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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 ...
The alkaline series – subgroups of alkaline basalts and the rare, very high potassium-bearing (i.e. shoshonitic) lavas. This volcanic series is related to the age of the subduction zone and the depth. The tholeiitic magma series is well represented above young subduction zones formed by magma from relative shallow depth.
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.
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.
Three magma series of volcanic rocks are found in association with arcs. The chemically reduced tholeiitic magma series is most characteristic of oceanic volcanic arcs, though this is also found in continental volcanic arcs above rapid subduction (>7 cm/year). This series is relatively low in potassium.
The erupted rocks are from the tholeiitic magma series and picrite basalt. [4] There is not a central volcano, but rather a number of flat-topped, elongated ridges arranged in enechelon fashion. [4] Conical-, fissure- or shield-like volcanoes are superimposed on these ridges.