Petrology and Geochemistry of Nauru Basin Igneous Complex: Large-Volume, Off-Ridge Eruptions of MORB-Like Basalt during the Cretaceous

Castillo, Paterno R.; Batiza, Rodey; Stern, R. J.

doi:10.2973/dsdp.proc.89.122.1986

Cited by 18 publications

(8 citation statements)

References 44 publications

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“…Site 802 tholeiites are directly comparable to those of transitional MORB from certain sections of the ocean ridge such as the Reykjanes Ridge and the Costa Rica Rift. In these regards, Site 802 tholeiites are geochemically similar to the tholeiitic basalts recovered at DSDP Site 462 in the Nauru Basin (Larson, Schlanger, et al, 1981;Moberly, Schlanger, et al, 1986;Floyd, 1989;Castillo et al, 1986. The similarity is even more striking because of their identical Sr and Nd isotopic compositions (Fig.…”

Section: Site 802 Tholeiitic Basaltssupporting

confidence: 60%

See 1 more Smart Citation

Isotope Geochemistry of Leg 129 Basalts: Implications for the Origin of the Widespread Cretaceous Volcanic Event in the Pacific

Castillo¹,

Floyd²,

France‐Lanord³

1992

Proceedings of the Ocean Drilling Program

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Section: Site 802 Tholeiitic Basaltssupporting

confidence: 60%

“…Earlier, we have proposed that the Site 462 tholeiites in the Nauru Basin were erupted along an ocean ridge system that propagated into or was formed in the preexisting Jurassic basement when this basement drifted near the intensely volcanically active south central Pacific region during the Cretaceous (Castillo et al, 1986.…”

Section: Discussionmentioning

confidence: 99%

Isotope Geochemistry of Leg 129 Basalts: Implications for the Origin of the Widespread Cretaceous Volcanic Event in the Pacific

Castillo¹,

Floyd²,

France‐Lanord³

1992

Proceedings of the Ocean Drilling Program

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“…Basalts that are very similar in age and chemical and isotopic composition to those from OJP were recovered from EMB to the north of OJP and NB to the east of OJP, at ODP Hole 802A and DSDP Hole 462A, respectively (Figure 1) [ Castillo et al , 1986]. EMB basalts are dated at 114.6 ± 3.2 Ma [ Castillo et al , 1994], while those of NB yielded ages of 110.8 ± 1.0 Ma [ Castillo et al , 1991].…”

Section: General Features and Tectonic Setting Of Ontong Java Plateaumentioning

confidence: 99%

Implications for magmatic processes at Ontong Java Plateau from volatile and major element contents of Cretaceous basalt glasses

Michael

1999

Geochem Geophys Geosyst

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[1] Major elements, Cl, CO 2 , and H 2 O were determined in unaltered tholeiitic basalt glasses from Drilling Program Sites 803D and 807C on Ontong Java Plateau (OJP), and Sites 462A in Nauru Basin (NB) and 802A in East Mariana Basin (EMB). Glasses are moderately evolved (Mg# = 53-60) with low Na 2 O, indicating they formed by large extents of melting. Extent of melting is less for glasses from OJP than from EMB, requiring faster or more focused mantle upwelling or a longer period of activity for OJP.Glasses within each hole define 1-3 different compositional types. Each compositional type is made up of many glass-bounded flow units whose chemistry is identical within analytical uncertainty, suggesting that each compositional type formed during a single eruptive episode with multiple magma surges. The lack of diversity within each type also suggests that the magmatic system was large and well buffered. Major element chemistry also requires that significant shallow crystallization occurred during plateau formation and limits the amount of deep crystallization that might be responsible for the thick crust of the plateau. Chlorine contents are constant within each compositional type and are 580 ppm in type A and 850 ppm in types C-G from Hole 807C, and 360 ppm in glasses from Hole 803D. Glasses from 802A and 462A have $240 ppm and 1975 ppm Cl, respectively. Cl/K ratios range from 0.2 to 2.33, well above mid-ocean ridge basalt (MORB) mantle values (0.07), suggesting that most liquids assimilated hydrothermally altered material as they ascended and crystallized. High Cl/K ratios also suggest that abundant hydrothermal activity may have accompanied plateau formation. Low dissolved CO 2 (i.e., CO 3 2À ) contents in one OJP compositional type (54 ppm in 807C type A) are similar to those on shallow sections of the mid-ocean ridge and are consistent with a maximum depth of eruption of 1320 ± 250 m, in contrast to the greater eruption depths inferred from fossils in the overlying sediments. Our proposed eruption depth falls in the MORB field on a plot of depth versus Na 8.0 supporting a ridge or near-ridge origin. The shallow depth estimate allows for more postformation subsidence and diminishes the importance but does noteliminate the need for additional processes such as prolonged underplating to account for OJP's shallow depth. Higher CO 2 in other glasses, including types C-G from Hole 807C, suggests that some liquids were oversaturated with CO 2 when emplaced and therefore did not travel far from their point of eruption. H 2 O contents are similar to MORB and range from 0.13 wt% for NB, to 0.25 wt% (807C, types C-G) to 0.49 wt% (807C type A). Ratios of H 2 O to rare earth elements (REE) are slightly higher than most MORB and are similar to those from northern Mid-Atlantic Ridge (MAR), which has distinctively high H 2 O. H 2 O/Ce (constant in depleted through enriched MORB) ranges from 200 to 400, compared to 220-380 for northern MAR glasses and 150-250 for MORB elsewhere and >500 for arc-related glasses. The slightly ...

