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.
Chemostratigraphy is the study of chemical variations in sedimentary rocks to determine stratigraphic relationships. It uses inorganic geochemical data like carbon and oxygen isotopes to correlate rock layers. Oxygen isotopes fractionate with temperature changes and are measured in marine organism shells to create records for paleoclimate analysis. Carbon also has stable isotopes that provide information about past climate, evolution, and atmospheric CO2 levels. Chemostratigraphy has advantages over other correlation techniques as it can be used on any aged sediments regardless of lithology or environment. It has been applied successfully at major geologic boundaries and in unconventional reservoirs. Recent studies have also used sulfur and strontium isotopes to better understand changes around the Ordov
This document discusses the Precambrian geology of the Southern Granulite Terrain of India. It describes the terrain as being composed of several blocks separated by shear zones, which experienced high-grade metamorphism and multiple periods of folding and faulting. The metamorphic history involved ultra-high temperature conditions in some areas, as evidenced by mineral assemblages. The document also outlines two competing tectonic models to explain the evolution of the related Pandyan Mobile Belt: a subduction-collision model and an accretion model.
The document discusses lamprophyres, which are ultramafic, mafic, or intermediate intrusive rocks that form dikes or sills at shallow crustal levels. It covers the mineralogy, petrology, classification, occurrence in India, and economic importance of lamprophyres. Lamprophyres are classified into three main types - calc-alkaline, alkaline, and melilitic. Common lamprophyre types discussed include vogesites, minettes, spessartites, and kersantites. Lamprophyres in India are mostly found in Gondwana basins and some alkaline complexes. They can potentially contain diamonds or host gold mineralization.
This document discusses metamorphic differentiation, which refers to the redistribution of mineral grains or chemical components within a rock during metamorphism. There are two main types - segregation, which produces mineral-rich layers, and compositional layering parallel to metamorphic foliation. Gradients in chemical potential that drive differentiation are created by factors like temperature differences, pressure differences, mineral composition, mineral size, and the surrounding media. Mechanisms of differentiation include preserving original layering, transposing original bedding, solution and reprecipitation of minerals, preferential nucleation of minerals in fluids, and migmatization involving partial melting.
The document summarizes a seminar on carbonatites. Carbonatites are igneous rocks composed of more than 50% carbonate minerals such as calcite or dolomite. They can be intrusive or extrusive. Carbonatites form from low degrees of partial melting in the mantle and have unusual geochemistry dominated by incompatible elements. They are often associated with alkaline complexes and may contain economic concentrations of rare earth elements, niobium, and fluorite. The document outlines the mineralogy, texture, classification, geochemistry, theories of origin, world occurrences, and economic importance of carbonatites.
STUDY OF IMPORTANT METAMORPHIC ROCKS.pdfRITISHASINGH7
Study of important metamorphic rocks-
Petrological Characteristics, Indian Stratigraphic Position, Locality, Economic Importance and Facts about -
Granulite, Charnockite,
Eclogite, migmatites, Khondalite, Gondites.
Tectonites are deformed rocks whose fabric is due to systematic movement under external forces. Their fabric reflects the deformation history. Fabric includes the geometric arrangement of mineral grains, layers, and other features at a scale that includes many samples. Tectonites can have planar (S-tectonite), linear (L-tectonite), or both (L-S tectonite) fabrics indicating different strain types. Foliations like cleavage, schistosity, and gneissosity are planar fabrics that cause rocks to break along parallel surfaces. Lineations indicate preferred linear fabrics, such as fold axes, boudins, and quartz rods. The orientation and interaction of foliations and lineations provide information about tect
The document provides information on the Dharwar Craton located in southwest India. It discusses the classification of the craton into the Western Dharwar Craton (WDC) and Eastern Dharwar Craton (EDC). Key differences between the WDC and EDC are noted, including larger greenstone belts in the WDC surrounded by older gneiss, compared to narrower greenstone belts in the EDC intruded by a Dharwar Batholith. The lithology of the cratons is also summarized, including the Sargur Group, Bababudan Group, Chitradurga Group, and younger granites like the Closepet Granite. Regional structures, met
Chemostratigraphy is the study of chemical variations in sedimentary rocks to determine stratigraphic relationships. It uses inorganic geochemical data like carbon and oxygen isotopes to correlate rock layers. Oxygen isotopes fractionate with temperature changes and are measured in marine organism shells to create records for paleoclimate analysis. Carbon also has stable isotopes that provide information about past climate, evolution, and atmospheric CO2 levels. Chemostratigraphy has advantages over other correlation techniques as it can be used on any aged sediments regardless of lithology or environment. It has been applied successfully at major geologic boundaries and in unconventional reservoirs. Recent studies have also used sulfur and strontium isotopes to better understand changes around the Ordov
This document discusses the Precambrian geology of the Southern Granulite Terrain of India. It describes the terrain as being composed of several blocks separated by shear zones, which experienced high-grade metamorphism and multiple periods of folding and faulting. The metamorphic history involved ultra-high temperature conditions in some areas, as evidenced by mineral assemblages. The document also outlines two competing tectonic models to explain the evolution of the related Pandyan Mobile Belt: a subduction-collision model and an accretion model.
The document discusses lamprophyres, which are ultramafic, mafic, or intermediate intrusive rocks that form dikes or sills at shallow crustal levels. It covers the mineralogy, petrology, classification, occurrence in India, and economic importance of lamprophyres. Lamprophyres are classified into three main types - calc-alkaline, alkaline, and melilitic. Common lamprophyre types discussed include vogesites, minettes, spessartites, and kersantites. Lamprophyres in India are mostly found in Gondwana basins and some alkaline complexes. They can potentially contain diamonds or host gold mineralization.
This document discusses metamorphic differentiation, which refers to the redistribution of mineral grains or chemical components within a rock during metamorphism. There are two main types - segregation, which produces mineral-rich layers, and compositional layering parallel to metamorphic foliation. Gradients in chemical potential that drive differentiation are created by factors like temperature differences, pressure differences, mineral composition, mineral size, and the surrounding media. Mechanisms of differentiation include preserving original layering, transposing original bedding, solution and reprecipitation of minerals, preferential nucleation of minerals in fluids, and migmatization involving partial melting.
The document summarizes a seminar on carbonatites. Carbonatites are igneous rocks composed of more than 50% carbonate minerals such as calcite or dolomite. They can be intrusive or extrusive. Carbonatites form from low degrees of partial melting in the mantle and have unusual geochemistry dominated by incompatible elements. They are often associated with alkaline complexes and may contain economic concentrations of rare earth elements, niobium, and fluorite. The document outlines the mineralogy, texture, classification, geochemistry, theories of origin, world occurrences, and economic importance of carbonatites.
