Igneous rocks of the convergent margins tulane university. Intrusiveextrusive lightdark small grainlarge grain the bigger the grains, the slower it cooled. The book is divided into nine chapters and ancillary material. In practice, this means that the average dimension of the crystals is less than 1 millimeter. The prime example of this style of mineralization is the giant kidd creek deposit, where most mineralization occurred below the seafloor in permeable, fragmental felsic volcanic. A magma consists mostly of liquid rock matter, but may.
Each of these is introduced simplistically below, and then further explored in other pages of the site. Intrusive or plutonic igneous rocks wherein the magma crystallizes at depth in the earth magma is a mixture of liquid rock, crystals, and gas. View notes igneous from eens 1110 at tulane university. The aim of the book is to help students to develop appropriate descriptive and inter. An introduction to igneous and metamorphic petrology, john winter, prentice hall. By comparison of their characters with those of certain igneous rocks intercalated in the geological column, it can be shown that the latter are the lavas of. Igneous rocks igneous rocks form by cooling and crystallization of molten rock molten material residing below earths surface is known as magma, whereas the same material at the surface is called lava. When the magma reaches the earths surface and turns into lava, it cools and turns into igneous rock. Igneous rocks page 1 of 14 eens 1110 physical geology tulane university prof. Igneous rocks are the oldest type of rock and is a volcanic rock. This cheat sheet pack contains some practical advice on. This lecture is designed to give you a general overview of how igneous rocks are related to tectonic setting. Topics covered include criteria for the classification of igneous rocks, field identification of minerals present in hand sample, thin section examination and chemical analysis.
Teacher notes if your students have completed the plate tectonic units on volcanoes, they should be familiar with different volcanic environments. A wide variety of igneous rocks occur in the continental lithosphere, a reflection of its. The minerals that make up igneous rocks crystallize at a range of different temperatures. Large igneous provinces lips these are massive outpourings of.
Theres just a bewildering number of rocks to remember, minerals to be familiar with and textures to recognise. Lecture notes 3 igneous rocks glendale community college. A link within the document will lead you to a pdf file geared for printing this list. F767 2014 5521dc23 2012168 isbn 9781107027541 hdbacra k. Nelson magmas and igneous rocks magma and igneous rocks igneous rocks are formed by crystallization from a liquid, or magma. Dockery iii at 5 years old picking up stray rocks and collecting them in a bucket could have predicted his career as an acclaimed geologist. This grade includes quality of petrographic analyses, sem calculations, grammar and spelling, layout, clarity, readability, critical evaluation of your data in comparison to data in the literature, proper captions and labels for your images, graphs, and figures, etc. Magmas and igneous rocks, discusses the composition of ig neous rocks and the interrelationships of elemental variation. An igneous rock or a part of an igneous rock with a finegrained or aphanitic texture has crystals, but they are too small to recognized with the unaided eye. Dockery filled his childhood days exploring his jackson, mississippi, neighborhood with kids from his community. To simplify the discussion we are severely reducing the number of. The iugs mineralogical based classification and nomenclature scheme for phaneritic and aphanitic igneous rocks. Metamorphic rocks are former igneous, sedimentary or metamorphic rocks that have changed their texture and composition.
In the modern oceans, the mafic association is found in two specific settings. This will lead us into discussions on magma, silicate minerals, and the construction of a useful illustration that may be used to both name an igneous rock and determine its mineral content. Igneous rock convergent plate boundaries britannica. These lecture notes are part of a series of lectures available on the geology department website at tulane university. Mechanical deformation and chemical recrystallization are the two processes that affect rock during metamorphism.
Main zone the thickest zone and contains thick monotonous sequences of hypersthene gabbro, norite, and anorthosite figure 126. General classification of igneous rocks tulane university. As a branch of geology, igneous petrology is closely related to volcanology, tectonophysics, and petrology in general. Iugs subcommission on the systematics of igneous rocks. This reader emphasizes how all igneous rocks are formed and explores how the formation is related to igneous rock classification. Stratigraphic sequence of layering in the eastern lobe of the bushveld complex. Change is a result of pressure directed stress and heat solid state reaction no net change in chemistry ideally role of groundwater recrystallization of. Many minerals occur in perfect crystalline form or recrystallized using the chemical constituents of the parent rock, which can be elongated in directions parallel to the. Finegrained at low grade, coarser with increasing grade. Obsidian, for example, was magma hitting water and cooling super fast, so you can barely see the grains, its glassy. Vol 4 no 3 1966 tulane studies in geology and paleontology. Minerals in abundances petrology of associated igneous rocks. Ndsu geosciences petrology 422622 petrology, petrography. This explains why a cooling magma can have some crystals within it.
Soon after geologists began doing chemical analyses of igneous rocks they. Here we give very brief descriptions of most types of terrestrial and lunar igneous rocks, their regional distribution and classification, and examples of their geochemical trends and fingerprints. An introduction to igneous rocks requires exploration of three core ideas. The iugs systematics of igneous rocks article pdf available in journal of the geological society 1485.
