单词 | ptygmatic |
释义 | ptygmaticadj. Geology. Designating a highly sinuous folding, for example of granitic layers and veins in certain gneisses and migmatites; (also) displaying such folding.Originally used by Sederholm in a somewhat broader sense. ΘΚΠ the world > the earth > structure of the earth > structural features > fold or dip > [adjective] > others plagioclinal1879 isoclinal1882 downdip1904 ptygmatic1907 up-dip1916 1907 J. J. Sederholm in Bull. de la Comm. Géol. de la Finlande xxiii. 110 [English summary of original Swedish article] The primary folding caused by melting, he designates as ptygmatic... These suggestions are made with every reservation. 1926 G. W. Tyrrell Princ. Petrol. xxi. 333 (caption) Ptygmatic folding of a quartz vein in amphibolite. 1952 Geol. Mag. 89 1 The term ‘ptygmatic’ was originally coined by Sederholm in 1907..to describe ‘the primary folding caused by melting’ in gneisses and migmatites. The word.., as defined, would embrace most of the contortions, many of which are now included in the term ‘flow fold’, commonly seen in migmatite zones the world over... The term was later restricted by Sederholm (1926) to those tortuous quartzo-felspathic veins, which occur in areas of granitization. 1970 K. C. Jackson Textbk. Lithol. vii. 420 (caption) Ptygmatic folding of a pegmatite dike in gneiss. 1993 Jrnl. Petrol. 34 37 Some veins are also folded or ptygmatic. Derivatives ptygˈmatically adv. so as to give ptygmatic folds. ΘΚΠ the world > the earth > structure of the earth > structural features > fold or dip > [adverb] > others synclinally1855 downdip1923 ptygmatically1928 isoclinally1936 up-dip1957 1928 Summary of Progress Geol. Surv. Great Brit. 1927 ii. 72 Other observers of what are certainly ptygmatically folded veins have not accepted Sederholm's explanation. 2001 Jrnl. Geodynamics 32 574 Locally layers of calcite are boudinaged or ptygmatically folded as a multilayer. This entry has been updated (OED Third Edition, September 2007; most recently modified version published online March 2022). < adj.1907 |
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