STUDY OF IMPORTANT METAMORPHIC ROCKS.pdfRITISHASINGH7
Study of important metamorphic rocks-
Petrological Characteristics, Indian Stratigraphic Position, Locality, Economic Importance and Facts about -
Granulite, Charnockite,
Eclogite, migmatites, Khondalite, Gondites.
Tectonites are deformed rocks whose fabric is due to systematic movement under external forces. Their fabric reflects the deformation history. Fabric includes the geometric arrangement of mineral grains, layers, and other features at a scale that includes many samples. Tectonites can have planar (S-tectonite), linear (L-tectonite), or both (L-S tectonite) fabrics indicating different strain types. Foliations like cleavage, schistosity, and gneissosity are planar fabrics that cause rocks to break along parallel surfaces. Lineations indicate preferred linear fabrics, such as fold axes, boudins, and quartz rods. The orientation and interaction of foliations and lineations provide information about tect
The document provides information on the Dharwar Craton located in southwest India. It discusses the classification of the craton into the Western Dharwar Craton (WDC) and Eastern Dharwar Craton (EDC). Key differences between the WDC and EDC are noted, including larger greenstone belts in the WDC surrounded by older gneiss, compared to narrower greenstone belts in the EDC intruded by a Dharwar Batholith. The lithology of the cratons is also summarized, including the Sargur Group, Bababudan Group, Chitradurga Group, and younger granites like the Closepet Granite. Regional structures, met
Fluid inclusions in metamorphic rocks provide information about fluids present during metamorphism. Fluid inclusions form when small portions of fluid get trapped in mineral crystals during their growth. Studies of fluid inclusions in South Indian granulites show they commonly contain CO2-rich fluids. Massive/banded charnockites from this region experienced high-grade metamorphism between 5-10.5 kbars and 550-880°C, indicating burial depths of 12-35 km. The quartz in these rocks contains primary and pseudosecondary CO2-rich inclusions with densities of 1.10-1.15 g/cc, providing evidence of the presence of CO2-rich fluids
The document discusses various processes of magmatic differentiation, including crystal-melt fractionation, physical separation of immiscible melts, and fluid-melt separation. It proposes that compositional convection within a boundary layer along the walls and top of a magma chamber can lead to in situ crystallization and development of compositional stratification faster than diffusion alone. As the magma cools and crystallizes from the margins inward, a gradient in the extent of crystallization develops. This produces a gradient in liquid composition, with more evolved liquids at the margins rising and spreading laterally beneath a stagnant cap, contributing to stratification.
The document discusses anorthosite, an intrusive igneous rock composed of 90-100% plagioclase feldspar. It describes the mineralogy, texture, and classification of anorthosite. Proteroic anorthosite formed during the Proterozoic era while Archean anorthosite formed during the Archean and are characterized by calcic plagioclase. Anorthosite is also found on the moon and classified as lunar anorthosite. Some anorthosite deposits are mined for titanium, iron, gemstones, and aluminum.
This document discusses various approaches to classifying igneous rocks. It describes classifications based on fabric (grain size, presence of glass), field relations (intrusive vs extrusive), mineralogical and modal compositions, and the 1973 IUGS modal classification system. It also addresses issues with using rock analyses to determine original magma compositions, noting that degassing can cause the volatile content of erupted rocks to be lower than the magma. Analyzing volatile content in melt inclusions in phenocrysts is presented as a way to determine a rock's pre-eruption magmatic volatile contents more accurately.
Hi I'm Misson Choudhury , A Post Graduate student, Graduated from Utkal university and Now pursuing my m.sc in applied geology at Bangalore university, Bangalore, i love geological mapping,drawing,hill climbing and tracking..
This document summarizes information about the Eastern Dharwar Craton (EDC) region of India. The EDC covers around 450,000 square kilometers and contains several greenstone belts formed from volcanic and sedimentary rocks. It is bounded by mobile belts and separated from the Western Dharwar Craton by the Chitradurga Shear Zone. The EDC contains older gneissic basement rocks overlain by the Warangal Group and greenstone belts of the Dharwar Supergroup, along with the large Closepet Granite intrusion and regions metamorphosed to amphibolite and granulite facies.
This document provides an overview of kimberlites, including their mineralogy, morphology, petrology, classification, origin, and economic importance. Kimberlites occur as vertical carrot-shaped intrusions called pipes and have an inequigranular texture consisting of large crystals in a fine-grained matrix. They are classified into Group I and Group II based on isotopic affinities. Kimberlites originate at depths of 100-200 km in the mantle and are emplaced explosively due to their high volatile content, forming diatremes with features like angular fragments. Kimberlites are economically important as the primary source of diamonds, though only 1 in 200 pipes contain gem-quality diamonds.
The document discusses the Western Dharwar Craton located in peninsular India. It is bounded by mobile belts and contains various rock groups like the Sargur, Bababudan, and Chitradurga groups. The oldest rocks are the Gorur gneisses dated to 3500-3600 million years ago. Younger granites and schist belts containing ultramafic and mafic rocks cut across the craton. The economic deposits in the area include magnesite, iron, chromium, vanadium, and copper-nickel ores. The craton shows increasing metamorphic grade from greenschist in the north to amphibolite and granulite facies in the south.
The document provides an overview of the Paleozoic era, which began approximately 542 million years ago and lasted around 290 million years. Some key points:
- Suitable time for organic evolution of both flora and fauna. Rocks from this era are less deformed, providing good sections for research.
- In India, Paleozoic rocks are mainly found in the Himalayan region and isolated basins in the peninsula. Stratigraphy has been determined along river sections in the Himalayas.
- Life included early plants, foraminifera, corals, brachiopods, pelecypods, gastropods, cephalopods, ostracods
The Stratigraphic Code establishes rules for naming and defining stratigraphic units. There are two versions of the code from the North American and International commissions. Stratigraphic units are categorized based on physical characteristics and time, and include lithostratigraphic, biostratigraphic, magnetostratigraphic, and others. Proper naming of a new unit requires publication and establishing type sections and boundaries.
Lithostratigraphy is the subdivision of rock layers based on their lithology or rock type. Rock layers are divided into standardized units including supergroups, groups, formations, and members. Lithostratigraphic units are defined solely based on distinct rock compositions and types. Boundaries between lithostratigraphic units are placed at points of clear lithological changes, either where rock types sharply differ or where gradational changes allow arbitrary boundaries. The basic hierarchy of lithostratigraphic units ranked from highest to lowest includes supergroups, groups, and members.
