- Foliations are planar fabrics in rocks that form sheets or layers. They include bedding, cleavage, schistosity, and gneissosity.
- Lineations are linear structural features in rocks that result from the parallel alignment of elongate minerals, fossils, or other linear features. They include stretched pebbles, intersection lineations, and slickensides.
- Foliations and lineations can be primary (formed during rock formation) or secondary (formed by deformation after rock formation). Secondary fabrics provide important clues about a rock's deformation history.
A shear zone is a zone of strong deformation (with a high strain rate) surrounded by rocks with a lower state of finite strain.
It is characterized by a length to width ratio of more than 5:1.
In the Upper crust, where rock is brittle, the shear zone takes the form of a fracture called a fault.
In the lower crust and mantle, the extreme conditions of pressure and temperature make the rock ductile. That is, the rock is capable of slowly deforming without fracture.
The current ppt discusses the different types of lineations formed due to deformation.
Lineations are genetically related to the foliation planes on which they occur, particularly where both are shaped by mineral orientations. Therefore, the planar and linear fabrics are both together aspects of the same three-dimensional geometry, which is related to the shape of the finite strain ellipsoid or,
more important still, to the history of incremental strains.
A shear zone is a zone of strong deformation (with a high strain rate) surrounded by rocks with a lower state of finite strain.
It is characterized by a length to width ratio of more than 5:1.
In the Upper crust, where rock is brittle, the shear zone takes the form of a fracture called a fault.
In the lower crust and mantle, the extreme conditions of pressure and temperature make the rock ductile. That is, the rock is capable of slowly deforming without fracture.
The current ppt discusses the different types of lineations formed due to deformation.
Lineations are genetically related to the foliation planes on which they occur, particularly where both are shaped by mineral orientations. Therefore, the planar and linear fabrics are both together aspects of the same three-dimensional geometry, which is related to the shape of the finite strain ellipsoid or,
more important still, to the history of incremental strains.
Komattite
Named after the Komati River in South Africa.
first described by Morris and Richard (twins) for ultramafic units in the Barberton Greenstone belt of South Africa.
Mostly of komatiite are Archean age
distributed in the Archaean shield areas.
Also a few are Proterozoic and Phanerozoic.
In all ages komatiites are highly magnesium.
Mostly a volcanic rock; occasionally intrusive.
Mafic rocks were identified as extrusive because of their volcanic textures and structures, and they seem to have been accepted as a normal component of Archean volcanic successions, Abitibi in Canada.
The ultramafic rocks were interpreted as intrusive which are founded as sills and dykes, Barberton in South Africa.
Spinifex texture-typical of Komatiites:
Boundary problems between :-
Precambrian/Cambrian
Permian/Triassic
Cretaceous/Tertiary
Neogene/Quaternary
Stratigraphic boundaries are determined by one or more of geological events such as volcanic activity, sedimentation, tectonism, paleo-environments & evolution of life.
Faunal records have played major role in determining the boundaries of the Phanerozoic units.
The other geological events are dated on the evidence of fossil records.
Komattite
Named after the Komati River in South Africa.
first described by Morris and Richard (twins) for ultramafic units in the Barberton Greenstone belt of South Africa.
Mostly of komatiite are Archean age
distributed in the Archaean shield areas.
Also a few are Proterozoic and Phanerozoic.
In all ages komatiites are highly magnesium.
Mostly a volcanic rock; occasionally intrusive.
Mafic rocks were identified as extrusive because of their volcanic textures and structures, and they seem to have been accepted as a normal component of Archean volcanic successions, Abitibi in Canada.
The ultramafic rocks were interpreted as intrusive which are founded as sills and dykes, Barberton in South Africa.
Spinifex texture-typical of Komatiites:
Boundary problems between :-
Precambrian/Cambrian
Permian/Triassic
Cretaceous/Tertiary
Neogene/Quaternary
Stratigraphic boundaries are determined by one or more of geological events such as volcanic activity, sedimentation, tectonism, paleo-environments & evolution of life.
Faunal records have played major role in determining the boundaries of the Phanerozoic units.
The other geological events are dated on the evidence of fossil records.
Fabric of a rock is the geometric arrangement of component features in the rock, seen on a scale large enough to include many samples of each feature.
The features themselves are called fabric elements. Examples of fabric elements include mineral grains, clasts, compositional layers, fold hinges, and planes of parting.
Fabrics that form as a consequence of tectonic deformation of rock are called tectonic fabrics, and fabrics that form during the formation of the rock are called primary fabrics.
Grade 8 Integrated Science Chapter 12 Lesson 1 on relative-age dating of fossils and rock layers. This lesson explains how scientists use rock layers to determine a age of a rock or fossil compared to others. The goal of this lesson is for students to be able to correctly order rock layers by age and to know the different disconformities and nonconformities.
HOW THE JOINTS WERE FORMED ,WHAT ARE THE FORMATION OF JOINTS ,CLASSIFICATION OF JOINTS ,ORIGIN AND OCCURENCE OF JOINTS ,AND ENGINEERING IMPORTANTS OF JOINTS HAS BEEN GIVEN HERE .FOR ANY CLARIFICATION PLEASE CONTACT VIA EMAIL .