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“…(1976). Nauru Basin data are from Tokuyama and Batiza (1981), Castillo et al . (1986), Floyd (1986, 1989) and Saunders (1986).…”

Section: Discussionmentioning

confidence: 99%

Petrology of the greenstones of the Lower Sorachi Group in the Sorachi–Yezo Belt, central Hokkaido, Japan, with special reference to discrimination between oceanic plateau basalts and mid‐oceanic ridge basalts

Nagahashi¹,

Miyashita

2002

Island Arc

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The Lower Sorachi Group of the Sorachi–Yezo Belt in central Hokkaido, Japan is a peculiar accretionary complex characterized by numerous occurrences of greenstones (metabasalts and diabases), which are mostly composed of aphyric basalts. Clinopyroxene‐rich phenocryst assemblage in phyric basalts is different from olivine–plagioclase assemblage in mid‐oceanic ridge basalts (MORB). The greenstones are geochemically uniform, and show a lower‐Ti trend than MORB in an FeO*/MgO‐TiO2 diagram, mostly plotting on the island arc tholeiite (IAT) field in a TiO2−10MnO−10P2O5 diagram. In a MORB‐normalized spider diagram, the greenstones show a flat pattern from P to Y, which are lower than those of normal mid‐oceanic ridge basalt (N‐MORB). These indicate that the greenstones were derived by a higher degree of partial melting from a depleted mantle similar to a N‐MORB source, and experienced olivine–clinopyroxene fractional crystallization. However, a positive spike of Nb in the spider diagram cannot be explained, and may be attributed to mantle heterogeneity. These characteristics are analogous to those of oceanic plateau basalts (OPB) such as in Ontong Java Plateau, Manihiki Plateau and Nauru Basin, suggesting that the greenstones in the Lower Sorachi Group are of oceanic plateau origin. The present study proposes new field divisions to distinguish OPB from MORB in the conventional FeO*/MgO–TiO2 and TiO2−10MnO−10P2O5 diagrams.

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Petrology and Geochemistry of Nauru Basin Igneous Complex: Large-Volume, Off-Ridge Eruptions of MORB-Like Basalt during the Cretaceous

Cited by 18 publications

References 44 publications

Isotope Geochemistry of Leg 129 Basalts: Implications for the Origin of the Widespread Cretaceous Volcanic Event in the Pacific

Isotope Geochemistry of Leg 129 Basalts: Implications for the Origin of the Widespread Cretaceous Volcanic Event in the Pacific

Implications for magmatic processes at Ontong Java Plateau from volatile and major element contents of Cretaceous basalt glasses

Petrology of the greenstones of the Lower Sorachi Group in the Sorachi–Yezo Belt, central Hokkaido, Japan, with special reference to discrimination between oceanic plateau basalts and mid‐oceanic ridge basalts

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