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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 ...
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).
Volcanic arcs are characterized by explosive eruption of calc-alkaline magma, though young arcs sometimes erupt tholeiitic magma [7] and a few arcs erupt alkaline magma. [8] Calc-alkaline magma can be distinguished from tholeiitic magma, typical of mid-ocean ridges, by its higher aluminium and lower iron content [9]: 143–146 and by its high ...
The volume of magma erupted from Mazama during this eruption was 14 cubic miles (61 km 3). [68] The lava produced was zoned vertically according to arrangement within the source magma chamber, and was calc-alkaline in composition. [69]
Dacitic magma was encountered in a drillhole during geothermal exploration on Kīlauea in 2005. At a depth of 2488 m, the magma flowed up the wellbore. This produced several kilograms of clear, colorless vitric (glassy, non-crystalline) cuttings at the surface. The dacite magma is a residual melt of the typical basalt magma of Kīlauea. [16]
The magmatism is mostly calc-alkaline in type along a well-defined curvilinear magmatic arc. Only the volcanic parts of modern arcs are exposed at the surface and the understanding of the underlying magma chambers relies on geophysical methods. Ancient arc sequences that formed on continental crust or that have become accreted to continental ...
Stratigraphic range: ... The group is chiefly made up of pyroclastic rocks and lavas of the calc-alkaline magma series. [1] Rocks are of andesite and rhyolite ...
English: The AFM diagram, a ternary diagram between the Alkali, Fe, and Mg oxides used to distinguish the calc-alkaline magma series from the tholeiitic magma series. Key/Legend: A–alkali (sodium and potassium) oxides, F–iron oxides, M–magnesium oxide, BT–tholeiitic basalt, FB–ferro-basalt, ABT–tholeiitic basaltic andesite, AT–tholeiitic andesite, D–dacite, R–rhyolite, B ...