6.3: Metamorphic Textures - Geosciences LibreTexts
Gneissic banding is a metamorphic foliation in which visible silicate minerals separate into dark and light bands or lineations. These grains tend to be coarse and often folded. A rock with this texture is called gneiss. Since gneisses form at the highest temperatures and pressures, some partial melting may occur.
Flow banding - Wikipedia
Flow banding is caused by friction of the viscous magma that is in contact with a solid rock interface, usually the wall rock to an intrusive chamber or, if the magma is erupted, the surface of the Earth across which the lava is flowing.
Banding in igneous rocks - SpringerLink
Rocks with the type of inhomogeneity known as structural banding display variations in structure and texture that are not accompanied by appreciable variations in mineralogy and chemistry. Such banding is well developed in many glassy or fine-grained siliceous rocks that tend to occur in shallow intrusions or as extrusions (e.g., rhyolites ...
banding – An Introduction to Geology
A separation of light (felsic) and dark (mafic) minerals in higher grade metamorphic rocks like gneiss. Associate Professor, Salt Lake Community College, Salt Lake City, Utah View all posts by Chris. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Metamorphic Textures - Tulane University
These dark colored minerals tend to become segregated into distinct bands through the rock (this process is called metamorphic differentiation), giving the rock a gneissic banding. Because the dark colored minerals tend to form elongated crystals, rather than sheet- like crystals, they still have a preferred orientation with their long ...
Textural banding, consisting of well-defined alternating thin layers of coarse- and fine- grained rocks, is described for gabbros and metagabbros of the Josephine peridotite-gabbro complex of the Klamath Mountains of southwestern Oregon.
What causes compositional banding in metamorphic rocks?
2022年12月8日 · In the first stage of metamorphism, the rock undergoes compression, which causes the crystals of both minerals to align along their narrowest axis. In a second stage, the rock then undergoes shearing, which further elongates the crystals, leading to gneissic bands.
by compositional banding • Commonly, light and dark bands of felsic and mafic mineralogy alternate. • The light-colored layers are rich in feldspar and quartz, whereas darker layers contain more mafic minerals amphibole/pyroxene and/or biotite. • Color banding in gneiss is called gneissosity. Inheritance from an original lithology ...
Banding - Vocab, Definition, and Must Know Facts | Fiveable
Banding serves as an important indicator for interpreting the metamorphic history of a geological region. By analyzing the patterns, thicknesses, and compositions of bands, geologists can infer details about past tectonic activity, thermal events, and …
UNDERSTANDING TEXTURES AND FABRICS 1 - Wiley Online Library
This chapter discusses banding types and scales, and considers the common types of planar features and lineations found in metamorphic rocks. The chapter introduces the terminology and defines some of the implications of this terminology for the resulting textures and fabrics.