Petrochemistry, age and isotopic composition of alkali basalts from Ponape Island, western Pacific

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doi: 10.1016/0009-2541(84)90138-4
Authors:Dixon, T. H.; Batiza, R.; Futa, K.; Martin, D.
Author Affiliations:Primary:
Jet Propul. Lab., Pasadena, CA, United States
Wash. Univ., Dep. Earth and Planet. Sci., United States
U. S. Geol. Surv., United States
San Diego State Univ., United States
Volume Title:Chemical Geology
Source:Chemical Geology, 43(1-2), p.1-28. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541
Publication Date:1984
Note:In English. 63 refs.; illus. incl. 5 tables, sketch maps
Summary:Analysed lava samples (11) from this island are alkali-olivine basalt, and basanitoid, similar to those found elsewhere in oceanic island volcanoes. The sampled lavas are generally fresh, and most of them are fractionated. Only one sample could represent a primary melt of the Fo88-90-rich upper mantle and its olivine composition (Fo79) suggests that even this has undergone some fractionation. Major- and trace-element data and partial melting models suggest that a likely parental composition for the Ponape lavas originated by 3-12% partial melting of a pyrolitic source. Trace-element characteristics of this source were partly chondritic, but may have been enriched in LREE and some other incompatible trace elements with respect to chondrites. The fractionated lavas of Ponape have a complex origin, possibly including variable source concentration of a trace-element-rich minor phase. Age data for this island are not compatible with a simple hot-spot origin. The Caroline Ridge may owe its origin to deep lithospheric fractures related to the separate development of the Caroline plate. Selected major-oxide analyses of 9 olivines, 7 plagioclases, 12 pyroxenes, and 10 Fe-Ti-oxides, sphenes and spinels are presented, with 11 whole-rock major- and trace-element analyses, and CIPW norms. K/Ar age data for 5 samples, the O- and Sr-isotopic compositions of 7 lavas, and Nd analyses of 4 lavas are also given. [P.Br.]
Subjects:Absolute age; Alkaline earth metals; Basalts; Basanite; Dates; Differentiation; Fractional crystallization; Geochemistry; Igneous rocks; Inclusions; Island arcs; Isotopes; K/Ar; Magmas; Mantle; Metals; Nd-144/Nd-143; Neodymium; O-18/O-16; Olivine basalt; Oxygen; Petrology; Rare earths; Sr-87/Sr-86; Stable isotopes; Strontium; Textures; Trace elements; Volcanic rocks; Weathering; Xenoliths; Caroline Islands; Equatorial Pacific; Micronesia; Oceania; Pacific Ocean; West Pacific; Ponape Island; Ratios; Senyavin
Coordinates:N050000 N080000 E1590000 E1563000
Abstract Numbers:84M/4436
Record ID:1985008974
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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