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.
This document defines sequence stratigraphy and discusses its basic concepts. Sequence stratigraphy studies genetically related rock units bounded by unconformities. It is based on dividing strata into sequences bounded by sea level changes. Key concepts discussed include depositional sequences, parasequences, flooding surfaces, system tracts, accommodation space, and the importance of sequence stratigraphy for understanding basin evolution and resource exploration.
The document summarizes the geology of the Bundelkhand craton located in central India. The craton covers an area of 26,000 square kilometers and contains three main components: enclaves of supracrustal rocks within older gneisses, the Bundelkhand granite and associated quartz reefs and volcanic rocks, and mafic dyke swarms. The craton has undergone tectonic evolution characterized by three primary shear zone orientations: east-west, northeast-southwest, and northwest-southeast.
Paired metamorphic belts occur where zones of high-pressure low-temperature metamorphism are parallel to zones of low-pressure high-temperature metamorphism. They were first recognized in Japan and form due to subduction of oceanic crust beneath continental crust. Paired metamorphic belts support the theory of plate tectonics, as the contrasting pressure-temperature conditions in the two parallel belts can be explained by ocean-continent convergence. Examples of paired metamorphic belts are found throughout the basement rocks of the former Gondwanaland supercontinent.
This document discusses various criteria that can be used to determine the top and bottom of sedimentary beds and identify the relative age of rock layers. Some key criteria mentioned include unconformities, fossils, ripple marks, cross-bedding, graded bedding, and the position of cleavage in folded rocks. Law of superposition, which states that older beds are deposited first and therefore located lower in the stratigraphic column, is also discussed. Together, these criteria can be used to deduce the order of deposition and effects of tilting, folding, or other deformation on sedimentary beds.
Sequence stratigraphy and its applicationsPramoda Raj
Sequence stratigraphy is the study of rock strata in terms of depositional sequences that are genetically related and bounded by unconformities or correlative conformities. It was pioneered by James Hutton in 1788 and further developed by researchers like Sloss and Vail to understand global eustatic sea level changes and their control on sediment deposition. Key concepts include systems tracts like transgressive, highstand, and parasequences which are building blocks of sequences. Sequence stratigraphy is useful for basin analysis, hydrocarbon exploration, and understanding past sea level fluctuations. Case studies have applied it to outcrops and subsurface sediments.
"Granites" Classification, Petrogenesis and Tectonic DescriminationSamir Kumar Barik
This document discusses the classification, petrogenesis, and tectonic discrimination of granites. It begins with definitions of granite and descriptions of its typical mineralogical and textural characteristics. It then outlines several common classification schemes for granites based on mineralogy, chemistry, and tectonic setting. These include QAPF, alumina saturation, S-I-A-M, and discriminations based on plate tectonic setting. The document also discusses models for the petrogenesis of granites involving magmatic differentiation and metasomatic processes. Geochemical discrimination diagrams are presented and the multiple possible origins of granites are noted. Future work on the geochemistry and uranium mineralization of granites in specific
Rock layers are formed through sedimentary processes over long periods of time. Stratified rocks are formed from sediments laid down in layers, and their formation depends on stratigraphy and stratification. There are several laws of stratigraphy that help geologists determine the relative ages of rock layers based on principles like original horizontality, superposition, cross-cutting relationships, inclusions and unconformities. Geologists use physical features of the rock layers as well as index fossils to correlate and match rock layers across different regions in order to reconstruct Earth's history.
Fluid inclusions in metamorphic rocks provide information about fluids present during metamorphism. Fluid inclusions form when small portions of fluid get trapped in mineral crystals during their growth. Studies of fluid inclusions in South Indian granulites show they commonly contain CO2-rich fluids. Massive/banded charnockites from this region experienced high-grade metamorphism between 5-10.5 kbars and 550-880°C, indicating burial depths of 12-35 km. The quartz in these rocks contains primary and pseudosecondary CO2-rich inclusions with densities of 1.10-1.15 g/cc, providing evidence of the presence of CO2-rich fluids
The document discusses various processes of magmatic differentiation, including crystal-melt fractionation, physical separation of immiscible melts, and fluid-melt separation. It proposes that compositional convection within a boundary layer along the walls and top of a magma chamber can lead to in situ crystallization and development of compositional stratification faster than diffusion alone. As the magma cools and crystallizes from the margins inward, a gradient in the extent of crystallization develops. This produces a gradient in liquid composition, with more evolved liquids at the margins rising and spreading laterally beneath a stagnant cap, contributing to stratification.
The document discusses anorthosite, an intrusive igneous rock composed of 90-100% plagioclase feldspar. It describes the mineralogy, texture, and classification of anorthosite. Proteroic anorthosite formed during the Proterozoic era while Archean anorthosite formed during the Archean and are characterized by calcic plagioclase. Anorthosite is also found on the moon and classified as lunar anorthosite. Some anorthosite deposits are mined for titanium, iron, gemstones, and aluminum.
This document discusses various approaches to classifying igneous rocks. It describes classifications based on fabric (grain size, presence of glass), field relations (intrusive vs extrusive), mineralogical and modal compositions, and the 1973 IUGS modal classification system. It also addresses issues with using rock analyses to determine original magma compositions, noting that degassing can cause the volatile content of erupted rocks to be lower than the magma. Analyzing volatile content in melt inclusions in phenocrysts is presented as a way to determine a rock's pre-eruption magmatic volatile contents more accurately.
Hi I'm Misson Choudhury , A Post Graduate student, Graduated from Utkal university and Now pursuing my m.sc in applied geology at Bangalore university, Bangalore, i love geological mapping,drawing,hill climbing and tracking..
This document summarizes information about the Eastern Dharwar Craton (EDC) region of India. The EDC covers around 450,000 square kilometers and contains several greenstone belts formed from volcanic and sedimentary rocks. It is bounded by mobile belts and separated from the Western Dharwar Craton by the Chitradurga Shear Zone. The EDC contains older gneissic basement rocks overlain by the Warangal Group and greenstone belts of the Dharwar Supergroup, along with the large Closepet Granite intrusion and regions metamorphosed to amphibolite and granulite facies.
