| 释义 |
tholeiite Petrogr.|ˈθəʊlɪaɪt|
Also 9 tholeite.
[ad. G. tholeiit (J. Steininger Geognostische Beschreibung des Landes zwischen der unteren Saar und dem Rheine: Nachträge (1841) 26), f. Tholei (now Tholey), name of a village in N.E. Saar, W. Germany: see -ite1.]
Formerly, a basaltic rock containing plagioclase feldspar, pyroxene, and glass, with little or no olivine, and having an intersertal texture; in recent use, any basaltic rock typically containing augite and a calcium-poor pyroxene (pigeonite or hypersthene), and distinguished from alkali basalts by a higher silica and lower alkali content.
1866P. H. Lawrence tr. von Cotta's Rocks Classified & Described ii. i. 138 Steininger has given the name of Tholeite to a rock found at the Schaumberg near Tholei, which he took for a compound of albite and titanite. But according to Bergemann's analysis this rock consists of 70 labradorite, 5 augite... It must therefore from its composition be considered a dolerite or basalt unless indeed it be considered as plutonic and classed with melaphyre. 1893[see intersertal a.]. 1922Q. Jrnl. Geol. Soc. LXXVIII. 229 The rocks were described as being..of one type: namely, olivine-free dolerites or tholeiites. 1924Thomas & Bailey in E. B. Bailey et al. Tertiary & Post-Tertiary Geol. Mull xxv. 280 Olivine-free and olivine-poor plagioclase-augite rocks with intersertal structure are classed by Rosenbusch as tholeiites. 1962Jrnl. Petrol. III. 352 The two planes identified in Fig. 1..divide the basalts into five unique groups..: 1. Tholeiite (oversaturated): normative quartz and hypersthene. 2. Tholeiite (saturated; hypersthene basalt): normative hypersthene. 3. Olivine tholeiite (undersaturated): normative hypersthene and olivine. 4. Olivine basalt: normative olivine. 5. Alkali basalt: normative olivine and nepheline. 1967Geol. Mag. CIV. 337 Significant use of the term tholeiite dates from 1887 when Rosenbusch redefined Steininger's Schaumberg, Saar tholeiite (1840) from Tholey as a melaphyre with intersertal texture... Bailey and Thomas (1924) in setting up their non-porphyritic central magma type of Mull recognized its ‘tholeiitic’ character using..Rosenbusch's definition of 1887... A more precise petrographic and chemical definition was to follow in Kennedy's important papers of 1931 and 1933 in which the non-porphyritic central magma type was redefined as the Tholeiitic Magma Type... Paramount in this definition was the recognition of the presence of an enstatite-augite or pigeonite series pyroxene in the ground-mass of tholeiitic lavas. 1978Nature 13 July 128/1 The two principal Icelandic basalt types are evolved tholeiites, mostly quartz-normative, with Mg/Mg + Fe2+ atomic ratio of 0·40 to 0·50, associated with fissure swarms and central volcanoes; and second, olivine tholeiites with Mg/Mg + Fe2+ in the o·60–0·70 range and predominantly associated with monogenetic shield volcanoes.
Hence tholeiˈitic a.
1922Q. Jrnl. Geol. Soc. LXXVIII. 237 The tholeiitic intrusions have produced little thermal alteration of the rocks into which they have been ultimately injected. 1933[see plateau basalt s.v. plateau 4]. 1933Amer. Jrnl. Sci. CCXXV. 247 The general thesis is..advanced that the olivine-basalt magma-type is the parent of the alkaline line of descent while the tholeiitic magma-type occupies a similar position with respect to the calc-alkaline rock suite. 1967[see tholeiite above]. 1970Nature 12 Dec. 1030/2 Geochemists have known for some time that [ocean] ridge basalts tend to be tholeiitic whereas alkali basalts are more likely to be found away from ridges. 1972F. H. Hatch et al. Petrol. Igneous Rocks (ed. 13) vii. 364 Alkali olivine-basalt magmas can differentiate towards alkali-enrichment; but tholeiitic magmas differentiate towards silica-enrichment. |