Pressure shadow
Jump to navigation
Jump to search
A pressure shadow (also called strain shadow) is a term used in metamorphic geology to describe a microstructure in deformed rocks that occurs adjacent to a relatively large, undeformed particle, such as a porphyroclast. Pressure shadows often appear in thin sections as pairs of roughly triangular regions that are elongated parallel to the foliation around a clast of a different mineral.[1] Pressure shadows that contain fibrous mineral textures are also termed pressure fringes or strain fringes.[2]
Formation
[edit | edit source]During deformation, minerals can migrate by plastic flow or may grow by diffusive mass transport into the lower-stress regions created by a rigid porphyroclast or porphyroblast.[3]
References
[edit | edit source]- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