This document provides an overview of kimberlites, including their mineralogy, morphology, petrology, classification, origin, and economic importance. Kimberlites occur as vertical carrot-shaped intrusions called pipes and have an inequigranular texture consisting of large crystals in a fine-grained matrix. They are classified into Group I and Group II based on isotopic affinities. Kimberlites originate at depths of 100-200 km in the mantle and are emplaced explosively due to their high volatile content, forming diatremes with features like angular fragments. Kimberlites are economically important as the primary source of diamonds, though only 1 in 200 pipes contain gem-quality diamonds.
The document discusses the Western Dharwar Craton located in peninsular India. It is bounded by mobile belts and contains various rock groups like the Sargur, Bababudan, and Chitradurga groups. The oldest rocks are the Gorur gneisses dated to 3500-3600 million years ago. Younger granites and schist belts containing ultramafic and mafic rocks cut across the craton. The economic deposits in the area include magnesite, iron, chromium, vanadium, and copper-nickel ores. The craton shows increasing metamorphic grade from greenschist in the north to amphibolite and granulite facies in the south.
The document provides an overview of the Paleozoic era, which began approximately 542 million years ago and lasted around 290 million years. Some key points:
- Suitable time for organic evolution of both flora and fauna. Rocks from this era are less deformed, providing good sections for research.
- In India, Paleozoic rocks are mainly found in the Himalayan region and isolated basins in the peninsula. Stratigraphy has been determined along river sections in the Himalayas.
- Life included early plants, foraminifera, corals, brachiopods, pelecypods, gastropods, cephalopods, ostracods
The Stratigraphic Code establishes rules for naming and defining stratigraphic units. There are two versions of the code from the North American and International commissions. Stratigraphic units are categorized based on physical characteristics and time, and include lithostratigraphic, biostratigraphic, magnetostratigraphic, and others. Proper naming of a new unit requires publication and establishing type sections and boundaries.
Lithostratigraphy is the subdivision of rock layers based on their lithology or rock type. Rock layers are divided into standardized units including supergroups, groups, formations, and members. Lithostratigraphic units are defined solely based on distinct rock compositions and types. Boundaries between lithostratigraphic units are placed at points of clear lithological changes, either where rock types sharply differ or where gradational changes allow arbitrary boundaries. The basic hierarchy of lithostratigraphic units ranked from highest to lowest includes supergroups, groups, and members.
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.
This document defines sequence stratigraphy and discusses its basic concepts. Sequence stratigraphy studies genetically related rock units bounded by unconformities. It is based on dividing strata into sequences bounded by sea level changes. Key concepts discussed include depositional sequences, parasequences, flooding surfaces, system tracts, accommodation space, and the importance of sequence stratigraphy for understanding basin evolution and resource exploration.
The document summarizes the geology of the Bundelkhand craton located in central India. The craton covers an area of 26,000 square kilometers and contains three main components: enclaves of supracrustal rocks within older gneisses, the Bundelkhand granite and associated quartz reefs and volcanic rocks, and mafic dyke swarms. The craton has undergone tectonic evolution characterized by three primary shear zone orientations: east-west, northeast-southwest, and northwest-southeast.
Paired metamorphic belts occur where zones of high-pressure low-temperature metamorphism are parallel to zones of low-pressure high-temperature metamorphism. They were first recognized in Japan and form due to subduction of oceanic crust beneath continental crust. Paired metamorphic belts support the theory of plate tectonics, as the contrasting pressure-temperature conditions in the two parallel belts can be explained by ocean-continent convergence. Examples of paired metamorphic belts are found throughout the basement rocks of the former Gondwanaland supercontinent.
This document discusses various criteria that can be used to determine the top and bottom of sedimentary beds and identify the relative age of rock layers. Some key criteria mentioned include unconformities, fossils, ripple marks, cross-bedding, graded bedding, and the position of cleavage in folded rocks. Law of superposition, which states that older beds are deposited first and therefore located lower in the stratigraphic column, is also discussed. Together, these criteria can be used to deduce the order of deposition and effects of tilting, folding, or other deformation on sedimentary beds.
Sequence stratigraphy and its applicationsPramoda Raj
Sequence stratigraphy is the study of rock strata in terms of depositional sequences that are genetically related and bounded by unconformities or correlative conformities. It was pioneered by James Hutton in 1788 and further developed by researchers like Sloss and Vail to understand global eustatic sea level changes and their control on sediment deposition. Key concepts include systems tracts like transgressive, highstand, and parasequences which are building blocks of sequences. Sequence stratigraphy is useful for basin analysis, hydrocarbon exploration, and understanding past sea level fluctuations. Case studies have applied it to outcrops and subsurface sediments.
"Granites" Classification, Petrogenesis and Tectonic DescriminationSamir Kumar Barik
This document discusses the classification, petrogenesis, and tectonic discrimination of granites. It begins with definitions of granite and descriptions of its typical mineralogical and textural characteristics. It then outlines several common classification schemes for granites based on mineralogy, chemistry, and tectonic setting. These include QAPF, alumina saturation, S-I-A-M, and discriminations based on plate tectonic setting. The document also discusses models for the petrogenesis of granites involving magmatic differentiation and metasomatic processes. Geochemical discrimination diagrams are presented and the multiple possible origins of granites are noted. Future work on the geochemistry and uranium mineralization of granites in specific
Rock layers are formed through sedimentary processes over long periods of time. Stratified rocks are formed from sediments laid down in layers, and their formation depends on stratigraphy and stratification. There are several laws of stratigraphy that help geologists determine the relative ages of rock layers based on principles like original horizontality, superposition, cross-cutting relationships, inclusions and unconformities. Geologists use physical features of the rock layers as well as index fossils to correlate and match rock layers across different regions in order to reconstruct Earth's history.
This document provides an overview of key concepts related to cleavage, foliation, and lineation in metamorphic rocks. It defines different types of cleavage based on scale, including slaty, phyllitic, and schistosity. It also discusses crenulation and spaced cleavage. Examples are provided of slate, phyllite, schistosity, and crenulation cleavage in metamorphic rocks. The document also discusses concepts such as boudinage, gneissic structure, migmatization, mylonite, and different types of lineations. It provides examples of strain markers and describes analyzing strain in strongly deformed rocks. Finally, it discusses relationships between deformation, metamorphism, pl
This document defines and classifies different types of foliation in metamorphic rocks. It begins by defining foliation as a planar or curvi-planar fabric formed in metamorphic rocks. Foliations are classified genetically as primary, secondary, or inherited, and morphologically as spaced, continuous, or disjunctive. Key types of secondary foliation include cleavage, schistosity, slip cleavage, and shear cleavage. Foliations provide important information about the tectonic and metamorphic evolution of an area and help determine the geometry of folding. Different foliation types reflect variations in lithology and temperature during metamorphism and deformation.
