Igneous petrology
Encyclopedia
Igneous petrology is the study of igneous rock
, those that are formed from magma
. Igneous petrology is as a branch of geology
closely related to volcanology
, tectonophysics
and petrology
in general. The modern study of igneous rocks is done using several techniques some of the developed in the areas of chemistry
and physics
or from other earth sciences. Petrography
, crystallography
, and isotopic
studies are common methods used in igneous petrology.
. These microscopes have polarizing plates, filters, and a conoscopic lens that allow the user to measure a large number of crystallographic properties. Another method for determining mineralogy is to use X-ray diffraction, in which a powdered sample is bombarded by X-rays, and the resultant spectrum of crystallographic orientations is compared to a set of standards. One of the most precise ways of determining chemical composition is by the use of an electron microprobe
, in which tiny spots of materials are sampled. Electron microprobe analyses can detect both bulk composition and trace element
composition.
trapped in a rock are compared to the amount of 40K
in the rock to calculate the amount of time 40K must have been decaying in the solid rock to produce all 40Ar that would have otherwise not have been present there.
is based on the natural decay
of 87Rb
to 87Sr
and the different behaviour of these elements during fractional crystallization
of magma. Both Sr and Rb are found in most magmas, however as fractional crystallization occurs Sr will tend to be concentrated in plagioclase
crystals while Rb will remain in the melt for longer time. 87Rb decays in magma and elsewhere so that every 1.42×1011 years half of the amount has been converted into 87Sr. Knowing the decay constant and the amount of 87Rb and 87Sr in a rock it is possible to calculate the time that the 87Rb must have needed before the rock reached closure temperature
to produce all 87Sr, yet considering that there was an initial 87Sr amount no produced by 87Rb in the magmatic body. Initial values of 87Sr, when the magma stated fractional crystallization, might be estimated by knowing the amounts of 87Rb and 87Sr of two igneous rocks produced at different times by the same magmatic body.
es stratigraphy
may be useful to gain knowledge of the relative age
of volcanic rocks. Tephrochronology
is the most common application of stratigraphic dating on volcanic rocks. Volcanic eruptions might also be dated through radiocarbon dating
of organic remnants buried on lava or tephra
.
the mineral
clinopyroxene is used for temperature
and pressure
calculations of the magma
that produced igneous rock
containing this mineral. Clinopyroxene thermobarometry is one of several geothermobarometers
. Two things makes this method especially useful; first, clinopyroxene is a common phenocryst
in igneous rocks easy to identify, second, the crystallization
of the jadeite
component of clinopyroxene implies a growth in molar volume
being thus a good indicator of pressure
.
s of worldwide circulation such as Science
and Nature
. Study material, overviews of certain topics and older works are often found as books. Many works before the plate tectonics
paradigm shift
in the 1960s and 1970s contains inaccurate information regarding the origin of magmas.
Igneous rock
Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...
, those that are formed from magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
. Igneous petrology is as a branch of geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
closely related to volcanology
Volcanology
Volcanology is the study of volcanoes, lava, magma, and related geological, geophysical and geochemical phenomena. The term volcanology is derived from the Latin word vulcan. Vulcan was the ancient Roman god of fire....
, tectonophysics
Tectonophysics
Tectonophysics, a branch of geophysics, is the study of the physical processes that underlie tectonic deformation. The field encompasses the spatial patterns of stress, strain, and differing rheologies in the lithosphere and asthenosphere of the Earth; and the relationships between these patterns...
and petrology
Petrology
Petrology is the branch of geology that studies rocks, and the conditions in which rocks form....
in general. The modern study of igneous rocks is done using several techniques some of the developed in the areas of chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
and physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
or from other earth sciences. Petrography
Petrography
Petrography is a branch of petrology that focuses on detailed descriptions of rocks. Someone who studies petrography is called a petrographer. The mineral content and the textural relationships within the rock are described in detail. Petrographic descriptions start with the field notes at the...
, crystallography
Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
, and isotopic
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
studies are common methods used in igneous petrology.