Metamorphism involves changes in mineral assemblage and rock texture and occurs in the solid state as a result of changes in temperature and pressure. Papers published during the 19831986 period on the petrology and geochemistry of igneous rocks are discussed, with emphasis on tectonic environment. We started looking at fossils and trying to identify our stuff. Tulane university petrology lecture notes collection.
Igneous petrology is the study of igneous rocksthose that are formed from magma. Petrology of the crust, mantle and core, the convective cycle patterns in the. The overall paper quality group grade is worth 90 points. Igneous rock igneous rock convergent plate boundaries. Here, we look at this magmatism in terms of the volcanic rocks that appear to be related to subduction. Igneous rocks are formed by crystallization from a liquid, or magma. Formation, classification, and identification of igneous rocks next. Hydrothermal activity spatially associated with ultramafic rocks, usually serpentinites, has been observed at several localities proximal. Course notes on optical mineralogy can be found in both html and pdf formats on the tulane university geology dept.
Magma is a mixture of liquid rock, crystals, and gas. Igneous petrology cheat sheet 1 practical igneous petrology for dummies we can all be dummies when it comes to looking at igneous rocks. A magma consists mostly of liquid rock matter, but may contain crystals of various minerals, and may contain a gas phase that may be dissolved in the. It comes from deep in the earth where magma is formed. Igneous rocks associated with convergent plate boundaries have the greatest diversity. Here we discuss a group of plutonic igneous rocks usually referred to. This type of rock may have crystals, air bubbles or a glassy surface. A wide variety of igneous rocks occur in the continental lithosphere, a reflection of its heterogeneous nature compared to oceanic lithosphere.
The most obvious and unequivocal examples are the lavas which have been poured out from presentday volcanoes. Nelson tulane university textures of igneous rocks introduction to igneous rocks an igneous rock is any crystalline or glassy rock that forms from cooling of a magma. Igneous petrology cheat sheet 1 imperial college london. Intrusive or plutonic igneous rocks wherein the magma crystallizes at depth in the earth. Because the continents are not subducted and are subject to uplift and erosion, older plutonic rocks are both preserved and accessible to study.
Physical geology in our overview of the earth, we found out that earths internal heat combined with other mechanisms causes rocks to melt in the asthenosphere and lithosphere. The modern study of igneous rocks utilizes a number of techniques, some of them developed in the fields of chemistry, physics, or other earth sciences. Hand specimen and thin section description of igneous rocks. This document last updated on 12feb2004 eens 212 petrology prof. An impressive and complete set of igneous, sedimentary, and metamorphic petrology lecture notes, in both html and pdf. Mcdermott the basic terminology of igneous petrology. Felsic tuffs, granite hard to tell from arkose when highly metamorphosed.
Forms and structures of igneous rocks springerlink. This is a medium grained intrusive igneous rock of basaltic composition. Metamorphic go 324a rocks and minerals at emporia state. Petrology and genesis of igneous rocks comprises of two parts the first part chapters 1 to 8 deals with constituent minerals, texture, thermodynamic principles, phase relations in natural rock systems and causes of diversity in a single petrographic province. In magma expressed in the form of bowens reaction series. The igneous rocks are those which have solidified from a molten condition. Under the agency of heat and magmatic fluids, ascending magmas pick up volatiles, silica, trace elements, and occassionally fragments of wall rock. An igneous rock is any crystalline or glassy rock that forms from cooling of a magma.
Felsic igneous rocks rhyolites, tuffs, granites if protolith 50% quartz then probably a sandstone or chert. Original igneous, sedimentary, or metamorphic rocks recrystallize without melting, forming minerals and fabrics that are stable under certain pressuretemperature conditions. Atlas of igneous rocks and their textures a companion volume to the atlas of rockforming minerals in thin section, this fullcolour handbook is designed to be used as a laboratory manual both by elementary students of earth sciences undertaking a study of igneous rocks in thin section under the microscope, and by more advanced students and teachers as a reference work. The minerals present in a rock and their relative proportions in the rock depend largely on the chemical composition of the magma. These boundaries are destructive and consume the subducting oceanic lithosphere formed at the. Igneous petrology igneous rocks are assemblages of minerals predominantly rockforming minerals. Classification and nomenclature of igneous rocks prof. Databases of wholerock geochemical analyses for igneous rocks, thermobarometry, isotope geochronology, and plotting. They include two types volcanic or extrusive igneous rocks form when the magma cools and crystallizes on the surface of the earth. In this case, granite batholiths underlie the great composite volcanoes and consist of rocks ranging from basalt through andesite to dacite and rhyolite. Igneous rocks and processes revised on 102011 page 5 of 10 finegrained or aphanitic. They include two types zvolcanic or extrusive igneous rocks form when the magma cools and crystallizes on the surface of the earth. Assimilation is that process of magmatic differentiation whereby ascending magmas evolve chemically by recruiting easily melted or dissolved components from the walls of their conduits.