Rock layers are formed through sedimentary processes over long periods of time. Sediments are deposited in layers and compacted into sedimentary rock. The law of superposition states that older rock layers are below younger rock layers. Stratigraphy studies the order and ages of rock layers. Geologists use several principles including cross-cutting relationships, inclusions, and index fossils to correlate and date rock layers between different regions.
Joints are fractures in rocks that divide the rock mass into blocks. There are three main types of joints based on their orientation: strike joints parallel to bedding, dip joints parallel to slope, and oblique joints with other orientations. Joints are classified based on their pattern, geometry, and origin. Unconformities represent gaps or erosional surfaces in the geological record where rock layers are missing. The main types are angular, disconformity, and nonconformity. Both joints and unconformities are important in engineering projects as they can impact stability, water flow, and excavation difficulties.
The document discusses how rock layers are formed through sedimentary processes and stratification over geological time. It explains James Hutton's principle of uniformitarianism, which states that current geological processes can explain the evolution of Earth's surface. Rock layers are formed through the deposition and compaction of sediments in visible layers. Stratigraphy studies the description and interpretation of stratified rocks. Key laws of stratigraphy discussed are superposition, original horizontality, cross-cutting relationships, and faunal succession. Correlating rock layers between locations allows geologists to construct a more complete geological record.
This document discusses key concepts in stratigraphy, including:
- Stratigraphy deals with rock succession through time and space, telling the story of the Earth's history.
- There are different types of stratigraphy based on lithology, time, fossils, magnetism, and seismic characteristics.
- Stratification is based on principles like superposition, original horizontality, lateral continuity, and cross-cutting relationships.
- Unconformities represent gaps in the geologic record where no rocks were deposited for long periods of time.
Shear zones are zones of highly strained rock that form under brittle, ductile, or intermediate conditions. They record a history of deformation and can indicate the sense and amount of displacement. There are several types of shear zones defined by the dominant deformation mechanism (brittle, ductile, semibrittle, brittle-ductile). Determining the sense of shear is important and can be achieved through studying offset markers, foliation patterns, shear bands, inclusion shapes, and other indicators exposed in the shear zone.
Structural geology is the study of rock structures and deformations within the Earth's crust. There are several types of rock structures that provide evidence of past deformation, including folds, faults, joints, and foliations. Folds occur when rock layers are bent, and there are different types such as anticlines, synclines, tight folds, overfolds, recumbent folds, and nappe folds. Understanding rock structures provides insight into the stress fields and tectonic processes that shaped the geological past.
Analysis and interpretation of foliation and lineationPramoda Raj
Foliation and lineation are important fabric elements in structural geology. Foliation refers to any closely spaced planar structures in rocks, such as layering, and develops through processes like deformation and metamorphism. There are different types of foliation including primary, diagenetic, and secondary foliation. Lineation describes any linear structures in rocks, such as the alignment of minerals, and develops through processes associated with folds, boudins, and the intersection of planar fabrics. Foliation and lineation provide insight into the tectonic and metamorphic evolution of geological areas.
Lineation refers to any linear structure that occurs repetitively in rock, such as elongated pebbles or the intersection of two foliations. Lineations can indicate the direction of tectonic transport, though opinions differ on whether they are parallel or perpendicular to transport. Foliation refers to repetitive layering in metamorphic rocks caused by shearing forces or pressure differences. Types of foliation include fracture cleavage, crenulation cleavage, slaty cleavage, and schistosity. Lineations and foliations provide important clues about a rock's deformation history.
- 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.
This document discusses how rock layers are formed through sedimentary processes and stratified over time. It explains key principles of stratigraphy used to study and correlate rock layers, including:
- The law of superposition states that oldest layers are on the bottom and youngest on top.
- Principles of original horizontality and inclusions help determine if layers have been disturbed.
- The law of cross-cutting relationships and unconformities show periods where deposition stopped and erosion occurred.
- Fossils are used to correlate rock layers between locations based on identifying index fossils of a specific short time period. Physical characteristics can also help correlate rock layers.
This document discusses structural geography and stratigraphy. It defines structural geography as the study of dip, strike, outcrops, inliers, outliers, discontinuities, folds, faults, joints and unconformities in rock structures. Stratigraphy is divided into lithostratigraphy, which studies rock layers based on lithology, and biostratigraphy, which uses fossil assemblages to correlate rock ages. The principles of stratigraphy include original horizontality, superposition, lateral continuity, cross-cutting relationships, inclusions, faunal succession, and uniformitarianism. Types of stratigraphy are lithostratigraphy, chronostratigraphy, biostratigraphy, magnetostratigraphy, allostratigraphy, geochron
CORRELATION-OF-ROCK-LAYERS ELS GRADE 12.pptxJohnKennethPea
Geologists correlate rock layers between different locations by matching characteristics like composition, texture, fossils, and stratigraphic position. Correlation allows geologists to reconstruct a complete geological record even when no single location preserves a full, continuous sequence of rock layers due to erosion or gaps in deposition. Key methods of correlation include comparing rock types and index fossils, and applying principles like superposition and lateral continuity to match layers between columns. Matching correlated layers establishes their relative ages and allows geologists to estimate the original geographic extent of ancient rock units.
This document discusses different aspects of structural geology and stratigraphy. It describes joints as fractures in rocks where there has been no relative displacement of the rock blocks. It defines different types of joints like open joints, closed joints, sheet joints, columnar joints, and bedding joints. It also classifies joints as tension joints, shear joints, and compression joints. The document then discusses unconformities as gaps in rock layers formed due to periods of erosion or non-deposition. It describes different types of unconformities like angular unconformities, disconformities, local unconformities, nonconformities, and regional unconformities.
A fabric describes the spatial and geometric relationships that make up a rock at the microscopic to centimeter scale. It includes planar structures like bedding and cleavage, as well as the preferred orientation of minerals. There are different types of fabric including linear fabric formed by elongate minerals, planar fabric formed by platy minerals, and random fabric with no orientation. Foliation specifically refers to any planar arrangement of minerals or structures in a rock. Foliation can be primary, forming during rock formation, or secondary, resulting from deformation. Common types of secondary foliation include cleavage, schistosity, and mylonitic foliation. Lineation describes a preferred linear orientation of features in a rock, often related to deformation processes like intersection of planar
The document discusses how topographic maps in India are organized and identified using a hierarchical system of map sheets with different scales. Topographic maps are divided into million sheet sections at 1:1,000,000 scale, degree sheets at 1:250,000 scale, toposheets at 1:50,000 scale, and further subdivided toposheets at 1:25,000 scale that are identified by letters and numbers corresponding to their location and scale. This system allows precise identification of location for any place shown on topographic maps in India.
