Despite the general similarity between the johannsen and streckeisen. Terranes in glacier bay national park and preserve, southeast alaska. The acronym, qapf, stands for quartz, alkali feldspar, plagioclase, feldspathoid foid. Slap it on your wall as an educational reminder, or a decorative element. This triangle is a qap diagram, used in geology to identify plutonic igneous rocks by name, based on the modal percentage of the component minerals quartz, alkali feldspar, and plagioclase. But what most people would call granite, geologists prefer to call granitoid until they can get it into the laboratory. The streckeisen qap diagram discriminates four characteristic type series among the large. Qap diagram for volcanic rocks volcanic rocks usually have very small grains aphanitic texture or none glassy texture, so the procedure usually takes a microscope and is rarely performed today.
Explanation of the qapf diagram used to classify igneous rocks. The following tabular statement shows how the principal plutonic rocks are related to one another in respect to the minerals that compose them. Lets first examine the classification of plutonic rocks. Persentase q, a, p, dan f dinormalisasi dihitung ulang agar. In studying igneous rock series, particularly volcanic rocks, petrologists often make use of variation diagrams to show the changes in rock. The scheme requires that the modal composition be known for a particular rock sample. The following rocks represents the main categories of ultramafic rocks. The numbers of the fields are the same as those for plutonic rock classification. Igneous rock is formed through the cooling and solidification of magma or lava. The gray mousepad features a colorful figure, with a title label that says plutonic rock classification, and the definitions of the q, a, and p end members. Albert streckeiseniugsiugssubcommission on the systematics of igneous rocks 1974. Most students of geology will recognize the ternary diagram included below, in glorious ascii as a form of the qap diagram.
The procedure is the same as with the qap diagram for plutonic rocks. The finnish rapakivi granites names of the batholiths are listed in the legend plot in the granite field. Geochronology of plutonic rocks and their tectonic. The qapf diagram is divided into 15 basic fields that define ranges of mineral compositions for the different classes of rocks. Files are available under licenses specified on their description page. The qap ternary diagram is used to classify igneous rocks. Qap diagram for rocks from the biotitehornblende and horn blendebioti te diori te map unit kwdi. The following textural terms are commonly used for plutonic rocks. Gabbro defined by plagioclase with an 50 but for 90% mafics, need a different chart. Pull down the modal menu and select general plutonic qap. Maliand igneous minerals the first step to understand how mali varies in rocks is to note where common igneous minerals plot on a mali diagram fig. Resumen modal analyses provide a precise classification of the plutonic rocks, as demonstrated by the great acceptance of the qapf diagram.
It is based on cipwnormative volcanic, plutonic rocks or modal plutonic rocks contents of albite, anorthite and kfeldspar. A qapf diagram is a double triangle diagram which is used to classify igneous rocks based on mineralogic composition. Qap diagrams showing modal compositions of tertiary plutonic rocks in glacier bay. The generalization in the qapf system, allowing the plotting of undersaturated alkaline series, provides an excellent visual display of the major associations and trends for the plutonic rocks. Geologists plutonic rock qap diagram mouse pad zazzle. Mineralbased classification of plutonic rocks steps are analogous if dioritegabbro. This diagram is used to identify the type of rock based on the modal percentage of quartz, alkali feldspar, and plagioclase it contains. The diagram was created by the subcommission of the systematics of igneous rocks in the latter part of the 20th century.
Rocks with m less than 90 are named according to their positions in the qapf diagram. The magma can be derived from partial melts of existing rocks in either a planets mantle or crust. There are 2 qapf diagrams, one for coarse grained or intrusive igneous rocks, one for fine grained or extrusive igneous rocks. Akronimnya, qapf, merupakan kependekan dari kuarsa, alkali feldspar, plagioklas, dan feldspathoid foid, yang merupakan grupgrup mineral yang digunakan untuk klasifikasi dalam diagram ini. Other minerals may occur in samples, but they are not utilized by this classification method. Earth science science and nature rock identification chemistry 101 rock cycle igneous rock volcanic rock rocks and minerals earth.
Ageochemical classification for feldspathic igneous rocks. Plutonic bodies of a given map unit that possess anomalous compositions and characteristics with respect to the other plutonic bodies of that map unit are high1 ighted in the unit descriptions. Diagram qapf wikipedia bahasa indonesia, ensiklopedia bebas. Igneous rock classification diagrams click the image for a larger version. Plot of the rectilinear grid of the qapfdiagram of streckeisen and le maitre. Hello there, i am studying for a geoscience degree with the open uni and at the moment i am learning how to plot a qap diagram for plutonic igneous rocks but i am confused. They mostly have similar field divisions, so most volcanic rocks have a corresponding. Granophyric igneous rocks and plutonic rocks plotted on an fs di agram 11 figure 4. Igneous rocks constitute one of the three principal classes of rocks, the others being metamorphic and sedimentary.
