This document discusses the concept of isostasy, which refers to the equilibrium between the continental and oceanic crust due to gravitational forces. It was first defined in 1889 by American geologist Clarence Dutton. The main points are that the continental crust must be composed of lighter materials than the ocean floor to remain in equilibrium. Also, wherever the continental crust is thinner under the oceans, it extends below the ocean floor to maintain equilibrium. Early evidence for isostasy came from Pierre Bouguer's 1735 expedition to the Andes mountains, where he observed smaller than expected gravitational attraction that indicated compensation of the mountains' mass.
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.
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. Fabrics can be primary, forming during rock formation processes, or secondary and resulting from deformation. Foliation refers specifically to planar fabric and can develop through processes like cleavage, schistosity, and mylonitic foliation under increasing metamorphic conditions and deformation. Lineations describe linear fabric elements oriented in rocks, such as intersection lineations between planar features or mineral lineations showing preferred mineral alignments. Together, foliations and lineations define the tectonite class of a rock.
A great landmass which was thought to be in the geological past, splitting into fragments drifting apart and again colliding into one another is called a supercontinent.1. VAALBARA -First ever made continent was Vaalbara which was 3.6 billion years old, it was named after kaapvaal and Pilbara which were the most ancient cratons present on that land mass. Kaapvaal is in Africa and Pilbara is in western Australia.2. UR- A supercontinent which was 3000 m.y.a and it was smaller than modern day Australia.3. KENORLAND- 2700 m.y.a famous events were HURONIAN GLACIATION. Also known as SNOWBALL EARTH.Responsible for formation of phytoplanktons.and VREDEFORT impact.4. COLUMBIA- Also called as NUNA . Period between Snowball Earth and subsequent Oxidation is called as THE BARREN BILLION.5. RODINIA- 1130 m.y.a.SECOND SNOWBALL EARTH.Also known as NEOPROTEROZOIC GLACIATION.6. PANNOTIA- 750 m.y.aThe formation of Pannotia was associated with the breakup of Rodinia into Proto- Gondwana and Proto-Laurasia. Two oceans were PANTHALSSA and Pan-African Ocean.7. PANGEA- One of the Youngest Supercontinent of all time , there are plenty of evidences of this Supercontinent. Like marine fossils from TETHYS OCEAN can be observed in Himalayas.
This document discusses various types of metamorphic reactions including solid-solid net transfer reactions, dehydration reactions, and decarbonation reactions. It also covers topics like the Clausius-Clapeyron equation, the effect of fluid pressure on reaction equilibria, and energy-temperature diagrams. The last few sections explain the rules of Schreinemakers for constructing stability diagrams and provide examples of applying these rules to 2-component mineral systems.
Ophiolites represent fragments of oceanic crust and upper mantle that have been uplifted and emplaced on continental margins. They consist of five distinct layers: sediment, pillow basalt, sheeted dikes, gabbro, and peridotite. Ophiolites provide evidence for seafloor spreading and plate tectonics. While similar in composition, ophiolites differ from oceanic crust in thickness, age, density, and how they are preserved on land rather than under water.
A sedimentary facies is a body of rock or sediment that is characterized by particular attributes that distinguish it from adjacent rock bodies. These attributes include lithology, color, texture, sedimentary structures, mineral/fossil content, and bed geometry. Together these attributes provide clues about the depositional environment. Different facies reflect different environments, such as beach/shallow marine facies indicating sandstone and offshore marine facies indicating shale. Facies analysis studies these attributes to interpret depositional environments and geological history at various scales.
This document discusses the concept of isostasy, which refers to the equilibrium between the continental and oceanic crust due to gravitational forces. It was first defined in 1889 by American geologist Clarence Dutton. The main points are that the continental crust must be composed of lighter materials than the ocean floor to remain in equilibrium. Also, wherever the continental crust is thinner under the oceans, it extends below the ocean floor to maintain equilibrium. Early evidence for isostasy came from Pierre Bouguer's 1735 expedition to the Andes mountains, where he observed smaller than expected gravitational attraction that indicated compensation of the mountains' mass.
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.
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. Fabrics can be primary, forming during rock formation processes, or secondary and resulting from deformation. Foliation refers specifically to planar fabric and can develop through processes like cleavage, schistosity, and mylonitic foliation under increasing metamorphic conditions and deformation. Lineations describe linear fabric elements oriented in rocks, such as intersection lineations between planar features or mineral lineations showing preferred mineral alignments. Together, foliations and lineations define the tectonite class of a rock.