Gravity anomaly across reagional structuresAmit K. Mishra
Gravity Anomaly across continents and ocean, gravity anomaly across mid-oceanic ridges, gravity anomaly across orogenic belts, and gravity anomaly across subduction zones.
Earth is not a perfect sphere, but is classified as an oblate spheroid, or ellipsoid. It is flattened at the poles and bulges at the equator due to centrifugal forces from its rotation. Its equatorial diameter is 7,926 miles while the polar diameter is 7,900 miles. Modern analyses use precise satellite observations to define the International Reference Ellipsoid, which models Earth as an oblate spheroid with an equatorial radius of 6378.137 km and polar radius of 6356.752 km.
This document is a field training report submitted by Ms. Rohini Singh to Banasthali University in partial fulfillment of an M.Sc. in geology. The report provides an introduction to the geology of the Kachchh region of Gujarat, India where the field training took place. It describes the physiographic divisions and stratigraphy of the Kachchh basin, including the Mesozoic, Tertiary, and Quaternary units. It also discusses the tectonic settings of the basin and the major fault systems, including the Kachchh Mainland Fault and South Wagad Fault.
This Lecture includes the Resistivity survey, field procedure, application advantage, limitaion, Apparant resistivity, VES (Vertical Electrical Sounding), Resistivity Profiling and IP Survey in brief.
The Lectures describes the Electrical method of Geophysical Prospecting in brief. SP surveying and Occurrence of Self potential and its application is discussed in brief.
This topic includes representation of topography by various non mathematical and mathematical methods.
Pictorial method (Hachure lines, Hill shading)
Mathematical method (Spot heights,Bench marks, Trigonometrical stations, Layer tint or altitude tints, Contour lines )
Combination of different methods
This lecture includes the fold terminology and classification of folds based of different criteria.
Classification of folds based on:
Direction of closing
Attitude of axial surface
Size of interlimb angle
Profile
Ramsay Classification of folds
This notes provide the information about tectonic divisions and evolution of Himalayas. movement of Indian plate has also taken up in brief.
Tectonic Division of Himalaya
Evolution of Himalaya
Movement of Indian Plate.
Resource description_ Rasoul Sorkhabi, The himalayan Journal, 2010
Mantle plumes are hypothesized to be long, nearly vertical columns of hot material that rise from deep within the Earth's mantle. At the surface, plumes are marked by volcanic hotspots with high heat flow. As tectonic plates move over fixed mantle plumes, they leave behind linear chains of volcanoes. Evidence for mantle plumes includes zones of volcanism and crustal uplift far from plate boundaries, geochemical signatures of basalts that differ from mid-ocean ridge basalts, and seismic tomography images showing narrow columns of low-velocity material extending deep into the mantle. Plumes are thought to originate at the core-mantle boundary and rise through the mantle as bulbous heads fed by narrow tails,
The document discusses plate tectonics and the evidence that supports the theory. It describes how Alfred Wegener first proposed the idea of continental drift in 1915, noting that continents seem to fit together. Over decades, further evidence was collected from matching fossil records, mountain ranges, and coastline shapes between separated continents. In the 1960s, the theory of plate tectonics emerged to explain these observations, proposing that the Earth's lithosphere is broken into plates that move over Earth's asthenosphere. There are three types of plate boundaries - divergent where new crust forms, convergent where plates collide, and transform where plates slide past each other.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
Microbial interaction
Microorganisms interacts with each other and can be physically associated with another organisms in a variety of ways.
One organism can be located on the surface of another organism as an ectobiont or located within another organism as endobiont.
Microbial interaction may be positive such as mutualism, proto-cooperation, commensalism or may be negative such as parasitism, predation or competition
Types of microbial interaction
Positive interaction: mutualism, proto-cooperation, commensalism
Negative interaction: Ammensalism (antagonism), parasitism, predation, competition
I. Mutualism:
It is defined as the relationship in which each organism in interaction gets benefits from association. It is an obligatory relationship in which mutualist and host are metabolically dependent on each other.
Mutualistic relationship is very specific where one member of association cannot be replaced by another species.
Mutualism require close physical contact between interacting organisms.
Relationship of mutualism allows organisms to exist in habitat that could not occupied by either species alone.
Mutualistic relationship between organisms allows them to act as a single organism.
Examples of mutualism:
i. Lichens:
Lichens are excellent example of mutualism.
They are the association of specific fungi and certain genus of algae. In lichen, fungal partner is called mycobiont and algal partner is called
II. Syntrophism:
It is an association in which the growth of one organism either depends on or improved by the substrate provided by another organism.
In syntrophism both organism in association gets benefits.
Compound A
Utilized by population 1
Compound B
Utilized by population 2
Compound C
utilized by both Population 1+2
Products
In this theoretical example of syntrophism, population 1 is able to utilize and metabolize compound A, forming compound B but cannot metabolize beyond compound B without co-operation of population 2. Population 2is unable to utilize compound A but it can metabolize compound B forming compound C. Then both population 1 and 2 are able to carry out metabolic reaction which leads to formation of end product that neither population could produce alone.
Examples of syntrophism:
i. Methanogenic ecosystem in sludge digester
Methane produced by methanogenic bacteria depends upon interspecies hydrogen transfer by other fermentative bacteria.
Anaerobic fermentative bacteria generate CO2 and H2 utilizing carbohydrates which is then utilized by methanogenic bacteria (Methanobacter) to produce methane.
ii. Lactobacillus arobinosus and Enterococcus faecalis:
In the minimal media, Lactobacillus arobinosus and Enterococcus faecalis are able to grow together but not alone.
The synergistic relationship between E. faecalis and L. arobinosus occurs in which E. faecalis require folic acid
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
CLASS 12th CHEMISTRY SOLID STATE ppt (Animated)eitps1506
Description:
Dive into the fascinating realm of solid-state physics with our meticulously crafted online PowerPoint presentation. This immersive educational resource offers a comprehensive exploration of the fundamental concepts, theories, and applications within the realm of solid-state physics.
From crystalline structures to semiconductor devices, this presentation delves into the intricate principles governing the behavior of solids, providing clear explanations and illustrative examples to enhance understanding. Whether you're a student delving into the subject for the first time or a seasoned researcher seeking to deepen your knowledge, our presentation offers valuable insights and in-depth analyses to cater to various levels of expertise.