Determination of chemical composition
The composition of igneous rocks and minerals can be determined via a variety of methods of varying ease, cost, and complexity. The simplest method is observation of hand samples with the naked eye and/or with a hand lens. This can be used to gauge the general mineralogical composition of the rock, which gives an insight into the composition. A more precise but still relatively inexpensive way to identify minerals (and thereby the bulk chemical composition of the rock) with a petrographic microscopePetrographic microscope
A petrographic microscope is a type of optical microscope used in petrology and optical mineralogy to identify rocks and minerals in thin sections. The microscope is used in optical mineralogy and petrography, a branch of petrology which focuses on detailed descriptions of rocks...
. These microscopes have polarizing plates, filters, and a conoscopic lens that allow the user to measure a large number of crystallographic properties. Another method for determining mineralogy is to use X-ray diffraction, in which a powdered sample is bombarded by X-rays, and the resultant spectrum of crystallographic orientations is compared to a set of standards. One of the most precise ways of determining chemical composition is by the use of an electron microprobe
Electron microprobe
An electron microprobe , also known as an electron probe microanalyzer or electron micro probe analyzer , is an analytical tool used to non-destructively determine the chemical composition of small volumes of solid materials...
, in which tiny spots of materials are sampled. Electron microprobe analyses can detect both bulk composition and trace element
Trace element
In analytical chemistry, a trace element is an element in a sample that has an average concentration of less than 100 parts per million measured in atomic count, or less than 100 micrograms per gram....
composition.
Dating methods
The dating of igneous rocks determines when magma solified into rock. Radiogenic isotopes as frequently used to determine the age of igneous rocks.Potassium-argon dating
In this dating method the amount of 40ArIsotopes of argon
Argon has 24 known isotopes, from 30Ar to 53Ar and 1 isomer , three of which are stable, 36Ar, 38Ar, and 40Ar. On Earth, 40Ar makes up 99.6% of natural argon. The longest-lived radioactive isotopes are 39Ar with a half-life of 269 years, 42Ar with a half-life of 32.9 years, and 37Ar with a...
trapped in a rock are compared to the amount of 40K
Isotopes of potassium
Potassium has 25 known isotopes from 32K to 56K. Three isotopes occur naturally: stable 39K and 41K , and the long-lived radioisotope 40K . The standard atomic mass is 39.0983 u. Naturally occurring 40K decays to stable 40Ar by electron capture or positron emission...
in the rock to calculate the amount of time 40K must have been decaying in the solid rock to produce all 40Ar that would have otherwise not have been present there.
Rubidium-strontium dating
The rubidium-strontium datingRubidium-strontium dating
The rubidium-strontium dating method is a radiometric dating technique that geologists use to determine the age of rocks.Development of this process was aided by Fritz Strassmann, who later went on to discover nuclear fission with Otto Hahn and Lise Meitner....
is based on the natural decay
Radioactive decay
Radioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
of 87Rb
Isotopes of rubidium
Rubidium has 32 isotopes, with naturally occurring rubidium being composed of just two isotopes; 85Rb and the radioactive 87Rb . Normal mixes of rubidium are radioactive enough to fog photographic film in approximately 30 to 60 days. Standard atomic mass is 85.4678 u.87Rb has a half-life of...
to 87Sr
Isotopes of strontium
The alkaline earth metal strontium has four stable, naturally occurring isotopes:84Sr , 86Sr , 87Sr and 88Sr . It has a standard atomic mass of 87.62 u....
and the different behaviour of these elements during fractional crystallization
Fractional crystallization (geology)
Fractional crystallization is one of the most important geochemical and physical processes operating within the Earth's crust and mantle. Fractional crystallization is the removal and segregation from a melt of mineral precipitates; except in special cases, removal of the crystals changes the...
of magma. Both Sr and Rb are found in most magmas, however as fractional crystallization occurs Sr will tend to be concentrated in plagioclase
Plagioclase
Plagioclase is an important series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar series...
crystals while Rb will remain in the melt for longer time. 87Rb decays in magma and elsewhere so that every 1.42×1011 years half of the amount has been converted into 87Sr. Knowing the decay constant and the amount of 87Rb and 87Sr in a rock it is possible to calculate the time that the 87Rb must have needed before the rock reached closure temperature
Closure temperature
In radiometric dating, closure temperature or blocking temperature refers to the temperature of a system, such as a mineral, at the time given by its radiometric date. In physical terms, the closure temperature at which a system has cooled so that there is no longer any exchange of parent or...
to produce all 87Sr, yet considering that there was an initial 87Sr amount no produced by 87Rb in the magmatic body. Initial values of 87Sr, when the magma stated fractional crystallization, might be estimated by knowing the amounts of 87Rb and 87Sr of two igneous rocks produced at different times by the same magmatic body.
