scholarly journals Constraining of strain ellipsoid shape from sectional data in the Au bearing shear zone west of Iran

2019 ◽  
pp. 131-142 ◽  
Author(s):  
Mahdi Behyari
Keyword(s):  
Shear Zone ◽  
Strain Ellipsoid

Strain variation in shear belts

1970 ◽  
Vol 7 (3) ◽  
pp. 786-813 ◽  
Author(s):  
J. G. Ramsay ◽  
R. H. Graham
Keyword(s):  
Shear Zone ◽  
Strain State ◽  
Finite Strain ◽  
High Strain ◽  
Shear Zones ◽  
Finite Strains ◽  
Strain Variation ◽  
Strain Ellipsoid ◽  
Intensity Of Development ◽  
Variable Displacement

In rocks deformed by natural orogenic processes it is usual to find that the finite strain state varies from locality to locality. In some deformed rocks high strain states are localized within approximately planar zones commonly known as "shear belts".The general relationships that exist between variable displacement and variable strain state are established, and these general equations are solved for particular types of strain within shear zones. Only a limited number of types of solution are possible. Using these solutions the geometric forms of the structures found in shear zones in several regions are analyzed. Methods for computing the finite strain through these zones are described, and these finite strains are integrated to determine the total displacements across these zones. Schistosity is developed in some of the shear zones described. It is not parallel to the walls of the shear zone and is therefore not parallel to the dominant displacement (shear) directions. The schistosity appears to be formed perpendicular to the principal finite shortening (i.e. perpendicular to the shortest axis of the finite strain ellipsoid). Variations of the schistosity planes represent variations in the finite strain trajectories of XY planes in the strain states ([Formula: see text] ellipsoid axes). The intensity of development of the schistosity is correlated with the values of the principal finite strains.

scholarly journals Constrictional deformation of the Koster dyke swarm in a ductile sinistral shear zone, Koster islands, SW Sweden

1985 ◽  
Vol 34 ◽  
pp. 151-197
Author(s):  
Bjorn Hageskov
Keyword(s):  
Shear Deformation ◽  
Shear Zone ◽  
Simple Shear ◽  
Pure Shear ◽  
Dyke Swarm ◽  
Tectonic Event ◽  
Dyke Rock ◽  
Strain Ellipsoid ◽  
Shear Component ◽  
The Baltic

The Koster-Kattsund dyke swarm is an important element in the Sveconorwegian province of the Baltic shield. Dyke intrusion took place in the period 1225-1015 Ma. Throughout most of the swarm the dykes are strongly deformed and thoroughly recrystallised into lineated amphibolites as a result of a Sveconor- wegian tectonic event about 1000 Ma ago. However, in the Koster archipelago fresh dolerites can be fol­lowed northwards in to partially recrystallised metadolerites and finally into the totally recrystallised, line­ated amphibolites that characterise the swarm. In the Koster archipelago intense dyking resulted in the formation of a multilayered rock sandwich con­sisting of alternating layers of gneiss and dolerite. The sandwich trends NNE and dips 67°W. The dolerite dykes have a mean thickness of2.2 m and they occupy 15-20% of the total rock mass. To the northeast the sandwich becomes progressively deformed and ultimately shows very high strain of pure constrictional type. The deformation took place in a steep NW-SE-trending ductile shear zone. During the initial shear zone deformation (D4,) the sandwich underwent anticlockwise bending and the large Kyrkosund synform was formed. The fold plunges 303/66 and has a NW-SE-trending axial surface. The bending took place by means of flexural-slip folding in which the layer-parallel shearing was located in incompetent dyke layers. Increasing shearing and recrystallisation in a NW-SE-trending belt crossing the northern limb of the Kyr­kosund synform resulted in a softening of this belt. The succeeding event (D4b) was localised in this initial soft belt, and involved sinistral simple shear combined with pure shear resulting in horizontal widening and vertical shortening of the belt. This composite deformation formed the pure constrictional fabric now seen in the rocks. The strong D4b stretching was followed by the formation of trains of asymmetric folds (D 4c and d4a). It is demonstrated that volume changes in the dyke rock during deformation were negligible, and that no competence contrast between gneiss and dyke rock existed during the D 4b stretching. The finite con­strictional strain ellipsoid has the dimensions X = 7.07, Y = Z = 0.18. The composite simple/pure shear deformation that presumably caused the constriction has a simple shear component y = 10.9, correspond­ing to an angular shear of 84. 7°. The pure shear deformation resulted in a 3.4 times horizontal widening of the initial soft belt. The horizontal sinistral displacement within the shear zone was at least 35 km.

STRUCTURE OF THE CRUST ACROSS THE RED RIVER SHEAR ZONE IN NORTHERN VIETNAM FROM LINEAR ARRAY OBSERVATION

2019 ◽  
Author(s):  
Nguyen Van Duong ◽  
Huang Bor-Shouh ◽  
Huang Hsin-Hua ◽  
Nguyen Le Minh ◽  
Huang Win-Gee ◽  
...  
Keyword(s):  
Shear Zone ◽  
Linear Array ◽  
Red River ◽  
Northern Vietnam

A link between spatial distribution of the active tectonic dislocation and groundwater water resources in the Baikal-Stanovaya shear zone

2019 ◽  
Vol 5 ◽  
pp. 173-180 ◽  
Author(s):  
A.S. Ageev ◽  
◽  
R.K. Ilalova ◽  
A.M. Duryagina ◽  
I.V. Talovina ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Water Resources ◽  
Shear Zone ◽  
Active Tectonic ◽  
Tectonic Dislocation

CRUSTAL ARCHITECTURE AND TIMING OF AN ACCRETIONARY OROGEN: SALMON RIVER SUTURE ZONE AND WESTERN IDAHO SHEAR ZONE

2016 ◽  
Author(s):  
Sourav Krishna Nandi ◽  
◽  
Matthew P. McKay ◽  
Kevin L. Mickus
Keyword(s):  
Shear Zone ◽  
Suture Zone ◽  
Salmon River ◽  
Salmon River Suture Zone

THE SODA CREEK FISH CREEK SHEAR ZONE: USING MULTIPLE GEOCHRONOLOGIC METHODS TO UNRAVEL THE PROTEROZOIC STRUCTURAL HISTORY OF POLYPHASE DEFORMATION IN HIGHLY DEFORMED ROCKS

2016 ◽  
Author(s):  
Bart T. Cubrich ◽  
◽  
Kevin R. Chamberlain ◽  
Ernest Duebendorfer ◽  
Michael L. Williams ◽  
...  
Keyword(s):  
Shear Zone ◽  
Polyphase Deformation ◽  
Structural History ◽  
History Of
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