Relationships between faults, extension fractures and veins, and stress

Blenkinsop, T.G. (2008) Relationships between faults, extension fractures and veins, and stress. Journal of Structural Geology, 30 (5). pp. 622-632.

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Faults are commonly related to extension fractures, defined here as including extension veins. Extension fracturing is integral to fault initiation and propagation, and extension fractures also form after fault slip. In these situations, fault planes contain the intermediate principal stress σ2, and slip is perpendicular to the line of intersection between the fault and the extension fractures. However, for reactivated faults, multiple fault sets, and faults formed according to the Healy theory, σ2 is not necessarily within the fault plane. A theoretical analysis shows that the trace of an extension fracture on a fault can make angles from 0° to 90° with the maximum resolved shear stress. The angle depends on the fault orientation relative to the principal stresses, and the ratio between the stresses. Extension fractures only intersect faults perpendicular to the maximum resolved shear stress on faults containing the maximum or intermediate principal stresses, or when their magnitudes are equal (σ1 = σ2). Field observations show that extension fractures can intersect faults along lines at oblique angles to slip directions, as predicted by the theory. Such angles may be indicators of fault reactivation, multiple sets of faults, or Healy theory faulting.

Item ID: 6688
Item Type: Article (Research - C1)
ISSN: 1873-1201
Keywords: fault; slip; extension fracture; vein; stress; dynamic analysis
Date Deposited: 30 Mar 2010 03:49
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040312 Structural Geology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 80%
84 MINERAL RESOURCES (excl. Energy Resources) > 8499 Other Mineral Resources (excl. Energy Resources) > 849999 Mineral Resources (excl. Energy Resources) not elsewhere classified @ 10%
84 MINERAL RESOURCES (excl. Energy Resources) > 8401 Mineral Exploration > 840105 Precious (Noble) Metal Ore Exploration @ 10%
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