Other methods
In the case of volcanoVolcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
es stratigraphy
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
may be useful to gain knowledge of the relative age
Relative dating
Relative dating is the science determining the relative order of past events, without necessarily determining their absolute age.In geology rock or superficial deposits, fossils and lithologies can be used to correlate one stratigraphic column with another...
of volcanic rocks. Tephrochronology
Tephrochronology
250px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at the height of the [[volcanologists]] hands is [[rhyolitic]] [[tephra]] from [[Hekla]]....
is the most common application of stratigraphic dating on volcanic rocks. Volcanic eruptions might also be dated through radiocarbon dating
Radiocarbon dating
Radiocarbon dating is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. Raw, i.e. uncalibrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" ,...
of organic remnants buried on lava or tephra
Tephra
200px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at center of the photo is [[rhyolitic]] tephra from [[Hekla]]....
.
Thermobarometry methods
In petrologyPetrology
Petrology is the branch of geology that studies rocks, and the conditions in which rocks form....
the mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
clinopyroxene is used for temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
and pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
calculations of the magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
that produced igneous rock
Igneous rock
Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...
containing this mineral. Clinopyroxene thermobarometry is one of several geothermobarometers
Geothermobarometry
Geothermobarometry is the science of measuring the previous pressure and temperature history of a metamorphic or intrusive igneous rocks. Geothermobarometry is a combination of geobarometry, where a pressure of mineral formation is resolved, and geothermometry where a temperature of formation is...
. Two things makes this method especially useful; first, clinopyroxene is a common phenocryst
Phenocryst
thumb|right|300px|[[Granite]]s often have large [[feldspar|feldspatic]] phenocrysts. This granite, from the [[Switzerland|Swiss]] side of the [[Mont Blanc]] massif, has large white [[plagioclase]] phenocrysts, [[triclinic]] [[mineral]]s that give [[trapezium|trapezoid]] shapes when cut through)...
in igneous rocks easy to identify, second, the crystallization
Fractional crystallization (geology)
Fractional crystallization is one of the most important geochemical and physical processes operating within the Earth's crust and mantle. Fractional crystallization is the removal and segregation from a melt of mineral precipitates; except in special cases, removal of the crystals changes the...
of the jadeite
Jadeite
Jadeite is a pyroxene mineral with composition NaAlSi2O6. It is monoclinic. It has a Mohs hardness of about 6.5 to 7.0 depending on the composition. The mineral is dense, with a specific gravity of about 3.4. Jadeite forms solid solutions with other pyroxene endmembers such as augite and diopside ,...
component of clinopyroxene implies a growth in molar volume
Molar volume
The molar volume, symbol Vm, is the volume occupied by one mole of a substance at a given temperature and pressure. It is equal to the molar mass divided by the mass density...
being thus a good indicator of pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
.
Publications
Most contemporary ground breaking in igneous petrology is published on prestigious British and American scientific journalScientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. There are thousands of scientific journals in publication, and many more have been published at various points in the past...
s of worldwide circulation such as Science
Science (magazine)
Science was a general science magazine published by the American Association for the Advancement of Science . It was intended to "bridge the distance between science and citizen", aimed at a technically literate audience who may not work professionally in the sciences...
and Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
. Study material, overviews of certain topics and older works are often found as books. Many works before the plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
paradigm shift
Paradigm shift
A Paradigm shift is, according to Thomas Kuhn in his influential book The Structure of Scientific Revolutions , a change in the basic assumptions, or paradigms, within the ruling theory of science...
in the 1960s and 1970s contains inaccurate information regarding the origin of magmas.