A great landmass which was thought to be in the geological past, splitting into fragments drifting apart and again colliding into one another is called a supercontinent.1. VAALBARA -First ever made continent was Vaalbara which was 3.6 billion years old, it was named after kaapvaal and Pilbara which were the most ancient cratons present on that land mass. Kaapvaal is in Africa and Pilbara is in western Australia.2. UR- A supercontinent which was 3000 m.y.a and it was smaller than modern day Australia.3. KENORLAND- 2700 m.y.a famous events were HURONIAN GLACIATION. Also known as SNOWBALL EARTH.Responsible for formation of phytoplanktons.and VREDEFORT impact.4. COLUMBIA- Also called as NUNA . Period between Snowball Earth and subsequent Oxidation is called as THE BARREN BILLION.5. RODINIA- 1130 m.y.a.SECOND SNOWBALL EARTH.Also known as NEOPROTEROZOIC GLACIATION.6. PANNOTIA- 750 m.y.aThe formation of Pannotia was associated with the breakup of Rodinia into Proto- Gondwana and Proto-Laurasia. Two oceans were PANTHALSSA and Pan-African Ocean.7. PANGEA- One of the Youngest Supercontinent of all time , there are plenty of evidences of this Supercontinent. Like marine fossils from TETHYS OCEAN can be observed in Himalayas.
This document discusses various types of metamorphic reactions including solid-solid net transfer reactions, dehydration reactions, and decarbonation reactions. It also covers topics like the Clausius-Clapeyron equation, the effect of fluid pressure on reaction equilibria, and energy-temperature diagrams. The last few sections explain the rules of Schreinemakers for constructing stability diagrams and provide examples of applying these rules to 2-component mineral systems.
Ophiolites represent fragments of oceanic crust and upper mantle that have been uplifted and emplaced on continental margins. They consist of five distinct layers: sediment, pillow basalt, sheeted dikes, gabbro, and peridotite. Ophiolites provide evidence for seafloor spreading and plate tectonics. While similar in composition, ophiolites differ from oceanic crust in thickness, age, density, and how they are preserved on land rather than under water.
A sedimentary facies is a body of rock or sediment that is characterized by particular attributes that distinguish it from adjacent rock bodies. These attributes include lithology, color, texture, sedimentary structures, mineral/fossil content, and bed geometry. Together these attributes provide clues about the depositional environment. Different facies reflect different environments, such as beach/shallow marine facies indicating sandstone and offshore marine facies indicating shale. Facies analysis studies these attributes to interpret depositional environments and geological history at various scales.
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.
This document summarizes a seminar on applications of vapor geochemistry. It discusses how gases emanate from geological phenomena like ore deposits, oil fields, and volcanoes. These gases can be studied in soils, waters, and the atmosphere. Specific applications discussed include exploration for sulfide deposits using CO2 anomalies, locating uranium deposits using radon anomalies, and forecasting earthquakes and volcanic eruptions by monitoring certain gases. The document also reviews techniques for vapor surveys and challenges in sampling and interpretation.
Origin and Abundance of elements in the Solar system and in the Earth and its...AkshayRaut51
Definition of Elements and atom
Origin of Universe
Theories of origin of Solar system and Earth
Chemical Composition of Planets
Chemical Composition of Earth
Chemical composition of Meteorites
Abundance of Elements
The document summarizes the Bowen reaction series, which was developed by Norman Bowen in the early 1900s to explain the order of crystallization of minerals from cooling magma. It describes both the continuous and discontinuous reaction series, with the continuous series involving solid solution minerals like feldspar that adjust composition through diffusion as temperature decreases. The discontinuous series involves minerals like olivine melting at specific temperatures as new minerals begin to crystallize in equilibrium with the cooling magma. The Bowen reaction series and principle help explain how different rock types form from magmas of varying compositions as they cool.
The document provides an overview of the geology of the Moon. It describes the Moon's composition, features like maria (dark plains formed from ancient lava flows), highlands, craters, rilles, domes, and lava tubes. The Moon lacks an atmosphere and plate tectonics. Its surface was shaped primarily by impacts and volcanism. Samples collected during the Apollo missions have provided insights into the Moon's differentiated interior and early magma ocean.
