The andesite extrusion of Mount Mishennaya, Kamchatka, and its age

Journal Article Classification and Average Chemical Compositions of Common Basalts and Andesites Get access J. F. G. WILKINSON J. F. G. WILKINSON Department of Geology & Geophysics, University of New EnglandArmidale, New South Wales, 2351 Search for other works by this author on: Oxford Academic Google Scholar Journal of Petrology, Volume 27, Issue 1, February 1986, Pages 31–62, https://doi.org/10.1093/petrology/27.1.31 Published: 01 February 1986 Article history Accepted: 18 February 1985 Accepted: 19 April 1985 Published: 01 February 1986

Andesites

10.1093/petrology/27.1.31

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Citations (32)

The Tatara-San Pedro Volcano, 36 S, Chile: A Chemically Variable, Dominantly Mafic Magmatic System

Journal of Petrology (1992)

Kurt M. Ferguson M. A. Dungan Jon P. Davidson M. T. Colucci

The Tatara shield volcano and subsequent San Pedro cone are the youngest edifices of the San Pedro-Pellado volcanic complex at 36°S in the Chilean Andes. There are multiple basaltic andesite compositional types present in the Tatara volcano, which could result from either contrasting source regions or interaction of primitive liquids with heterogeneous crust. The eruptive stratigraphy of the magma types implies concurrent, isolated magma chambers beneath Tatara-San Pedro. Open-system processes and multiple crustal endmembers were involved in calcalkaline differentiation series, whereas a tholeitiic series evolved mainly by fractional crystallization. The glaciated Tatara shield comprises two cycles of compositionally diverse basaltic andesite lavas, each of which is capped by volumetrically minor andesite to dacite lavas. Four types (I-IV) of basaltic andesite are defined on the basis of chemical criteria, two in each cycle. The early cycle consists of calcalkaline type I basaltic andesites, and tholeiitic type II basaltic andesites and andesites; it culminated in the eruption of a dacite dome. The later cycle comprises intercalated calcalkaline type III and IV basaltic andesites, and they are overlain by San Pedro andesites and dacites which appear to be the differentiation products of type IV magmas. Tatara lavas were erupted from a common vent situated beneath the modern San Pedro cone. Although they overlap temporally and spatially, there is little evidence of chemical interaction among the different lava types, indicating that there were two or more magma reservoirs beneath Tatara-San Pedro. Chemical differences among the basaltic andesite types preclude derivation of any one from any of the others by fractional crystallization, assimilation-fractional crystallization (AFC), or magma mixing. The differences seem to reflect chemically different parent magmas. The type I and IV parent liquids were relatively high in MgO, low in CaO and AI2O3, and had high incompatible and compatible element abundances. The type II and III parents were lower in MgO, higher in A12O3 and CaO, and had lower compatible and incompatible element abundances. Tholeiitic type II lavas appear to have evolved mainly by fractional crystallization, whereas there is evidence of open-system processes such as AFC and magma mixing in the evolution of the calcalkaline I, III, and IV suites. The chemical evolution of the type III and type IV-San Pedro magma suites has been simulated by assimilation and mixing models using local granites and xenoliths as assimilants. The xenoliths probably represent portions of a sub-caldera pluton associated with the Quebrada Turbia Tuff, which erupted from the Rio Colorado caldera within the San Pedro-Pellado complex at 0–487 Ma. Chemical and textural variations in type III lavas correlate with stratigraphic position and appear to represent mixing between a parental type III magma and remnant, evolved type I magma that was progressively flushed from its chamber concurrent with mixing. The youngest San Pedro flow is chemically zoned from dacite to basaltic andesite and may have formed by mixing within a conduit during eruption.

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Basaltic andesite

Dacite

Fractional crystallization (geology)

10.1093/petrology/33.1.1

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Citations (55)

Remelting of an Andesitic Crust as a Possible Origin for Rhyolitic Magma in Oceanic Arcs: an Example from the Izu-Bonin Arc

Journal of Petrology (2002)

Yoshihiko Tamura

The Izu–Bonin volcanic arc is an excellent example of an intra-oceanic convergent margin. A total of 1011 chemical analyses of 17 Quaternary volcanoes of the arc are reviewed to estimate relative proportions of magmas erupted. Basalt and basic andesite (SiO2 < 57 wt %) are the predominant eruptive products of the Izu–Bonin arc, and rhyolite (SiO2 > 70 wt %) forms another peak in volume. Such rhyolites possess compositions identical to those of partial melts produced by dehydration-melting of calc-alkaline andesites at low pressure (<7 kbar). Meanwhile, the major element variation of the Shirahama Group Mio-Pliocene volcanic arc suite, Izu Peninsula, completely overlaps that of the Quaternary Izu–Bonin arc volcanoes, and groundmasses of Shirahama Group calc-alkaline andesites have compositions similar to those of Izu–Bonin rhyolites. Moreover, phenocryst assemblages of calc-alkaline andesites of the Shirahama Group resemble restite phase assemblages of dehydration-melting of calc-alkaline andesite. These lines of evidence suggest that the rhyolite magmas may have been produced by dehydration-melting of calc-alkaline andesite in the upper to middle crust. If so, then the presence of large amounts of calc-alkaline andesite (3–5 times more abundant than the rhyolites) within the oceanic arc crust would be expected, which is consistent with a recently proposed structural model across the Izu–Bonin arc. The calc-alkaline andesite magmas may be water saturated, and would crystallize extensively and solidify within the crust. The model proposed here suggests that rhyolite eruptions could be triggered by an influx of hot basalt magma from depth, reheating and partially melting the calc-alkaline andesite component of the crust.

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Basaltic andesite

Volcanic arc

Island arc

Caldera

10.1093/petrology/43.6.1029

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Citations (240)

The Role of the Crust

Minerals and rocks (1981)

James B. Gill

Andesites