Geology 3120 Rock Fabric Objectives Attitudes of Fabric

Geology 3120 - Rock Fabric

Objectives • Attitudes of Fabric • Cleavage • Lineations • Foliations

Fabrics

Cleavage • General definition - closely-spaced, aligned, planar to curviplanar penetrative surfaces • Continuous verses disjunctive cleavage - planar verses non -planar • Mechanical realignment and growth of clay minerals • Pressure dissolution process

Slaty Cleavage n Mechanical alignment and growth of clay minerals

Slaty Cleavage n Where is the bedding?

Slaty Cleavage n Where is the cleavage?

Slaty Cleavage n. What direction is the nearest anticline?

Pressure Dissolution Cleavage n Extensional veins shortened in silt

Axial Planar Cleavage n Identify the folds

Axial Planar Cleavage n Identify the cleavage

Axial Planar Cleavage n Identify the axial surfaces

Axial Planar Cleavage

Bedding Axial Planar Cleavage Axial Surfaces

Cleavage Vergence West Central East

Cleavage Vergence Central West East

Pressure Solution Cleavage - Limestone n Insoluble material is typically contained in the stylolite

Introduction to Lineations § One-Dimensional Features § Slickenlineations § Fault grooves § Stretched conglomerates § Boudins

Slickenline Lineations n Calcite mineral growth on a fault plane

Grooves n Grooves are parallel to strike n What type of fault is this?

Stretched Conglomerates Rock has a foliation, lineation depends on whether clasts are disc- or rod-shaped

Boudins

Introduction to Foliations § Bring in the next dimension § Deformation or organization of grains with respect to a two-dimensional surface § Foliations in addition to lineations may yield information about the stretching direction

Foliations with Lineations

References Slides 3 - 6: http: //earth. leeds. ac. uk/minor/ductile/describing/lin-plane. htm Slide 1, 8 - 11: http: //earth. leeds. ac. uk/minor/cleavage/slatey. htm Slide 12: http: //earth. leeds. ac. uk/minor/dmt/psolncleav. htm Slides 13 - 16: http: //earth. leeds. ac. uk/folds/describing/cleavage. htm Slide 17 - 20: http: //earth. leeds. ac. uk/folds/describing/cleavage/cleaverge. htm Slide 21: http: //earth. leeds. ac. uk/minor/dmt/stilolite. htm Slide 23: http: //earth. leeds. ac. uk/minor/faults/strifibres. htm Slide 24: http: //earth. leeds. ac. uk/minor/faults/grooves. htm Slide 25: http: //earth. leeds. ac. uk/minor/ductile/vasgo/congs. htm Slide 26: http: //earth. leeds. ac. uk/minor/extend/boudyke. htm Slide 26: http: //earth. leeds. ac. uk/strain/gallery/boudin. html Slide 28: http: //earth. leeds. ac. uk/minor/ductile/vasgo/myllin. htm Slide 29: http: //earth. leeds. ac. uk/minor/ductile/gallery/plattgen. htm