pressure shadow

pressure shadow

[′presh·ər ‚shad·ō]
(petrology)
In structural petrology, an area adjoining a porphyroblast, characterized by a growth fabric rather than a deformation fabric, as seen in a section perpendicular to the b axis of the fabric. Also known as pressure fringe; strain shadow.
References in periodicals archive ?
This site represents a highly prospective zone for mineralisation where the anastomosing structure splays from the granite intrusive creating a structural pressure shadow area in ductile sedimentary units.
PRESSURE Shadow Health Secretary Andy Burnham said: "When hospitals are under so much pressure, it makes no sense to close walk-in centres.
The gold particles transported by the ancient river system are typically deposited in pressure shadows behind and below large cobbles and boulders.
Mica and ilmenite parallel to the regional foliation wrap around garnet, whereas quartz and scarce mica flakes occur in strain pressure shadows. The small scale folding of the schistosity plane produced crenulation cleavage, accompanied by segregation of quartz into horizontal layers.
Textural sector zoned garnet growth during [D.sub.1] ([S.sub.1]), developing strain pressure shadows and shearing away cleavage domes
Textural sector zoned garnet growth during [D.sub.1] ([S.sub.1]), with quartz inclusions derived from strain pressure shadows
The step 2 was characterized by a textural sector-zoned garnet growth during [D.sub.1] ([S.sub.1]), developing strain pressure shadows and shearing away cleavage domes.
(a) Pseudo-hexagonal textural sector- and sigmoidal-zoned garnet associated to staurolite, which are wrapped by the main foliation ([S.sub.2]) of the rock developed by muscovite and biotite domains, developing strain pressure shadows; (b) small garnet partially included in staurolite porphyroblast, which displays a sigmoidal pattern of inclusions of quartz and ilmenite ([S.sub.1]) discordant with [S.sub.2]; (c) irregular garnet porphyroblasts, which display tectonic dissolution and are cross cut by quartz veinlets; (d) garnet porphyroblasts showing strong tectonic dissolution and staurolite porphyroblasts with a sigmoidal [S.sub.1] discordant with [S.sub.2].