The document summarizes several classification schemes for sandstone, focusing on the ternary QFL scheme that divides sandstones based on their quartz, feldspar, and lithic fragment composition as determined through point counting of thin sections. The document also describes various sandstone compositions including quartz arenite, feldspathic arenite/wacke, lithic wacke, and others; and discusses framework grains, matrix, cement, porosity, and the influence of provenance on sandstone composition.
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.
Geodynamics studies mantle convection and plate tectonics to understand phenomena like seafloor spreading and mountain building. It provides fundamentals for how the solid Earth works as a heat engine. Early theorists like Wegener and Du Toit proposed continental drift to explain geological similarities between continents. In the 1960s, seafloor mapping and studies of magnetic pole positions in rocks supported plate tectonics, where convection in the mantle drives the motion of rigid tectonic plates. This theory was accepted when it provided a unifying framework and mechanism to explain observations of geology and geophysics.
Diagenesis is the process by which changes occur in sediment after it is deposited until the onset of metamorphism. During diagenesis, loose sediments are transformed into a solid rock through compaction, recrystallization, dissolution, replacement, cementation, and other processes. These diagenetic processes are important as they can significantly modify the composition and properties of the original sediment and even destroy sedimentary structures in rare cases.
The document summarizes the main layers and divisions of the Earth based on their chemical composition and physical properties. It is divided into three main layers:
1. The crust, which is the outermost solid layer and varies in thickness between continental and oceanic crust.
2. The mantle, which makes up over 80% of the Earth's volume and can be divided into the upper, lower, and D'' transition zones based on seismic properties.
3. The core, which is divided into a solid inner core and liquid outer core, and makes up about 30% of the Earth's mass.
Galassie, sfera celeste, costellazioni, luce, spettroscopia e leggi del corpo...Roberto Gregoratti
Powerpoint su sfera celeste sistema solare, galassie, costellazioni, luce, spettri, coordinate astronomiche, spettroscopia, spettri e leggi del corpo nero
This document summarizes the key characteristics and types of magma. It defines magma as a mixture of molten or semi-molten rock found beneath the Earth's surface. Magma forms through mechanisms like decompression melting when hot mantle material rises and melts lower pressure rock, or flux melting when water or carbon dioxide lowers the melting temperature of mantle rock. Magma can be classified based on its chemical composition into basaltic, andesitic, or rhyolitic types depending on silicon and iron/magnesium content, and each type has distinct physical properties like temperature, viscosity, and gas content that determine explosiveness. Magma is also differentiated based on how it formed, such as primitive, primary, parental
Geochemistry studies the chemical composition and properties of rocks. It examines the distribution and behavior of chemical elements within the Earth's crust. The periodic table evolved over time as scientists like Döbereiner grouped elements into triads based on their atomic weights, and Mendeleev arranged the known elements into the first periodic table based on recurring trends in their properties. This allowed prediction of properties of yet-to-be discovered elements and established atomic weight as the basis for organization until Moseley showed atomic number provided an even more systematic relationship.
This is my presentation on the tectonic control of sediments.
It includes the effects of tectonics either direct or indirect on sediments and sedimentation.
Sedimentation along various plate boundaries.
Few examples as evidence from Pakistan (the Siwalik Group) and Argentina (Fiambala Basin)
The document summarizes the Cambrian deposits found in extra-peninsular India. It discusses the Cambrian system, which covers the period between 570-500 million years ago. Three major locations of Cambrian deposits in India are highlighted: the Salt Range in northwest Punjab, the Spiti Valley, and Kashmir. The Salt Range contains a thick series of marine fossiliferous rocks from the Cambrian period, including salt pseudomorph shales, magnesium sandstones, Neobolus beds, and purple sandstones. Trilobites, brachiopods, and hyoliths found in the strata indicate a Lower Cambrian age.
There are three basic types of meteorites: stony, iron, and stony-iron. Stony meteorites are the most common type, making up 90% of meteorite falls. The value of a meteorite depends on its chemical composition and abundance - rare meteorites from Mars or the Moon can be worth $2,500-$3,000 per gram. Meteorite hunters search known strewn fields using metal detectors and magnets to locate scattered fragments, sometimes following eyewitness accounts of meteorite falls.
This document discusses various mechanisms that can cause variation in igneous rocks, including magmatic differentiation, assimilation, and magma mixing. It defines primary and parental magmas and explains that over 700 types of igneous rocks exist despite only a few primary magma types. The key mechanisms of magmatic differentiation discussed are fractional crystallization, liquid immiscibility, vapor transport, and thermal diffusion. Assimilation and magma mixing are also explained as additional processes that can change a magma's composition and result in diverse rock types. Specific examples like carbonatites and unusual rock compositions provide evidence of these differentiation and mixing processes.
