| 释义 |
Definition of gneiss in English: gneissnoun nʌɪsnaɪs mass nounA metamorphic rock with a banded or foliated structure, typically coarse-grained and consisting mainly of feldspar, quartz, and mica. 片麻岩 Example sentencesExamples - The Borve Series is dominated by varieties of quartzo-feldspathic schist and gneiss, composed mainly of plagioclase, quartz, and biotite.
- Corundum occurs as an accessory mineral in some metamorphic rocks, such as mica schist, gneiss, and crystalline limestone.
- The sample is weakly banded amphibolite-facies gneiss consisting of quartz, plagioclase, biotite and hornblende.
- Between the Dharwas leucogranite and Kilar there is a simple planar structure of interspersed pelitic gneiss and leucogranite bands with a regional foliation dipping to the south or southeast.
- Quarzitic gneiss, low-grade metamorphic basic rocks, phyllites and dark chert can be abundant in some layers.
Derivativesadjective The Cenozoic melanges, widely distributed in central and eastern Sabah, exclusively contain mixed mafic-ultramafic, chert, and Cenozoic sandstone blocks, and lack any granitic, gneissic, or otherwise ‘continental’ clasts. Example sentencesExamples - This is a coarsegrained biotite gneiss with an average granodioritic composition, that is generally fairly homogeneous but locally shows gneissic banding, and is intruded by veins of microgranite and pegmatite.
- Scattered throughout the Pena Negra migmatites there are small bodies of Upper Proterozoic gneissic granodiorite and granite.
- The serpentinized harzburgite has a gneissic fabric shown by the orientation of the bastite pseudomorphs after orthopyroxene, typical of sub-ophiolitic upper mantle.
- The tonalite is gneissic, banded on a decimetre scale, and loaded with discrete mafic enclaves, metasedimentary xenoliths and garnet, feldspar and rutile xenocrysts, such that the body has a migmatitic appearance.
adjective The base of the Grampian Group beneath the oldest lithostratigraphical unit (Glen Shirra Subgroup) is nowhere exposed and its relationship to gneissose metasedimentary rocks that may constitute basement is unknown. Example sentencesExamples - The generally gneissose, NW-trending margin of the Mpuluzi batholith of the western domain shows a characteristic swing to more easterly trends at and close to the termination of the Welverdiend shear zone.
- For example, large pavements along the southern, gneissose margin of the Boesmanskop syenogranite are entirely made up of closely spaced S-C fabrics that are pervasively developed over several tens of metres.
- Post-Grenville deformation affecting the Armagh Gneiss Complex is heterogeneous but involves partial to complete recrystallization of the Grenville gneissose foliation.
- A large pebble with a gneissose appearance is a retrograded orthogneiss, consisting of quartz, plagioclase, feldspar and muscovite, with relics of biotite, mostly chloritized, and a weakly folded tectonic foliation.
adjective The granodiorite deposits at Aswan are often gneissoid in texture, exhibiting parallel orientated feldspar phenocrysts. Example sentencesExamples - This intrusion is not sharply defined everywhere and in many places the gneissoid foliation of the Yonkers granite blends so intimately with the gneiss of the Fordham formation that sharp, clear-cut contacts cannot be seen.
- There are also gray and fine grained red granites, and in some places they have taken a gneissoid form.
- In the inner sulfide zone gneissoid textures resulting from complete and vigorous replacement of the country rock have resulted.
- The youngest is yellowish-orange to yellowish-gray arkose, derived primarily from Precambrian gneissoid and granitoid rocks; it contains little clay, abundant calcium carbonates, and limonite cement, and is host for all uranium deposits of the district.
OriginMid 18th century: from German, from Old High German gneisto 'spark' (because of the rock's sheen). Rhymesadvice, bice, Brice, choc ice, concise, dice, entice, ice, imprecise, lice, mice, nice, precise, price, rice, sice, slice, speiss, spice, splice, suffice, syce, thrice, top-slice, trice, twice, underprice, vice, Zeiss Definition of gneiss in US English: gneissnounnīsnaɪs A metamorphic rock with a banded or foliated structure, typically coarse-grained and consisting mainly of feldspar, quartz, and mica. 片麻岩 Example sentencesExamples - The Borve Series is dominated by varieties of quartzo-feldspathic schist and gneiss, composed mainly of plagioclase, quartz, and biotite.
- Between the Dharwas leucogranite and Kilar there is a simple planar structure of interspersed pelitic gneiss and leucogranite bands with a regional foliation dipping to the south or southeast.
- Corundum occurs as an accessory mineral in some metamorphic rocks, such as mica schist, gneiss, and crystalline limestone.
- The sample is weakly banded amphibolite-facies gneiss consisting of quartz, plagioclase, biotite and hornblende.
- Quarzitic gneiss, low-grade metamorphic basic rocks, phyllites and dark chert can be abundant in some layers.
OriginMid 18th century: from German, from Old High German gneisto ‘spark’ (because of the rock's sheen). |