Key topics covered include:
Crystal Structures: Unravel the mysteries of crystalline arrangements and their significance in determining material properties.
Band Theory: Explore the electronic band structure of solids and understand how it influences their conductive properties.
Semiconductor Physics: Delve into the behavior of semiconductors, including doping, carrier transport, and device applications.
Magnetic Properties: Investigate the magnetic behavior of solids, including ferromagnetism, antiferromagnetism, and ferrimagnetism.
Optical Properties: Examine the interaction of light with solids, including absorption, reflection, and transmission phenomena.
With visually engaging slides, informative content, and interactive elements, our online PowerPoint presentation serves as a valuable resource for students, educators, and enthusiasts alike, facilitating a deeper understanding of the captivating world of solid-state physics. Explore the intricacies of solid-state materials and unlock the secrets behind their remarkable properties with our comprehensive presentation.
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...Travis Hills MN
By harnessing the power of High Flux Vacuum Membrane Distillation, Travis Hills from MN envisions a future where clean and safe drinking water is accessible to all, regardless of geographical location or economic status.
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...
Fabric elements
1.
2. INTRODUCTION
• In everyday language, we commonly use the word
“fabric.”
• When talking about fabrics that are used to
make garments, we mean a patterned cloth made by
weaving fibers in some geometric arrangement. But
the word “fabric” is not used only to refer to material
products.
• In a philosophical moment we might consider the “fabric
of life,” by which we mean the underlying organization
of life.
3. • As we found to be the case with many terms, the word fabric has a related yet
somewhat different meaning in geology.
• To a structural geologist, the 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
• It may sound picky, but structural geologists also make a distinction between
microstructure and texture.
• Although texture is sometimes used as a synonym for microstructure, for
example igneous texture, here we restrict the term texture to crystallographic
orientation patterns in an aggregate of and microstructure to their geometric
arrangement.
4. • Tectonic fabrics provide clues to the :
strain state of the rock,
the geometry of associated folding,
The processes involved in deformation,
the kinematics of deformation,
the timing of deformation (if the fabric is defined by an
arrangement of datable minerals),
and ultimately about the tectonic evolution of a region.
• The purpose of this lecture is to explore two common
tectonic fabric elements in rocks, foliations and lineations,
and to introduce you to the characteristics and
interpretation of these elements.
5. FABRIC TERMINOLOGY
• Let’s start by developing the inevitable vocabulary to
discuss tectonic fabrics (see Table 11.1).
• If there is no preferred orientation (i.e., alignment) of
the fabric elements, then we say that the rock has a
random fabric (Figure 11.1a). Undeformed sandstone,
granite, or basalt are rocks with random fabrics.
• Deformed rocks typically have a nonrandom fabric or
a preferred fabric, in which the fabric elements are
aligned in some manner and/or are repeated at an
approximately regular spacing (Figure 11.1b).
6.
7. • There are two main classes of preferred fabrics in rock.
A planar fabric, or foliation (Figure 11.1c), is one in
which the fabric element is a planar or tabular feature
(meaning it is shorter in one dimension than in the other
two), and a linear fabric, or lineation (Figure 11.1d), is
one in which the fabric element is effectively a linear
feature (i.e., it is longer in one dimension relative to the
other dimensions).
• Structural geologists may use the word “fabric” alone
to imply the existence of a preferred fabric (as in, “that
rock has a strong fabric”), but you should use
appropriate modifiers if your meaning is not clear from
context alone.
8. • We’re not quite done with terminology yet! Fabrics are
complicated features, and there are lots of different
adjectives used by structural geologists to describe them.
• For example, if you can keep splitting the rock into smaller
and smaller pieces, right down to the size of the component
grains, and can still identify a preferred fabric, then we say
that the fabric is continuous.
• In practice, 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. (Figure 11.2b)
9.
10. Tectonites
• Rocks with a penetrative tectonic fabric are also called
tectonites.
• When linear fabric elements dominate, the rock is called an L-
tectonite, whereas a rock with dominantly planar fabrics is
called an S-tectonite, and, not surprisingly, rocks with both
types of fabric elements are called LS-tectonites.
11. • Typically, the deformation that leads to the
formation of a tectonite is accompanied by
metamorphism, so the fabric is defined by
grains that have been partially or totally
recrystallized , and/or by new minerals that
have grown during deformation (called
neomineralization).
• Because most rocks are deformed, tectonites
are among the most common rocks you will
see (Figure 11.4); some examples are slates,
schists, and mylonites
12. FOLIATIONS
• A foliation is any type of planar fabric in a rock. We are admittedly a bit loose
in our use of the term planar. Since, strictly speaking, a plane does not contain
any curves or changes in orientation, the terms curviplanaror surface would be
more appropriate.
• Although foliations are generally not perfectly planar, structural geologogists
nonetheless are in the habit of talking about planar fabrics. Thus, bedding,
cleavage, schistosity, and gneissosity all qualify as foliations.
• Fractures, however, are not considered to be foliations, because fractures are
breaks through a rock and are not a part of the rock itself.
• A rock may contain several foliations, especially if it has been deformed more
than once. To keep track of different foliations, geologists add subscripts to the
foliations: S0, S1, S2, and so on. S0 is used to refer to bedding, S1 is the first
foliation formed after bedding, and S2 forms after S1.
• The temporal sequence of foliation development is defined by cross-cutting
relationships, but in complexly deformed areas, it may be quite a challenge to
determine which foliation is which unless independent constraints on (relative)
time are available.
13. • There are many types of tectonic foliations that are
distinguished from one another simply on the basis of what
they look like.
• The physical appearance of a foliation reflects the process
by which it formed, and the process, in turn, is controlled
partly by the composition and grain size of the original
lithology, and partly by the metamorphic conditions under
which the foliation formed.
• Different names are used for the different types of
foliations. In Table 11.2 and the following discussion, we
will introduce different types of foliation roughly in
sequence of increasingly higher metamorphic conditions—
cleavage first, then schistosity, then gneissic layering.
14.
15. What Is Cleavage?
• A secondary fabric element, formed under low-temperature conditions,
that imparts on the rock a tendency to split along planes.
The point of this definition is to emphasize
1. That cleavage is a feature of the rock that forms subsequent to the origin
of the rock.
2. That the term “cleavage” is used, in practice, for tectonic planar fabrics
formed at or below lower green-schist facies conditions (i.e., ≤ 300°C).
The term “cleavage” is not used when referring to the fabric in schists or
in gneiss.
