Nature of alkalic volcanic rock series

Miyashiro, Akiho

doi:10.1007/bf00376089

Cited by 487 publications

(191 citation statements)

References 47 publications

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“…%) for bulk rock and glass analyses of the Okinawa Trough volcanics. The boundary between the tholeiitic and calc-alkaline rocks is after Miyashiro (1974), and that between alkaline and subalkaline rocks after Miyashiro (1978). The data used were recalculated to 100% volatile free.…”

Section: Glass and Bulk Rock Chemistrymentioning

confidence: 99%

Petrology and geochemistry of volcanic rocks dredged from the Okinawa Trough, an active back-arc basin.

1990

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Volcanic rocks dredged from the Okinawa Trough, an active back-arc basin behind the Ryukyu island arc (IA)-trench system associated with a subduction of the Philippine Sea plate, encompass a wide variety of petrology and geochemistry, ranging from basalts to rhyolites through andesites. The basalts, consisting of highly vesicular pillow lavas, are moderately porphyritic with phenocrysts of olivine, plagioclase and minor clinopyroxene. Their glass and bulk rock compositions , especially their large-ion lithophile element (LILE) abundances, are transitional between the Ryukyu IA basalts (LILE enriched) and normal-type mid-ocean ridge basalts (N-MORBs, LILE-depleted) . The rhyolites are moderately porphyritic, including phenocrysts of plagioclase and orthopyroxene with or without clinopyroxene and hornblende, and have the close geochemical affinity with the Ryukyu IA rhyolites . It follows that the rhyolites were derived from an IA-type source material similar to that for the Ryukyu IA volcanics, but the basalts were derived from a less LILE-enriched source material approaching that for N-MORBs. Available K-Ar ages indicate the rhyolitic volcanism prior to the basaltic one . It is, therefore, most likely that the magma source region beneath the Okinawa Trough has changed with time from an IA type to a N-MORB type during the back-arc rifting. On the other hand , the andesites are highly porphyritic with phenocrysts of plagioclase, orthopyroxene and clinopyroxene , and have the K Ar age similar to that of the basalts. Most importantly, the andesites exhibit many lines of textural and compositional evidence for mixing between basaltic melt, and rhyolitic partial melt of pre-existing IA lower crust that was presumably heated by the former melt. This again suggests the structural transition of the magma source region beneath the Okinawa Trough, which may be most characteristic of the in itial stage of back-arc basin volcanism in general.

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Section: Glass and Bulk Rock Chemistrymentioning

confidence: 99%

Petrology and geochemistry of volcanic rocks dredged from the Okinawa Trough, an active back-arc basin.

1990

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“…5), A1203, FeO*, MgO, and CaO decrease and Na20 and K20 increase with SiO2---total alkali diagram. Alkalic/subalkalic boundary from Miyashiro (1978 (Figs. 6j and 7).…”

Section: Resultsmentioning

confidence: 99%

Geochemistry of igneous rocks of Shimane Peninsula, formed within a Miocene back-arc rifting zone at the Japan Sea margin.

Miyake

1994

Geochem. J.

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“…Almost all samples show sub-alkalic characteristics. Some samples plot in the alkaline field according to the Miyashiro (1978) definition (Fig. 3).…”

Section: Discussionmentioning

confidence: 99%

“…3 Classification of the SSG in total alkalis vs. SiO 2 diagram from Middlemost (1994). The boundaries separating alkaline and sub-alkaline rocks are from Miyashiro (1978) and Irvine and Baragar (1971) arc granite (VAG) and continental collision granite (CCG) fields in an [FeO/(FeO+MgO)/SiO 2 ] diagram after Pearce et al (1984) (Fig. 9).…”

Section: R Hajialioghli M Moazzenmentioning

confidence: 99%

Petrogenetic and tectonic aspects of collisional granitoids from the Sanandaj-Sirjan Belt of Iran

Hajialioghli¹,

Moazzen²

2012

Central European Geology

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The Sanandaj-Sirjan granitoids (SSG) in western Iran are composed mainly of granite, granodiorite and tonalite. Chemically the rocks are peraluminous and metaluminous, and show S-and I-type characteristics. The oval shape of the plutons, with large axes parallel to the Zagros main trend, along with deformational textures and structures, the existence of aluminous minerals such as andalusite, garnet and sillimanite as well as micaceous enclaves and geochemical features, all support generation of these rocks by partial melting of heterogeneous source materials in a continental collision setting, corresponding to the Zagros Orogen.

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Nature of alkalic volcanic rock series

Cited by 487 publications

References 47 publications

Petrology and geochemistry of volcanic rocks dredged from the Okinawa Trough, an active back-arc basin.

Petrology and geochemistry of volcanic rocks dredged from the Okinawa Trough, an active back-arc basin.

Geochemistry of igneous rocks of Shimane Peninsula, formed within a Miocene back-arc rifting zone at the Japan Sea margin.

Petrogenetic and tectonic aspects of collisional granitoids from the Sanandaj-Sirjan Belt of Iran

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