flasern.
/ˈflɑːzə/ Geology.
Used attributively to denote the presence of lenses of little-altered rock in a streaky parent rock that has been metamorphosed by shearing under pressure; it is found mainly in gabbro, gneiss, and granite; so flaser-gabbro, flaser-granite, flaser-rock, flaser-schist, flaser-structure.
ΘΚΠ
the world > the earth > structure of the earth > structural features > discontinuity or unconformity > [adjective] > intrusive > lens
flaser1888
1888 C. Lapworth Page's Geol. (ed. 12) 108 A curious veiny or banded structure (flaser structure).
1888 J. J. H. Teall Brit. Petrogr. vii. 177 In speaking of the foliated gabbros it is convenient to recognise two principal types which may be designated by the terms flaser-gabbro and gabbro-schist.
1888 J. J. H. Teall Brit. Petrogr. vii. 245 In some of these a flaser structure has been developed by interstitial movement.
1891 G. A. J. Cole Aids Pract. Geol. 210 This structure..appears to arise by interaction of the minerals when subjected to earth-pressures (‘Flaser-gabbros’, etc.).
1930 B. N. Peach & J. Horne Chapters Geol. Scotl. 58 Flaser structure with abundant phacoids of felspar and hornblende.
1951 F. J. Turner & J. Verhoogen Igneous & Metamorphic Petrol. xxi. 543 There is continuous transition from mylonites to a group of rocks variously referred to as augen schists, mylonite gneisses, flaser rocks, and blastomylonites.
1954 H. Williams et al. Petrogr. XI. 204 The terms flaser gabbro and flaser granite have long been applied by European petrologists to cataclasites in which granulated streaks and laminae swirl around and between streamlined eyes of undestroyed gabbro or granite.
This entry has not yet been fully updated (first published 1933; most recently modified version published online September 2018).
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n.1888