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Rocks in the alkaline magma series are distinguished from rocks in the subalkaline tholeiitic and calc-alkaline magma series by their high content of alkali metal oxides (K 2 O plus Na 2 O) relative to silica (SiO 2). They are distinct from the rare peralkaline magmas, which have excess alkali oxides relative to alumina (Na 2 O + K 2 O > Al 2 O 3).
The tholeiitic magma series (/ ˌθoʊliˈaɪtɪk /) is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member. Rock types of the tholeiitic ...
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. 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 ...
Esterellite (or Estérellite) is a porphyritic variety of quartz-bearing microdiorite, containing phenocrysts of quartz, zoned andesine, and hornblende only found in the southern part of the Esterel massif, between Agay and Saint-Raphael, France. [ 1] It is a bluish-grey rock, sometimes greenish, dotted with white plagioclase feldspar and ...
Hawaiite is sodic trachybasalt. Hawaiite is an aphanitic (fine-grained) volcanic rock produced by rapid cooling of lava moderately poor in silica and enriched in alkali metal oxides (potassium oxide plus sodium oxide). It is often impractical to determine the mineral composition of such a fine-grained rock, and so hawaiite is defined chemically.
Trachyandesite is an extrusive igneous rock with a composition between trachyte and andesite. It has little or no free quartz, but is dominated by sodic plagioclase and alkali feldspar. It is formed from the cooling of lava enriched in alkali metals and with an intermediate content of silica. [1][2]
In geology, igneous differentiation, or magmatic differentiation, is an umbrella term for the various processes by which magmas undergo bulk chemical change during the partial melting process, cooling, emplacement, or eruption. The sequence of (usually increasingly silicic) magmas produced by igneous differentiation is known as a magma series.
The Red Hill Syenite is part of the White Mountain magma series, which underlays the White Mountains of New Hampshire. Red Hill is roughly oval-shaped, covers just under 7.7 square miles (20 km 2 ), and has a summit elevation of 2,028 feet (618 m).