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An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Biological screening of herbal drugs: Introduction and Need for
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Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
2. Fabric
The fabric of a rock is the geometric arrangement of component features in
the rock.
If there is no preferred orientation (i.e., alignment) of the fabric elements,
then we say that the rock has a random fabric. Undeformed sandstone,
granite, or basalt are rocks with random fabrics.
Deformed rocks typically have a non-random fabric or a preferred fabric, in
which the fabric elements are aligned in some manner and/or are repeated
at an approximately regular spacing.
3. There are two main classes of preferred fabrics in rock.
A planar fabric, or foliation, is one in which the fabric element is a planar
or tabular feature.
A linear fabric, or lineation, is one in which the fabric element is
effectively a linear feature.
Foliations and lineations can be subdivided into primary (pre-
deformational) ones, such as bedding, and secondary (deformational)
ones.
If the fabric elements are closer than 1 mm (that is, below the resolution of
the eye), the fabric is continuous. When there is an obvious spacing between
fabric elements, we say that the fabric is spaced.
4.
5. Fabrics that form as a consequence of tectonic deformation of rock are
called tectonic fabrics, and fabrics that form during the formation of the
rock are called primary fabrics.
Rocks with a penetrative tectonic fabric are also called tectonites.
When linear fabric elements dominate, the rock is called an L-tectonite,
A rock with dominantly planar fabrics is called an S-tectonite.
The rocks with both types of fabric elements are called LS-tectonites.
6. Foliation
A foliation is any type of planar fabric in a rock, property of rocks whereby
break along approximately parallel surfaces.
Sedimentary rocks shows a property called bedding fissility in which rocks
split parallel to stratification or along bedding planes.
Foliation plane is usually reffered as S plane.
The term has no genetic implications and may include sedimentary bedding
or igneous layering, etc.
7. Metamorphic foliations are divided into cleavages, schistosity and
gneissose structure.
1. Cleavage or rock cleavage – it is the property of rocks whereby they break
along approximately parallel surfaces of secondary origin. Cleavages are
foliations of secondary origin and usually parallel to bedding or inclined
to bedding. It is continuous cleavage or spaced cleavage. Slaty cleavage –
it is generally shown by slate due to parallel arrangement of platy minerals
lik mica, chlorite, etc.
.
Slaty cleavage
8. 2. Schistosity – secondary foliation developed by recrystallisation, in which
rocks tend to split along parallel planes and is the general property of
schist. Common in high grade metamorphic rocks.
3. Gneissosity / gneissic banding – in case of gneissosity, alternate silicic and
mafic layers are common. Mafic is shown by ferromagnesian minerals and
felsic by light coloured minerals.
9. Other types of foliation includes;-
Fracture cleavage – these are closely spaced joints. The distance between
fractures exceed a few cms. In fracture cleavage, an individual block are
bounded by fractures called microlithon.
Shear cleavage – it is synonym with slip cleavage. Fracture cleavage with
displacement. In the other hand, shear cleavages are closely spaced
fractures along with those has been some displacement.
Bedding cleavage – in some bedding plane, cleavage is parallel to the
bedding, it is called bedding cleavage/bedding schistosity.
Axial plane cleavage– those foliations that are parallel to the axial plane of
folds.
10. Lineations
It is the result of the parallelism of some directional property in the rock,
any linear feature that appears on the surface of the rock.
11. Primary lineation
It is found in both sedimentary and igneous rock and are formed along with
rock.
1. Linear flow structure – these are formed in igneous rocks as a result of
flowage of magma, longest axis of mineral align parallel to one another
and will be parallel to the flow direction.
2. Clots / aggregation – individual minerals when formed together clots may
develop, clots may allign parallel to themselves during the flowage of
magma.
3. Mineral lineation- linear parallelism of equigranular minerals develop
mineral lineation.
12. Secondary lineation
These are superimposed on rock after they are originally deposited,
erupted or intruded.
May be imposed more than once, so several lineation may be present in a
rock.
May occur with or without foliation, but more commonly, associated with
foliation.
A rock without cleavage or schistosity possess lineation.
13. 1. Elongated / stretched pebbles - They usually result from the elongation of
minerals or mineral aggregates (stretching lineations). Stretched pebbles
in deformed conglomerates is a common example.
2. Intersection lineation - Intersection of bedding and cleavage produces a
lineation. This is because the intersection of two planes is a line and if the
rocks break parallel to the cleavage, the trace of bedding appears as
parallel; streaks on cleavage.
14. 3. Slickenslides – polished striated surfaces that result from friction along the
fault plane. Scratches clearly indicate direction of movement.
15. 4. Boudinage or sausage structure – In cross section, a competent bed thickens
and thins to form a string of sausages. It is parallel to bedding, each unit
look like sausages lying side by side. Line of junction of individual units
may be called boudin line and this is a lineation. Boudin line may be
occupied by quartz, feldspar or other mineral. Boudinage a result of
stretching at right angles to boudin line.
16. 5. Pencil lineation – it is a very distinctive linear structure associated with
folded and cleaved mudstone and silt stones. It have a prefered orientation
and forms a lineation in unmetamorphosed and very low grade
metamorphic rocks.
6. Mullions - are linear deformation structure that are restricted to the
interface between a competent and incompetent rock.