Journal article
Petrology and Geochemistry of the Island of Sarigan in the Mariana ARC; Calc-Alkaline Volcanism in an Oceanic Setting
Contributions to mineralogy and petrology, Vol.77(4), pp.337-354
1981
DOI: 10.1007/BF00371563
Abstract
Isotopic studies of rocks from oceanic island arcs such as the Marianas indicate that little, if any, recycling of continental material (e.g. oceanic sediments) occurs in these arcs. Because oceanic arcs are on the average more mafic than the dominantly andesitic continental arcs, an important question is whether the andesites of continental arcs are produced by a fundamentally different (more complex?) mechanism than the lavas of oceanic arcs. An excellent opportunity for study of this question is provided by the island of Sarigan, in the Mariana active arc, on which calc-alkaline andesites (including hornblende-bearing types) are exposed along with more mafic lavas. Available isotope data suggest the Sarigan lavas (including the andesites) were derived from mantle material with little or no involvement of continental components. Ratios of incompatible elements suggest that most of the Sarigan lavas were derived from similar source materials. Absolute abundances of incompatible elements vary irregularly within the eruptive sequence and indicate at least 5 distinct magma batches are represented on Sarigan. Major element data obtained on the lavas and mineral phases in them, combined with modal mineral abundances, suggest that the calc-alkaline nature of the volcanic rocks on Sarigan results from the fractional crystallization of titanomagnetite in combination with other anhydrous phases. Amphibole, although present in some samples, is mainly a late-crystallizing phase and did not produce the calc-alkline characteristics of these lavas. Gabbroic samples found in the volcanic sequence have mineralogc and geochemical characteristics that would be expected of residual solids produced during fractional crystallization of the Sarigan lavas. When combined, data on the lavas and the gabbros suggest the following crystallization sequence: olivine - plagioclase - clinopyroxene - titanomagnetite - orthopyroxene±hornblende, biotite and accessory phases. These results lead to the conclusion that calc-alkaline magmas can be generated directly from mantle sources. © 1981 Springer-Verlag.
Details
- Title: Subtitle
- Petrology and Geochemistry of the Island of Sarigan in the Mariana ARC; Calc-Alkaline Volcanism in an Oceanic Setting
- Creators
- A Meijer - University of ArizonaM Reagan - University of Arizona
- Resource Type
- Journal article
- Publication Details
- Contributions to mineralogy and petrology, Vol.77(4), pp.337-354
- Publisher
- Springer
- DOI
- 10.1007/BF00371563
- ISSN
- 0010-7999
- eISSN
- 1432-0967
- Language
- English
- Date published
- 1981
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984229173202771
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