| 释义 |
oligomictic, a.|ɒlɪgəʊˈmɪktɪk|
[f. oligo- + Gr. µικτ-ός mixed + -ic.]
1. Petrol. [ad. Russ. oligomiktovȳĭ (M. S. Shvetsov Petrografiya Osadochnȳkh Porod (1934) viii. 155).] (See quot. 1935.)
1935Jrnl. Sedimentary Petrology V. 106/2 Rocks consisting of one to two dominant minerals are termed oligomictic and those composed of several minerals polymictic... The book is written in Russian... The review is based on a typewritten summary in English. 1949F. J. Pettijohn Sedimentary Rocks xiv. 438 Schwetzoff..noted that oligomictic rocks are the characteristic deposits of epicontinental seas and are found rarely in geosynclinal depressions, whereas polymictic rocks are characteristic of geosynclinal regions. 1959W. W. Moorhouse Study of Rocks in Thin Section xix. 337 The typical oligomictic conglomerate is composed predominantly of quartz. 1971Nature 28 May 247/1 Structureless to planar cross-stratified, sheet-like bodies of oligomictic conglomerates and subarkoses are interbedded.
2. Limnology. Applied to a lake that exhibits a stable thermal stratification and only rarely undergoes an overturn.
1956Hutchinson & Löffler in Proc. Nat. Acad. Sci. XLII. 84 Although at low altitudes in the humid tropics small temperature gradients can maintain stable stratifications, no stable stratification develops at the low temperatures of high altitudes, where the density difference per degree centigrade is very small. The lack of seasonal variation, that permits almost perennial stratification at low altitudes in equatorial latitudes, thus permits perennial circulation at high altitudes in the same latitudes. We propose for these two types of equatorial lake the terms oligomictic and polymictic, respectively. 1968R. W. Fairbridge Encycl. Geomorphol. 617/1 The lake water body is stratified, thus oligomictic. |