The document outlines specific learning outcomes for a lesson on rock types. At the end of the lesson, students will be able to: identify and describe the three basic rock types; describe how each rock type forms and define their environments of formation; describe how rocks are transformed through the rock cycle; and identify and describe different geologic processes in the rock cycle.
Deriva dei continenti e la tettonica a placchePaolo Balocchi
deriva dei continenti, tettonica a placche, margini di placca, divergenti, convergenti, trasformi, tipi di collisione, oceano-oceano, continente-oceano, continente-continente, motore della tettonica, celle convettive, trascinamento, spinta, flusso astenosferico
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.
This document summarizes a seminar on applications of vapor geochemistry. It discusses how gases emanate from geological phenomena like ore deposits, oil fields, and volcanoes. These gases can be studied in soils, waters, and the atmosphere. Specific applications discussed include exploration for sulfide deposits using CO2 anomalies, locating uranium deposits using radon anomalies, and forecasting earthquakes and volcanic eruptions by monitoring certain gases. The document also reviews techniques for vapor surveys and challenges in sampling and interpretation.
Origin and Abundance of elements in the Solar system and in the Earth and its...AkshayRaut51
Definition of Elements and atom
Origin of Universe
Theories of origin of Solar system and Earth
Chemical Composition of Planets
Chemical Composition of Earth
Chemical composition of Meteorites
Abundance of Elements
The document summarizes the Bowen reaction series, which was developed by Norman Bowen in the early 1900s to explain the order of crystallization of minerals from cooling magma. It describes both the continuous and discontinuous reaction series, with the continuous series involving solid solution minerals like feldspar that adjust composition through diffusion as temperature decreases. The discontinuous series involves minerals like olivine melting at specific temperatures as new minerals begin to crystallize in equilibrium with the cooling magma. The Bowen reaction series and principle help explain how different rock types form from magmas of varying compositions as they cool.
The document provides an overview of the geology of the Moon. It describes the Moon's composition, features like maria (dark plains formed from ancient lava flows), highlands, craters, rilles, domes, and lava tubes. The Moon lacks an atmosphere and plate tectonics. Its surface was shaped primarily by impacts and volcanism. Samples collected during the Apollo missions have provided insights into the Moon's differentiated interior and early magma ocean.
The document summarizes several classification schemes for sandstone, focusing on the ternary QFL scheme that divides sandstones based on their quartz, feldspar, and lithic fragment composition as determined through point counting of thin sections. The document also describes various sandstone compositions including quartz arenite, feldspathic arenite/wacke, lithic wacke, and others; and discusses framework grains, matrix, cement, porosity, and the influence of provenance on sandstone composition.
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.
Geodynamics studies mantle convection and plate tectonics to understand phenomena like seafloor spreading and mountain building. It provides fundamentals for how the solid Earth works as a heat engine. Early theorists like Wegener and Du Toit proposed continental drift to explain geological similarities between continents. In the 1960s, seafloor mapping and studies of magnetic pole positions in rocks supported plate tectonics, where convection in the mantle drives the motion of rigid tectonic plates. This theory was accepted when it provided a unifying framework and mechanism to explain observations of geology and geophysics.
Diagenesis is the process by which changes occur in sediment after it is deposited until the onset of metamorphism. During diagenesis, loose sediments are transformed into a solid rock through compaction, recrystallization, dissolution, replacement, cementation, and other processes. These diagenetic processes are important as they can significantly modify the composition and properties of the original sediment and even destroy sedimentary structures in rare cases.
The document summarizes the main layers and divisions of the Earth based on their chemical composition and physical properties. It is divided into three main layers:
1. The crust, which is the outermost solid layer and varies in thickness between continental and oceanic crust.
2. The mantle, which makes up over 80% of the Earth's volume and can be divided into the upper, lower, and D'' transition zones based on seismic properties.
