Gneiss

片麻岩

Gneiss is a metamorphic rock form characterized by banding caused by segregation of different types of rock, typically light and dark silicates. Rather than an indication of specific mineral composition, the term is an indication of texture. The "gneissic texture" refers to the segregation of light and dark minerals. It is indicative of high-grade metamorphism where the temperature is high enough, say 600-700 °C, so that enough ion migration occurs to segregate the minerals. Within the banded structure are mostly elongated and granular structures rather than sheets or plates. Some gneisses will split along the layers of materials, but most break in an irregular fashion.

片麻岩是一种变质岩，其特征是由不同类型的岩石分异作用形成的带状结构，通常由浅色和深色硅酸盐组成。该术语并不表示特定的矿物成分，而是表示岩石的结构。'片麻岩结构'指的是浅色和深色矿物的分异。这表明经历了高温高压的变质作用，温度高 enough，例如 600-700 °C，足以使离子迁移足够以分异矿物。在带状结构中，主要是长条状和粒状结构，而不是片状或板状。一些片麻岩会沿着材料层裂开，但大多数则以不规则方式破裂。

Gneiss often forms from the metamorphism of granite or diorite. The most common minerals in gneiss are quartz, potassium feldspar, and sodium feldspar. Smaller amounts of muscovite, biotite and hornblende are common. Gneiss can also form from gabbro or shale.

片麻岩通常由花岗岩或闪长岩的变质作用形成。片麻岩中最常见的矿物是石英、钾长石和钠长石。此外，云母、黑云母和角闪石的含量也较为常见。片麻岩也可以由辉长岩或页岩形成。

Metamorphic rock 变质岩	Texture 纹理	Parent rock 母岩	Description 描述
Gneiss 片麻岩	Foliated 层状的	Shale, granitic and volcanic rocks 页岩、花岗岩和火山岩	Coarse-grained, non-micaceous 粗粒度、非云母状

This example of gneiss is from Warm Springs, Georgia where a stressed formation produces it along with quartzite and schist, two other metamorphic rocks. The formation produces a large warm spring.

这种片麻岩来自佐治亚州温泉镇，该地区应力作用形成了这种岩石，同时还有石英岩和片麻岩两种变质岩。该地区形成了一个大型温泉。

Gneiss Examples

片麻岩例子

Index

Reference
Lutgens and Tarbuck
Ch 7

索引参考 Lutgens 和 Tarbuck 第7章

HyperPhysics*****Geophysics

HyperPhysics ***** 地球物理学

R Nave

Go Back