Veins in tension cracks

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These photos are limited to veins filling tension cracks.

91_115. Conjugate en echelon tension gashes in Old Red Sandstone.  Marloes sands, St. Bride's, Dyfed, Wales. [SM777077; 51.72347,-5.218359]
Each zone gives the local strain in the small shear zones. The white quartz veins are perpendicular to the long strain axis. The narrow dark zones perpendicular to the veins are pressure solution cleavage, and are perpendicular to the local axis of maximum shortening. The shear sense on the horizontal zone is left lateral, and the shear zone that slopes down to the left is right lateral. This is consistent with a bulk strain in which the maximum shortening bisects the acute angle between the shear zones.


85_405. Fold hinge with tension gashes.  Hele Bay, Ilfracombe, Devon, England. [SS532475; 51.212707,-4.093795]
The tension gashes indicate extension parallel to the fold hinge.


85_425. Encephalon tension gashes in a shear zone.  Hartland Quay, Devon, England.  [SS225250; 50.995643,-4.531395]
The cracks indicate a shear of the top to the right. The orientation of the veins is perpendicular to the long axis of the strain ellipse.


85_439. Folded tension gashes.  Welcome, north of Bude, Devon, England. [SS212181; 50.934558, -4.546003]


85_441. Tension gashes offset on one limb of fold. Welcome, north of Bude, Devon, England. [SS212181; 50.934558, -4.546003]

Millook Haven, south of Bude, Devon, England. Grid Ref. SS185 005


85_511. Tension gashes on overturned limb. Millook Haven, Cornwall. [SS183003; 50.772364,-4.577193]


85_512. Core zone of recumbent fold with tension gashes in the lower limb. Millook Haven, Cornwall. [SS183003; 50.772364,-4.577193]


85_513. En echelon tension gashes defining a series of parallel shear zones. Millook Haven, Cornwall. [SS183003; 50.772364,-4.577193]


85_514. Tension gashes in a progressive shear. Millook Haven, Cornwall. [SS183003; 50.772364,-4.577193]


85_515. Tension gashes rotated during a progressive shear. Millook Haven, Cornwall. [SS183003; 50.772364,-4.577193]


85_516. Tension gashes in conjugate shears. Millook Haven, Cornwall. [SS183003; 50.772364,-4.577193]


85_517. Tension gashes rotated during a progressive shear.  Millook Haven, Cornwall. [SS183003; 50.772364,-4.577193]


Extension "Pressure" shadows


88_009. Quartz "pressure" shadows on garnets, representing extension parallel to foliation in amphibolite.
Mahood Creek, Harrison Lake, BC. [49.362544,-121.59605]

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