Slickensides are striations on rock, created by the friction between rocks when they slide past each other along a fault plane. The slickensides shown here are probably not part of a major fault, but they may be part of small regions within a larger fault zone where rocks under stress slide against each other.
What are slickenlines?
Slickenlines are lineations commonly found within shear fractures and fault surfaces that are thought to record slip motion and mechanical wear occurring during faulting.
How is Slickenside created?
Slickensides are smooth, often polished surfaces of parallel scratches or grooves. They form at fault planes when rocks on either side scrape past each other. This can happen when rock is sheared suddenly during an earthquake or gradually during fault creep. Any kind of rock can show slickensides.
How are slickensides used to determine the slip orientation of the fault plane?
When rocks break under compressional stress, the hanging wall moves up relative to the footwall, and a reverse fault forms (Figure 3). The scratches on the fault plane surface are called slickensides. Slickensides may record the slip orientation of the fault plane, and may even feel smoother in the direction of slip.
What is mineral lineation?
Mineral lineations may be parallel or inclined to the axes of related folds. They indicate a stretching direction if the involved minerals are segmented along the lineation. They also can define the intersection between foliation planes and rotation axes of rotating minerals.
How are Boudins formed?
Boudinage is a geological term for structures formed by extension, where a rigid tabular body such as hornfels, is stretched and deformed amidst less competent surroundings. The competent bed begins to break up, forming sausage-shaped boudins.
What is lineation in structural geology?
Lineation is a general term to describe any repeated, commonly penetrative and parallel alignment. of linear elements within a rock (to envision lineation, imagine packages of spaghetti). A lineation. may be a primary igneous or sedimentary fabric element, such as an array of elongate K-feldspar.
Are Slickensides a type of Lineation?
1. A lineation on a fault or bedding plane caused by the frictional movement of one rock body against another.
What is meant by lineation?
Definition of lineation 1a : the action of marking with lines : delineation. b : outline. 2 : an arrangement of lines.
What is lineation in geography?
A lineation is any linear feature or element in a rock , and can occur as the product of tectonic, mineralogical, sedimentary, or geomorphic processes. Lineations are the one-dimensional counterparts of foliations, and both are part of the fabric (geometric organization of features) of a rock.
What is Boudinage in rocks?
boudinage, (from French boudin, “sausage”), cylinderlike structures making up a layer of deformed rock. Seen in cross section, the cylinders, or boudins, are generally barrel-shaped but may be lenslike or rectangular.
What is Lineation in structural geology?
What are slickensides or slickenlines?
Slickensides or slickenlines (slicken = glossy) are striated mineral growth or mechanical abrasions on the surface of faults and in fact, any surface that accommodates shear displacement. Thus, while not an essential component of a fault, they are included here because of their connection with faults.
What causes slickensides on a fault?
This surface is often characterized by slickensides that result from the growth of mineral fibres ( Fig. 2.17 ). Slickensides or slickenlines (slicken = glossy) are striated mineral growth or mechanical abrasions on the surface of faults and in fact, any surface that accommodates shear displacement.
Where are slickensides found in North America?
Slickenside. Slickensides are common in Coastal Plain soils and also in the deeper upland soils at the base of hills or solution cavities (INEGI 1998a, Beach 1998). From: Rivers of North America, 2005. Related terms: Fault Plane; Mudstone; Shear Zone; Vertisols; Reflectance; Nodule; Sandstone; Deformation; Zircon