3. That in a rock with cleavage, there are planes of weakness across which
the rock may later break when uplifted and exposed at the surface of the
earth, even though cleavage itself forms without loss of cohesion. By this
definition, an array of closely spaced fractures is not a cleavage.
16. • We recognize four main categories of cleavage
that are differentiated from one another by their
morphological characteristics (or, by how they
look in outcrop). These are disjunctive cleavage,
pencil cleavage, slaty cleavage, and crenulation
cleavage.
17. Disjunctive Cleavage
• Disjunctive cleavage is a foliation that forms mostly
in sedimentary rocks that have been subjected to a
tectonic differential stress under sub–greenschist
facies metamorphic conditions.
• It is defined by an array of subparallel fabric elements,
called cleavage domains, in which the original rock
fabric and composition have been markedly changed by
the process of pressure solution.
• Domains are separated from one another by intervals,
called microlithons, in which the original rock fabric
and composition are more or less preserved
18. • The adjective “disjunctive” implies that the
cleavage domains cut across a preexisting
foliation in the rock (usually bedding), without
affecting the orientation of the preexisting
foliation in the microlithons.
• Because pressure solution is always involved
in the formation of a disjunctive cleavage,
other terms such as (pressure-)solution
cleavage and stylolitic cleavage have been
used for this structure.
19.
20. • If the context is clear, some geologists may refer to the
structure simply as spaced cleavage, though, as we see
later, crenulation cleavage is also a type of spaced
cleavage. Earlier in this century, many geologists
incorrectly considered cleavage domains to be brittle
fractures formed by loss of cohesion. The old term
“fracture cleavage” should therefore be avoided when
referring to disjunctive cleavage, because a cleavage
cannot be composed of fractures. Such arrays of
closely spaced fractures should be called a fracture or
joint array.
21. Pencil Cleavage
• If a fine-grained sedimentary rock (shale or mudstone)
breaks into elongate pencil-like shards because of its
internal fabric, we say that it has a pencil cleavage
(Figure 11.8).
• Typically, pencils are 5–10 cm long and 0.5–1 cm in width.
• In outcrop, pencil cleavage looks as if it results from the interaction
of two fracture sets (and in some locations, it is indeed merely a
consequence of the intersection between a fracture set and bedding),
but actually the parting reflects an internal alignment of clay grains
in the rock.
• Pencil cleavage forms because of the special characteristics of clay.
The strong shape anisotropy of clay
flakes creates a preferred orientation parallel to bedding when they
settle out of water and are compacted.
22. • This preferred orientation imparts the tendency
for clay-rich rocks to break on bedding planes
that is displayed by shale.
• Shale, mudstone, and slate are all names that
are used to describe clay-rich rocks; mudstone
is the general term for these rocks, whereas
shale and slate are foliated clay-rich rocks.
23. Slaty Cleavage
• Pencil cleavage may be considered a snapshot of an early
stage in the process by which slaty cleavage develops.
• This type of cleavage is best shown in fine grain rocks such
as mudstone that have been deformed under very low grade
metamorphic conditions.
• As shortening perpendicular to cleavage planes
accumulates, clay throughout the rock develops a preferred
orientation at an angle to the original sedimentary fabric and
this orientation dominates over the primary fabric (Figure
11.9c).
24. • Slaty cleavage is defined by
strong dimensionally preferred
orientation of phyllosilicates
in a very clay-rich rock, and
the resulting
rock, which is considered to
be a low-grade metamorphic
rock, is called a slate.
25. • Slaty cleavage tends to be smooth and planar.
This characteristic, coupled with the
penetrative nature of slaty cleavage, means
that slates can be split into thin sheets, which
made them popular roofing materials in the
nineteenth century and early parts of the
twentieth century.
26. Phyllitic Cleavage and Schistosity
• When metamorphic conditions reach the lower greenschist facies,
the clay and illite in a pelitic rock react to form white mica and
chlorite. If reaction occurs in an anisotropic stress field, these
phyllosilicates grow with a strong preferred orientation. Rock that is
composed of strongly aligned fine-grained white mica and/or
chlorite is called phyllite and the foliation that it contains is called
phyllitic cleavage.
• The mineralogy and fabric of phyllites give the rock a distinctive
silky luster. Phyllitic cleavage is intermediate between slaty
cleavage and schistosity.
27. Schistosity
• When metamorphic conditions get into the middle
greenschist facies, the minerals in a pelitic lithology react to
form coarser-grained mica and other minerals.
• When these reactions again take place in an anisotropic
stress field, the mica has a strong preferred orientation.
• The resulting rock is a schist, and the foliation it displays is
called schistosity.
• In schist that contains porphyroclasts (relict large crystals)
or porphyroblasts (newly grown large crystals), the
schistosity tends to be wavy, as the micas curve around the
large crystals.
28.
29. Crenulation Cleavage
• Crenulation cleavage is caused as the name suggests by small scale
folding (crenulation) of very thin layers or laminations within a
rock.
• If the axial surface of such crenulations are closely spaced and
parallel, they produce a marked foliation.
• This foliation is often enhanced by the selective recrystallization,
leading to concentration of certain constituents in layers.
• Thus micas, for example, may become concentrated in one set of
limbs of asymmetric crenulation or in both sets of limbs of
symmetric crenulation as a result of migration of the quartz and
calcite into the limbs or hinges.
• The combination of compositional banding and parallel orientation
of platy minerals provide planar weakness that can impart a strong
fissility to the rock.
30. • Cranulation cleavage is found in rocks which already posses
a strong cleavage or schistosity as a result of an earlier
deformation.
• Suitable rock lithology- very finely laminated shales.
• If the crenulation cleavage is very small, the resulting
cleavage becomes indistinguishable from other type of slaty
cleavage.
31. Solution cleavage
• A new compositional banding can arise through the
migration of certain constituents of the rock during
deformation, and for example, often accompanies
formation of crenulation cleavage.
• This phenomenon which is common in low grade
metamorphosed rock, is caused by the process of
pressure solution and the resulting cleavage is termed
as the solution cleavage.
• The solution and accompanying deposition appears to
be part of diffusion process which takes place by means
of grain boundary fluid phase.
32. Gneissosity
• A parallel banding produced by alternating
layers of different composition is an important
feature of the metamorphic rock.
• Gneisses are coarse grained metamorphic
rocks typically quatzo-feldspathic in
composition.
Editor's Notes
1“L” stands for “lineation”; “S” stands for “surface” in English, “schistosité” in French, or “Schieferung” in German.