Ages, rare-earth element enrichment, and petrogenesis of tholeiitic and alkalic basalts from Kahoolawe Island, Hawaii

Fodor, R. V.; Frey, Frederick A.; Bauer, G. R.; Clague, David A.

doi:10.1007/bf00344080

Cited by 83 publications

(33 citation statements)

References 35 publications

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“…The suggestion that lavas of the postshield alkalic cap fractionated at greater depths in the volcanic edifice than the shield lavas also has been found from studies of Mauna Kea (West and Leeman 1987;Frey et al 1990Frey et al , 1991, Hualalai (Clague 1987), Kohala (Spengler and Garcia 1988), Kahoolawe (Fodor et al 1992), and East Molokai (Beeson 1976). Thus, a general trend of high-pressure fractionation giving rise to postshield, differentiated alkalic magmas has emerged for Hawaiian magmatic evolution.…”

Section: Depth Of Magma Evolutionmentioning

confidence: 84%

“…Palehua magmas fractionated olivine c plagioclase c clinopyroxene c oxide, whereas Kolekole magmas appear to have fractionated only olivineBclinopyroxene. Studies of lavas from Mauna Kea , Kohala (Feigenson 1983;Lanphere and Frey 1987;Spengler and Garcia 1988), Molokai (Beeson 1976), and Kahoolawe (Fodor et al 1992) all have concluded that the differentiated alkalic postshield lavas have fractionated clinopyroxene as a major constituent in the fractionating assemblage, possibly as a near-liquidus phase. The CaO/Al 2 O 3 ratio is particularly sensitive to clinopyroxene fractionation, and the variation evident in Fig.…”

Section: Depth Of Magma Evolutionmentioning

confidence: 96%

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Postshield volcanism and catastrophic mass wasting of the Waianae Volcano, Oahu, Hawaii

Presley

Sinton

Pringle

1997

Bulletin of Volcanology

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The 3.9-to 2.9-Ma Waianae Volcano is the older of two volcanoes making up the island of Oahu, Hawaii. Exposed on the volcanic edifice are tholeiitic shield lavas overlain by transitional and alkalic postshield lavas. The postshield "alkalic cap" consists of aphyric hawaiite of the Palehua Member of the Waianae Volcanics, overlain unconformably by a small volume of alkalic basalt of the Kolekole Volcanics. Kolekole Volcanics mantle erosional topography, including the uppermost slopes of the great Lualualei Valley on the lee side of the Waianae Range. Twenty new K-Ar dates, combined with magnetic polarity data and geologic relationships, constrain the ages of lavas of the Palehua member to 3.06-2.98 Ma and lavas of the Kolekole Volcanics to 2.97-2.90 Ma. The geochemical data and the nearly contemporaneous ages suggest that the Kolekole Volcanics do not represent a completely independent or separate volcanic event from earlier postshield activity; thus, the Kolekole Volcanics are reduced in rank, becoming the Kolekole Member of the Waianae Volcanics. Magmas of the Palehua and Kolekole Members have similar incompatible element ratios, and both suites show evidence for early crystallization of clinopyroxene consistent with evolution at high pressures below the edifice. However, lavas of the Kolekole Member are less fractionated and appear to have evolved at greater depths than the earlier Palehua hawaiites. Postshield primary magma compositions of the Palehua and Kolekole Members are consistent with formation by partial melting of mantle material of less than 5-10% relative to Waianae shield lavas. Within the section of Palehua Member lavas, an increase with respect to time of highly incompatible to moderately incompatible element ratios is consistent with a further decrease in partial melting by approximately 1-2%. This trend is reversed with the onset of eruption of Kolekole Member lavas, where an increase in extent of partial melting is indicated. The relatively short time interval between the eruption of Palehua and Kolekole Member lavas appears to date the initial formation of Lualualei Valley, which was accompanied by a marked change in magmatic conditions. We speculate that the mass-wasting event separating lavas of the Palehua and Kolekole Members may be related to the formation of a large submarine landslide west and southwest of Waianae Volcano. Enhanced decompression melting associated with removal of the equivalent volume of this landslide deposit from the edifice is more than sufficient to produce the modeled increase of 1-2% in extent of melting between the youngest Palehua magmas and the posterosional magmas of the Kolekole Member. The association between magmatic change and a giant landsliding event suggests that there may be a general relationship between large mass-wasting events and subsequent magmatism in Hawaiian volcano evolution.

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Section: Depth Of Magma Evolutionmentioning

confidence: 84%

Section: Depth Of Magma Evolutionmentioning

confidence: 96%

Postshield volcanism and catastrophic mass wasting of the Waianae Volcano, Oahu, Hawaii

Presley

Sinton

Pringle

1997

Bulletin of Volcanology

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“…Other elements that we searched for but did not find in detectable amounts are Zn, Co, Rb, Nb and Zr, and we conclude that the low summations Fodor et al, 1992a), and a comparative reference to the R E E pattern for historic Kilauea tholeiite (Budahn and Schmitt, 1985). (bottom) R E E patterns for hollandite in sample 112 (note: element Y replaces Dy position in pattern) and for a Mn-nodule (sample wah 2 pg of Elderfield et al, 1981), both with positive Ce anomalies, compared to historic Kilauea tholeiite.…”

Section: Analytical Proceduresmentioning

confidence: 62%

“…In addition to Ce, the Mn oxides appear to have accommodated appreciable amounts of total REE and Y that were transient due to a seemingly rare secondary process that leaches these elements from Hawaiian lavas (Fodor et al, 1992a). While this is not the first indication that Mn-oxides in terrestrial environments can fix mobile REE and Y (e.g.…”

Section: Discussionmentioning

confidence: 93%

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Hollandite in Hawaiian basalt: a relocation site for weathering-mobilized elements

Fodor

Jacobs²,

Bauer³

1994

Mineral. mag.

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Enrichments in Ba, REE and Y abundances, occurrences of REE, Y-bearing phosphate, depletions in K and Rb, and negative Ce anomalies in some lavas on Kahoolawe (Hawaii) reflect secondary mobilization of Ba, REE, Y, K and Rb. Hollandite (Ba-Mn-oxide) in the groundmass of a Kahoolawe lava contains nearly 10 wt.% BaO, ~ 1.1 wt.% CeO2, and small amounts of La, Nd, Y, K, Na, P, C1 and Cu to provide an example of where elements mobilized during weathering processes on the Hawaiian Islands find residence. Fe-vernadite, a second Mn-oxide, also hosts mobilized REE and Ba. A positive Ce anomaly in the hollandite complements the negative Ce anomaly in some Kahoolawe lavas, this is analogous to Ce accumulation in todorokite of manganese nodules complementing Ce-depleted seawater. Mn-oxides, then, can serve as links between lavas depleted and enriched in certain elements.

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Petrology of ultramafic and mafic xenoliths in picrite of Kahoolawe Island, Hawaii

1992

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Ages, rare-earth element enrichment, and petrogenesis of tholeiitic and alkalic basalts from Kahoolawe Island, Hawaii

Cited by 83 publications

References 35 publications

Postshield volcanism and catastrophic mass wasting of the Waianae Volcano, Oahu, Hawaii

Postshield volcanism and catastrophic mass wasting of the Waianae Volcano, Oahu, Hawaii

Hollandite in Hawaiian basalt: a relocation site for weathering-mobilized elements

Petrology of ultramafic and mafic xenoliths in picrite of Kahoolawe Island, Hawaii

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