3. The core, which is divided into a solid inner core and liquid outer core, and makes up about 30% of the Earth's mass.
Galassie, sfera celeste, costellazioni, luce, spettroscopia e leggi del corpo...Roberto Gregoratti
Powerpoint su sfera celeste sistema solare, galassie, costellazioni, luce, spettri, coordinate astronomiche, spettroscopia, spettri e leggi del corpo nero
This document summarizes the key characteristics and types of magma. It defines magma as a mixture of molten or semi-molten rock found beneath the Earth's surface. Magma forms through mechanisms like decompression melting when hot mantle material rises and melts lower pressure rock, or flux melting when water or carbon dioxide lowers the melting temperature of mantle rock. Magma can be classified based on its chemical composition into basaltic, andesitic, or rhyolitic types depending on silicon and iron/magnesium content, and each type has distinct physical properties like temperature, viscosity, and gas content that determine explosiveness. Magma is also differentiated based on how it formed, such as primitive, primary, parental
Geochemistry studies the chemical composition and properties of rocks. It examines the distribution and behavior of chemical elements within the Earth's crust. The periodic table evolved over time as scientists like Döbereiner grouped elements into triads based on their atomic weights, and Mendeleev arranged the known elements into the first periodic table based on recurring trends in their properties. This allowed prediction of properties of yet-to-be discovered elements and established atomic weight as the basis for organization until Moseley showed atomic number provided an even more systematic relationship.
This is my presentation on the tectonic control of sediments.
It includes the effects of tectonics either direct or indirect on sediments and sedimentation.
Sedimentation along various plate boundaries.
Few examples as evidence from Pakistan (the Siwalik Group) and Argentina (Fiambala Basin)
The document summarizes the Cambrian deposits found in extra-peninsular India. It discusses the Cambrian system, which covers the period between 570-500 million years ago. Three major locations of Cambrian deposits in India are highlighted: the Salt Range in northwest Punjab, the Spiti Valley, and Kashmir. The Salt Range contains a thick series of marine fossiliferous rocks from the Cambrian period, including salt pseudomorph shales, magnesium sandstones, Neobolus beds, and purple sandstones. Trilobites, brachiopods, and hyoliths found in the strata indicate a Lower Cambrian age.
There are three basic types of meteorites: stony, iron, and stony-iron. Stony meteorites are the most common type, making up 90% of meteorite falls. The value of a meteorite depends on its chemical composition and abundance - rare meteorites from Mars or the Moon can be worth $2,500-$3,000 per gram. Meteorite hunters search known strewn fields using metal detectors and magnets to locate scattered fragments, sometimes following eyewitness accounts of meteorite falls.
This document discusses various mechanisms that can cause variation in igneous rocks, including magmatic differentiation, assimilation, and magma mixing. It defines primary and parental magmas and explains that over 700 types of igneous rocks exist despite only a few primary magma types. The key mechanisms of magmatic differentiation discussed are fractional crystallization, liquid immiscibility, vapor transport, and thermal diffusion. Assimilation and magma mixing are also explained as additional processes that can change a magma's composition and result in diverse rock types. Specific examples like carbonatites and unusual rock compositions provide evidence of these differentiation and mixing processes.
The document outlines specific learning outcomes for a lesson on rock types. At the end of the lesson, students will be able to: identify and describe the three basic rock types; describe how each rock type forms and define their environments of formation; describe how rocks are transformed through the rock cycle; and identify and describe different geologic processes in the rock cycle.
Deriva dei continenti e la tettonica a placchePaolo Balocchi
deriva dei continenti, tettonica a placche, margini di placca, divergenti, convergenti, trasformi, tipi di collisione, oceano-oceano, continente-oceano, continente-continente, motore della tettonica, celle convettive, trascinamento, spinta, flusso astenosferico
Deriva dei continenti / Tettonica delle placcheiperclasse
DERIVA DEI CONTINENTI in italiano per scuola media
Continental drift in Italian
Presentazione breve e senza pretese, a supporto di una spiegazione di geografia
In questo percorso interattivo di storia per la classe terza di scuola primaria, non troverete testi da studiare, ma un repertorio di tematiche con proposte di materiali, risorse e attività da realizzare. Lo scopo è quello di fornire all’insegnante uno strumento da cui partire per progettare un percorso didattico che permetta ai bambini la co-costruzione di conoscenza significativa e rilevante, caratterizzata dalla complessità, reticolo dinamico, struttura in cui ogni parte è interconnessa con le altre e dalla cui connessione deriva la struttura dell'intera rete che può essere esplorata e compresa partendo da un punto qualsiasi, permettendo l’approfondimento dei concetti fondanti
della storia.
"a che tante facelle" dott. Davide Maino Astrofisico Milanogiuseppe peranzoni
Corso di aggiornamento presso il Michelangelo Buonarroti di Trento - 12 febraio 2007 - Direzione del corso didattica e innovazione scolastica (DIESSE Trento)
Progetto Interdisciplinare a scopo educativo-ambientale,
CLASSE 2^ B Scuola Secondaria di I grado, IC POLO 2 Galatina (Le), Plesso di Noha, A.S. 2013-14.
