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单词 sial
释义 sial Geol.|ˈsaɪəl|
Also Sial.
[a. G. sial, f. si-licium silicon + al-uminium aluminium.
The name was altered from sal (see sal4 2) by G. Pfeffer in order to avoid confusion with other meanings of that word (see A. Wegener Die Entstehung der Kontinente und Ozeane (1920) iii. 22 and quot. 1924 below).]
The discontinuous upper layer of the earth's crust represented by the continental masses, which are composed of relatively light rocks rich in silica and alumina and may be regarded as floating on a lower crustal layer of sima; the material of which these masses are composed.
1922[see sal4 2].1923Rep. Brit. Assoc. Adv. Sci. 1922 364 Sial masses drift through the Sima like icebergs through the sea.1924J. G. A. Skerl tr. Wegener's Orig. Continents & Oceans iii. 36 Following a short communication from Pfeffer I should like to write ‘Sial’ instead of ‘Sal’ in order that there may be no confusion with the Latin word for Salt.1927Peake & Fleure Apes & Men ii. 18 Various crises have led to the splitting of the Sial, and..its fragments have wandered off in many directions.1950P. H. Kuenen Marine Geol. ii. 118 The isostatic equilibrium of the crust requires a considerable thickness of granitic sial in the continents and a rock of greater density in the oceanic sections.1954[see sal4 2].1978D. Bridgwater et al. in D. H. Tarling Evol. Earth's Crust ii. 63 In the type of Archaean craton displayed in southern Africa break up and partial destruction of earlier sial probably took place in a different tectonic regime.
Hence siˈalic a.1, of or pertaining to the continental crust or the material of which it is made.
1924J. G. A. Skerl tr. Wegener's Orig. Continents & Oceans iv. 59 Molten sialic masses (granite) from the under side of the South American block..have emerged on its posterior edge.1944A. Holmes Princ. Physical Geol. ii. 14 There should be bulges..where gravity is relatively low; that is to say, wherever the outer part of the crust is composed of light sialic rocks. Such places are the continents.1955Sci. Amer. Sept. 62/1 Because granite is the chief sialic rock and basalt the chief simatic one, the continents are most commonly described as granitic and the ocean basins as basaltic.1970Ibid. Feb. 32/3 Stresses in the earth's crust may crack the sialic layer, producing faults and fissures that can be as much as 20 meters wide.1975Nature 3 Apr. 397/2 Localised partial melting of ancient, sialic crust may..occur in the zone of heating above large bodies of basic igneous magma introduced into high crustal levels.
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