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The tholeiitic magma series (/ ˌ θ oʊ l i ˈ aɪ t ɪ k /) 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 ...
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 ...
Tholeiitic magma series rocks are found, for example, at mid-ocean ridges, back-arc basins, oceanic islands formed by hotspots, island arcs and continental large igneous provinces. [ 24 ] All three series are found in relatively close proximity to each other at subduction zones where their distribution is related to depth and the age of the ...
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 ...
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 ...
Geologists have sub-divided the basalts between older series of basanite and hawaiite, which are intruded by many, younger nephelinite and basanite basalt dikes. The older basalts contain phenocrysts of olivine, titanaugite , titano-magnetite and plagioclase, with a matrix of smaller crystals of all of the same minerals except for olivine.
The 2.9 to 2.15 billion year old volcanic belts formed from a tholeiitic magma series that experienced low-grade metamorphism and was intruded by granitoids. The sedimentary basins have isoclinal folding and contain dacite volcaniclastic rocks, greywacke and argillite.
The OJP basaltic basement is four tholeiitic magma series called the Kwaimbaita, Kroenke, Singgalo, and Wairahito. [8] All except the Singgalo are isotopically identical so they are likely from the same mantle source. [8] It can be assumed that the Singgalo basalts have a different mantle source to the rest.