A classification of volcanic and plufonic rocks using. A qapf diagram is a double ternary diagram which is used to classify igneous rocks based on. Plot on the qap diagram streckeisen, 1976 of plutonic rocks of the montnegre massif. The modal qap diagram constitutes the main tool for the classification of the acidic and intermediate plutonic rocks. This page was last edited on 5 january 2020, at 07.
Plot the estimates on the qap ternary diagram and name each rock using the iugs classification triangle for felsic and intermediate plutonic rocks all attached. The hercynian intrusive rocks of the catalonian coastal ranges ne spain. The hercynian intrusive rocks of the catalonian coastal. I understand how to get the three percentages but i dont understand how you can use them three percentages to identify the. Igneous petrology eosc 321 university of british columbia. Qapf diagrams are not used to classify pyroclastic rocks or volcanic rocks if modal mineralogical composition is not determined, instead the tas. Gokhales method of distinguishing magmatic igneous. Igneous rock classification using diagrams igneous rock. The mali value of plutonic rocks is the sum of the mali values of the constituent minerals.
Plutonic rocks with over 90% mafic minerals m90 are classified according to their mafic minerals and are not plotted on the above diagram. Igneous rock, any of various crystalline or glassy rocks formed by the cooling and solidification of molten earth material. Refer to the lab handout on volcanic rocks because many of the same terms apply to plutonic rocks, e. Pdf the iugs systematics of igneous rocks researchgate. These are the mineral groups used for classification in qapf diagram. Volcanic rocks are commonly fine grained so that modal mineral compositions cannot always be determined. Aphanitic rocks must be classified by chemical, not mineral content. Geology is very complex, natural processes are often impossible to observe metamorphism for example or take place very slowly. Pdf in order to create a sustainable classification of igneous rocks which all geologists. Qapf diagrams are mostly used to classify plutonic rocks phaneritic rocks, but are also. This page was last edited on 20 november 2015, at 20. This wall decal features a qap classification diagram for plutonic rocks. A more informative way to name plutonic rocks geological. Thats because relatively few granite rocks out there are truly petrologically granite.
Typically, the melting is caused by one or more of. Igneous rock derived from the latin word ignis meaning fire, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. According to these data, the composition of the upper crust turned out to be even more anorthositic 82% modal plagioclase on average, which corresponds to 27 parental magmas of lunar troctolites. F and q cannot form in plutonic rocks simultaneously due to the difference in their respective silica contents. Anor classification of the igneous rocks based on their sio2ca.
To use this classification method, the concentration the mode of these minerals must be determined and normalized to 100%. Diagram qapf adalah diagram segitiga bolak balik yang digunakan untuk mengklasifikasikan batuan beku berdasarkan komposisi mineralogi. The streckeisen qap diagram discriminates four characteristic type series among the large variety of granitoids associated in intrusions. Plotting data pull down the options menu and select plot classification. Learn more about the major types of igneous rock, which includes plutonic, intrusive, and extrusive igneous rocks. Classification diagram after oconnor 1965 for silicarich rocks quartz 10 %. Qapf diagram for plutonic rocks geology fundamentals.
Nomenclature of plutonic rocks plotted on the qap diagram. Textures of plutonic rocks university of washington. The selected rock group is displayed in the bottom left hand corner of the spreadsheet. The root names for the classification are given in the diagrams below. Remember that porphyritic rocks have spent time in both worlds. Many volcanic rocks arent suited for this classification method. Modal data for 403 quartzbearing plutonic rocks from the sierra nevada batholith, plotted on the quartzalkali feldsparplagioclase qap triangle and in a tetrahedron whose base is qap and whose apex m represents. All structured data from the file and property namespaces is available under the creative commons cc0 license. Lecture 5 plutonic structures and field relationships friday, february 4th, 2005 figure 420. The qapf diagram is composed of two ternary plots qap and fap joined along one side. View a gallery of igneous rock classification diagrams.
Genetic problems and estimated original compositions. However, it has some limitations and inconsistencies that produce distinct. Learn more about the characteristics of igneous rocks in this article. Granite rock has become so common in homes and buildings that anyone these days can name it when they see it in the field. The modal composition of the plutonic rocks can be quantified but in the case of volcanic.
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