  • geosyncline — 1895, back formation from geosynclinal (1873); see GEO (Cf. geo ) + SYNCLINAL (Cf. synclinal) …   Etymology dictionary

  • geosyncline — [jē΄ōsin′klīn΄] n. [ GEO + SYNCLINE] a very large, troughlike depression in the earth s surface containing masses of sedimentary and volcanic rocks …   English World dictionary

  • Geosyncline — In geology, geosyncline is a term still occasionally used for a subsiding linear trough that was caused by the accumulation of sedimentary rock strata deposited in a basin and subsequently compressed, deformed, and uplifted into a mountain range …   Wikipedia

  • geosyncline — noun Date: 1895 a great downward flexure of the earth s crust • geosynclinal adjective …   New Collegiate Dictionary

  • geosyncline — noun A large, linear depression in the Earths crust in which sediment accumulates …   Wiktionary

  • geosyncline — n. downward curve of the Earth s surface (Geology) …   English contemporary dictionary

  • geosyncline — geo·syncline …   English syllables

  • geosyncline — ge•o•syn•cline [[t]ˌdʒi oʊˈsɪn klaɪn[/t]] n. gel a portion of the earth s crust subjected to downward warping during a large span of geologic time • Etymology: 1890–95 ge o•syn•cli′nal, adj …   From formal English to slang

  • geosyncline — /dʒioʊˈsɪnklaɪn/ (say jeeoh sinkluyn) noun a portion of the earth s crust subsiding for a long time, prevalently linear and usually containing great thicknesses of sedimentary and volcanic rocks …   Australian English dictionary

  • geosyncline — …   Useful english dictionary

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