Fractures

Faults Joints

Joint sets

Group of joints parallel jointsHave common origin

Recognizing joints

Lack of offsetJoint surface

textures Hackle Origin Plumose Rib Marks Fringe Joints Rib

mark

Characterization of Single Joints

Surface texturesMineralizationShapeOrientationLengthAperturePath or trace

pattern

Courtesy of Zion National Park

Recognizing Joint Sets

Single joint set parallel and evenly spaced

Multiple sets form a system

Abutting relationships

Which set is youngest?

Characterization of Joint Sets

OrientationTypical joint

lengthDensity/spacingRelation among

setsLateral extent Individual joint

interactionsJoints at Arches National Park

Polygonal Joints

Cooling basalts and drying mud

‘Y’ intersections

Veins, sills and dikes

Also features with opening separation

Anti-opening cracks?

StylolitesCompaction Bands

Petit et al, JSG

Mapping Fractures

Map and analysis by Ze’ev Reches

Map relation of fractures to other structures

Joints Folds Faults Stratigraphy

Faults Folds Stratigraphy

Myers and Aydin, 2004, JSG

Gross, 1995, GSA Bull

Fractured Rock MassMoenave Fm. in Utah

3D Conceptualization

fracture

fracturetermination

Outcrop Conceptualization