Trace element evidence for the origin of ocean island basalts: an example from the Austral Islands (French Polynesia)

1988 ◽  
Vol 98 (3) ◽  
pp. 293-302 ◽  
Author(s):  
C. Dupuy ◽  
H. G. Barsczus ◽  
J. M. Liotard ◽  
J. Dostal
Keyword(s):  
Trace Element ◽  
French Polynesia ◽  
Ocean Island ◽  
Ocean Island Basalts ◽  
Austral Islands

Distribution of boron, lithium and beryllium in ocean island basalts from French Polynesia: implications for the B/Be and Li/Be ratios as tracers of subducted components

1996 ◽  
Vol 60 (401) ◽  
pp. 563-580 ◽  
Author(s):  
J. Dostal ◽  
C. Dupuy ◽  
P. Dudoignon
Keyword(s):  
Hydrothermal Alteration ◽  
Tectonic Setting ◽  
French Polynesia ◽  
Primitive Mantle ◽  
Fluid Temperature ◽  
Element Abundances ◽  
Ocean Island ◽  
Ocean Island Basalts ◽  
Magmatic Fluids ◽  
Advanced Stages

AbstractThe study focuses on the distribution of B, Be, Li, rare earth elements (REE), high-field-strength elements (HFSE), Th, U and Pb in fresh and hydrothermally altered ocean island basalts (OIB) from French Polynesia, and evaluates B/Be and Li/Be ratios as potential tracers of subducted components in the mantle. Hydrothermal solutions affecting the rocks during cooling were derived from meteoric water, sea water and magmatic fluids. The concentrations of REE, HFSE, Th and Be in the OIB were not affected by secondary processes except during advanced stages of subaerial hydrothermal alteration where saponite was a dominant secondary phase. This alteration modified the contents of these elements, changed REE patterns and produced a positive Ce anomaly. The subaerial and submarine hydrothermal alteration (T ∼ 70–100°C) may change U concentrations in OIB, whereas Pb was only marginally redistributed during alteration.Boron was enriched during submarine and subaerial hydrothermal alteration but was not noticeably affected in basalts altered by magmatic fluids at T > 200°C. Like B, the mobility of Li during the alteration varies with fluid temperature. Lithium became enriched in the basalts during advanced stages of lower T hydrothermal alteration (<100°C). However, this element was partly removed from the rocks during higher T alteration (>200°C) by magmatic fluids. Boron, Be and Li behave as incompatible trace elements in basaltic magmas. Beryllium content in primitive mantle is estimated to be 0.07 ppm. Fresh Polynesian OIB have low abundances of B and Li and low B/Be (2–5) and Li/Be (2.5–5) ratios compared with volcanic arc rocks, marine sediments and altered oceanic crust. Various OIB including even those which have HIMU- and EM-affinities have similar overlapping B/Be and Li/Be ratios. Both B and Li are probably stripped from a lithospheric slab during subduction-related metamorphism and are, thus, not involved in deep mantle recycling. The mantle-normalized trace element abundances of MORB and OIB usually display patterns characterized by negative B, Pb and Li anomalies. The patterns of continental crust and crustal rocks have distinct positive anomalies for these elements whereas continental basaltic rocks have variable relative abundances of B, Pb and Li. The anomalies of these elements in basalts can be useful in discriminating their tectonic setting and constraining the mantle source regions of basalts.

scholarly journals Oxidized Mantle Sources of HIMU and EM-type Ocean Island Basalts

2021 ◽  
Author(s):  
Robert Nicklas ◽  
Rachel Hahn ◽  
Lori Willhite ◽  
Matthew Jackson ◽  
Vittorio Zanon ◽  
...  
Keyword(s):  
Trace Element ◽  
Parental Magma ◽  
Igneous Petrology ◽  
Isotopic Signatures ◽  
Ocean Island ◽  
Radiogenic Isotope ◽  
Ocean Island Basalts ◽  
Enriched Mantle ◽  
Mantle Component ◽  
Ocean Ridge

Oxygen fugacity (fO2) is a fundamental variable in igneous petrology with utility as a potential tracer of recycled surficial materials in the sources of mantle-derived lavas. It has been postulated that ocean island basalts (OIB) have elevated fO2 relative to mid-ocean ridge basalts (MORB) owing to more oxidized source regions. To clarify this issue, trace-element systematics of olivine grains are reported from OIB lavas with HIMU (high-; Mangaia, Canary Islands), enriched mantle (EM; Samoa; São Miguel, Azores Islands) and depleted MORB mantle (DMM; Pico, Azores) Sr-Nd-Pb-Os isotopic signatures, to constrain the fO2 of each magmatic system. Despite sampling distinct mantle reservoirs based on radiogenic isotope systematics, these OIB suites show similar fO2, ranging from +1.5 to +2.9 FMQ, with an average of 2.0 ± 0.7 FMQ, significantly higher than MORB at +0.6 ± 0.2 FMQ using the same oxybarometer. OIBs show no correlation between fO2 and bulk rock isotopic ratios or parental magma compositions. The lack of correlations with isotopic signatures likely results from radiogenic isotope signatures being hosted in volumetrically minor trace element enriched mantle lithologies, while fO2 reflects the volumetrically dominant mantle component. Higher fO2 in OIB relative to MORB implies a uniformly oxidizing plume source mantle that may be the result of either a common oxidized oceanic crust-rich reservoir parental to all modern plume lavas, or preservation of un-degassed and oxidized mantle domains formed early in Earth history.

scholarly journals A trace element perspective on the source of ocean island basalts (OIB) and fate of subducted ocean crust (SOC) and mantle lithosphere (SML)

Episodes ◽  
2012 ◽  
Vol 35 (2) ◽  
pp. 310-327 ◽  
Author(s):  
Yaoling Niu ◽  
Marjorie Wilson ◽  
Emma R. Humphreys ◽  
Michael J. O’Hara
Keyword(s):  
Trace Element ◽  
Mantle Lithosphere ◽  
Ocean Crust ◽  
Ocean Island ◽  
Ocean Island Basalts

scholarly journals Modeling of Olivine and Clinopyroxene Fractionation in Intracontinental Alkaline Basalts: A Case Study from the Carpathian-Pannonian Region

2021 ◽  
Author(s):  
Tamás Sági ◽  
Szabolcs Harangi ◽  
Theodoros Ntaflos
Keyword(s):  
Trace Element ◽  
Fractionation Process ◽  
Ocean Island ◽  
Ocean Island Basalts ◽  
Mantle Peridotites ◽  
Petrology And Geochemistry ◽  
Mantle Petrology ◽  
Basaltic Melts ◽  
Primary Melt

Besides mantle peridotites primary basaltic melts are the best tool to investigate upper mantle petrology and geochemistry. However, de facto primitive melts are hard to found, as basaltic melts usually go through a fractionation process during their ascent towards the surface. Most primary melt calculators are based on the major or trace element compositions of olivine-phyric ocean island basalts and peridotites and are less accurate if clinopyroxene fractionation occurred. In this chapter a new fractionation modeling method of alkaline basalts will be introduced, which has been published earlier only in Hungarian. Olivine ± clinopyroxene fractionation of four basaltic volcanoes have been modeled from different Miocene-Quaternary volcanic fields from the Carpathian-Pannonian Region (Stiavnica (Selmec) VF, Novohrad-Gemer (Nógrád-Gömör) VF, Perşani Mts. (Persányi Mts.) VF and from the Lucaret-Sanoviţa (Lukácskő-Sziklás) volcano.

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