What is the calc alkaline rock series?
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. Calc-alkaline rocks are rich in alkaline earths (magnesia and calcium oxide) and alkali metals and make up a major part of the crust of the continents.
What are alkaline igneous rocks?
Alkaline igneous rocks are distinctly enriched in sodium and potassium and contain Na- and/or K-rich minerals such as feldspathoids, alkali pyroxenes, and alkali amphiboles. These rocks occur in continental anorogenic or within-plate tectonic settings where they are related to rifting and/or extensional tectonics.
What is tholeiitic in geology?
tholeiite, fine-grained extrusive igneous rock, a basalt that contains plagioclase feldspar (labradorite), clinopyroxene (augite with pigeonite), and iron ore (magnetite and ilmenite). Tholeiitic lavas often contain glass, but little or no olivine.
What does Subalkaline mean?
: having a hydrogen-ion concentration of 8.0 to 8.5 —used especially of soils of various limestone or salt-marsh regions.
What are alkali rocks?
alkaline rock, any of various rocks in which the chemical content of the alkalies (potassium oxide and sodium oxide) is great enough for alkaline minerals to form. The most common and widely distributed rocks of the world—e.g., granite, granodiorite, andesite, and basalt—do not contain the alkaline minerals.
How is nepheline syenite made?
Nepheline syenite and phonolite may be derived by crystal fractionation from more mafic silica-undersaturated mantle-derived melts, or as partial melts of such rocks. Igneous rocks with nepheline in their normative mineralogy commonly are associated with other unusual igneous rocks such as carbonatite.
How alkaline rocks are formed?
alkaline rock, any of various rocks in which the chemical content of the alkalies (potassium oxide and sodium oxide) is great enough for alkaline minerals to form. Such minerals may be unusually sodium rich, with a relatively high ratio of alkalies to silica (SiO2), as in the feldspathoids.
What is alkaline granite?
Abstract. The alkaline granites of the study area are characterized by the predominance of alkali feldspars, quartz minor amounts of riebeckite, plagioclase and biotite. Accessories are represented by zircon, apatite, titanite, allanite, chevkinite with secondary chlorite.
Is tholeiitic basalt mafic?
Tholeiitic basaltic lavas are characterized by calcic plagioclase with augite, pigeonite or hypersthene, and olivine (rarely) as the dominant mafic minerals; basalts without olivine are also well represented. Tholeiitic basalts, which contain 45 to 63 percent silica, are rich in iron and include the tholeiites…
How is tholeiitic basalt created?
Tholeiitic basaltic magmas are initially generated as partial melts of peridotite (olivine and pyroxene) produced by decompression melting of the Earth’s mantle. In contrast, alkali basalts are not typical of ocean ridges, but are erupted on some oceanic islands and on continents, as also is tholeiitic basalt.
What is alkaline stone?
Which is the best description of the calc alkaline magma series?
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro,…
Which is a subdivision of the subalkaline magma series?
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic.
What kind of magma is in a magma series?
A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in magnesium and iron and produces rhyolite or granite.
Where does the calc-alkaline rock series come from?
Such calcalkaline magmas originate from subduction-contaminated asthenospheric basaltic melts or lithospheric melts through assimilation, fractionation and crystallization processes at different levels in the lithosphere. Physical-chemical controls of continental magmatism evolution remain enigmatic.