| Name | Publisher | Scope |
|---|---|---|
| American Mineralogist American Mineralogist American Mineralogist is the peer-reviewed journal of the Mineralogical Society of America , a non-profit association. It publishes original scientific research in the general fields of mineralogy, crystallography, geochemistry, and petrology.... |
Mineralogical Society of America Mineralogical Society of America The Mineralogical Society of America is a scientific membership organization. MSA was founded in 1919 for the advancement of mineralogy, crystallography, geochemistry, and petrology, and promotion of their uses in other sciences, industry, and the arts... |
Mineralogy Mineralogy Mineralogy is the study of chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.-History:Early writing... , petrology Petrology Petrology is the branch of geology that studies rocks, and the conditions in which rocks form.... , crystallography Crystallography Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of... , geochemistry Geochemistry The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks, water, and soils, and the cycles of matter and energy that transport the Earth's chemical components in time and space, and... |
| Andean geology Andean Geology Andean Geology is a scientific journal published by Servicio Nacional de Geología y Minería, Chile's geology and mining agency. It contains articles that are published in the field of geology and related earth sciences, primarily on issues that are relevant to Chile and the Andes... |
SERNAGEOMIN | Geology Geology Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates... of the Andes Andes The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated... , Central America Central America Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent... , the Caribbean Caribbean The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north... and the Antarctic Peninsula Antarctic Peninsula The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands.... |
| Bulletin of Volcanology Bulletin of Volcanology The Bulletin of Volcanology is the official journal of the International Association of Volcanology and Chemistry of the Earth's Interior published by Springer Science+Business Media... |
Springer Springer Science+Business Media - Selected publications :* Encyclopaedia of Mathematics* Ergebnisse der Mathematik und ihrer Grenzgebiete * Graduate Texts in Mathematics * Grothendieck's Séminaire de géométrie algébrique... |
Volcanology Volcanology Volcanology is the study of volcanoes, lava, magma, and related geological, geophysical and geochemical phenomena. The term volcanology is derived from the Latin word vulcan. Vulcan was the ancient Roman god of fire.... |
| Contributions to Mineralogy and Petrology Contributions to Mineralogy and Petrology Contributions to Mineralogy and Petrology is a peer-reviewed scientific journal published by Springer Science+Business Media since 1947. The journal accepts high quality research papers in the fields of igneous and metamorphic petrology, geochemistry and mineralogy.- Subjects covered :Topical... |
Springer Springer Science+Business Media - Selected publications :* Encyclopaedia of Mathematics* Ergebnisse der Mathematik und ihrer Grenzgebiete * Graduate Texts in Mathematics * Grothendieck's Séminaire de géométrie algébrique... |
Mineralogy Mineralogy Mineralogy is the study of chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.-History:Early writing... , petrology Petrology Petrology is the branch of geology that studies rocks, and the conditions in which rocks form.... |
| Journal of Petrology | Oxford University Press Oxford University Press Oxford University Press is the largest university press in the world. It is a department of the University of Oxford and is governed by a group of 15 academics appointed by the Vice-Chancellor known as the Delegates of the Press. They are headed by the Secretary to the Delegates, who serves as... |
Petrology Petrology Petrology is the branch of geology that studies rocks, and the conditions in which rocks form.... |
| Journal of Volcanology and Geothermal Research Journal of Volcanology and Geothermal Research Journal of Volcanology and Geothermal Research is a scientific journal that publishes recent research on the fields of volcanology and geothermal activity.- See also :* List of scientific journals... |
Elsevier Elsevier Elsevier is a publishing company which publishes medical and scientific literature. It is a part of the Reed Elsevier group. Based in Amsterdam, the company has operations in the United Kingdom, USA and elsewhere.... |
Volcanology Volcanology Volcanology is the study of volcanoes, lava, magma, and related geological, geophysical and geochemical phenomena. The term volcanology is derived from the Latin word vulcan. Vulcan was the ancient Roman god of fire.... , geothermal research |
Igneous petrologists
- James HuttonJames HuttonJames Hutton was a Scottish physician, geologist, naturalist, chemical manufacturer and experimental agriculturalist. He is considered the father of modern geology...
- Nicholas Demarest
- Pierre Louis Cordier
- Norman L. BowenNorman L. BowenNorman Levi Bowen was born in Kingston, Ontario, Canada June 21, 1887 and died on September 11, 1956. Bowen "revolutionized experimental petrology and our understanding of mineral crystallization...