A.S. 2013-14
1. LA DERIVA DEI CONTINENTILA DERIVA DEI CONTINENTI
E LAE LA
TETTONICA DELLE PLACCHETETTONICA DELLE PLACCHE
Classe III
Scuola Secondaria di Primo Grado
PAS A059 a.a. 2014/15 corsista A. Anania
2.
PREREQUISITIPREREQUISITI:
conoscere i concetti di pressione, temperatura, calore e
densità;
conoscere la struttura della materia e i cambiamenti di
stato;
conoscere la struttura interna della Terra;
i terremoti;
i vulcani;
le faglie.
Programmazione unità didattica
3. OBIETTIVI COGNITIVIOBIETTIVI COGNITIVI (conoscenze): conoscere il modello della
tettonica delle placche; sapere il numero e la natura delle
placche in cui è suddivisa la litosfera; conoscere il “motore”
delle placche; conoscere i margini delle placche e le loro
interazioni
COMPETENZE:COMPETENZE: l’alunno sa raccogliere, tabulare ed elaborare
semplici dati sperimentali; utilizza correttamente materiali ed
attrezzature; ha l’attitudine ad un lavoro sistematico; sa
descrivere in maniera scientifica le osservazioni sperimentali;
sa lavorare in gruppo
Programmazione unità didattica
4.
Programmazione unità didattica
METODOLOGIAMETODOLOGIA: lezione frontale partecipata di tipo laboratoriale
STRUMENTISTRUMENTI: materiale multimediale; LIM; rete internet per l’utilizzo di
Google Earth
VERIFICHEVERIFICHE: prova scritta strutturata e semistrutturata (quesiti a risposta
multipla, V/F, a risposta aperta); colloquio orale
VALUTAZIONEVALUTAZIONE: formativa in itinere per valutare impegno e
comportamenti degli alunni; sommativa per valutare conoscenze, abilità e
competenze.
19. Che cosa provoca il movimento delle placche?Che cosa provoca il movimento delle placche?
Il motore degli
spostamenti delle
placche oceaniche e
continentali è
costituito dai motimoti
convettiviconvettivi del
mantello
20. Nel mantello masse di rocce
profonde divenute più calde del
materiale circostante tendono a
risalire verso la crosta con
movimenti lentissimi. Si comportano
in modo simile all'acqua che bolle in
una pentola posta sul fuoco.
Il movimento delle placcheIl movimento delle placche
I materiali più profondi del
mantello si riscaldano, diventano
più leggeri e salgono (correnti
ascendenti), prendendo il
posto dei materiali più freddi e
densi, che, al contrario,
scendono (correnti
discendenti).
21. In questo caso la notevole
differenza di densità tra le
due placche fa sì che sia la
placca oceanica ad essere
subdotta.
Crosta oceanica vs crosta continentaleCrosta oceanica vs crosta continentale
Sul continente si forma un
arco magmatico.
Un esempio è la fossa del Cile
con la Cordigliera delle Ande
22. Anche se in questo caso non
esiste sostanziale differenza
di densità di materiali, una
delle due placche si infossa
sotto l’altra, con un
fenomeno chiamato
subduzionesubduzione.
Crosta oceanica vs crosta oceanicaCrosta oceanica vs crosta oceanica
si ha la formazione di una fossafossa e di un arcoarco
vulcanicovulcanico insulareinsulare; in questo modo si sono
formate le fosse delle Filippine e delle Marianne
e si è formato l’arcipelago giapponese
23. La sostanziale
corrispondenza di densità tra
le due placche interessate al
fenomeno fa sì che non ci sia
subduzione. I margini delle
zolle si sovrappongono e si
accavallano l’uno all’altro,
dando così origine a catene
montuose interne ai
continenti: l’OROGENESI
Crosta continentale vs crostaCrosta continentale vs crosta
continentalecontinentale
Ad esempio la catena alpino-
himalayana
24.
25.
26. In alcuni casi il movimento reciproco delle zolle non
vede né subduzione né accavallamento, ma
scivolamento, scorrimento laterale, senza che i due
blocchi si avvicinino o si allontanino.
Margini trasformiMargini trasformi
Nella foto possiamo
vedere la faglia di San
Andreas in California