Bathymetry and Regional Tectonic Setting of the Line Islands Chain

Winterer, El

doi:10.2973/dsdp.proc.33.125.1976

Cited by 22 publications

(23 citation statements)

References 8 publications

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“…The thicknesses of Units 462A-45 to 462A-56 vary from less than 1 m to [rarely] over 30 m (Fig. 2), with modifications after and Winterer (1976). a range similar to the range of thicknesses observed during Leg 61 (< 1 to rarely 50 m) and not very different from the thicknesses of massive flows drilled during Leg 65 (20-m-thick flows were not uncommon) . For further details of the lithology of Units 462A-45 to 462A-56, the reader is referred to the Site 462 chapter (this volume).…”

Section: Lithology and Age Of Basalticmentioning

confidence: 91%

Geochemistry of Basalts from the Nauru Basin, Deep Sea Drilling Project Legs 61 and 89: Implications for the Origin of Oceanic Flood Basalts

Saunders¹

1986

Initial Reports of the Deep Sea Drilling Project

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At Site 462 in the Nauru Basin, western Pacific Ocean, 56 lithologic units have been recovered from an extensive flood basalt province. Fossil evidence suggests that the lavas were emplaced during the interval 100-115 Ma, some 30 m.y. after formation of the underlying Jurassic ocean crust. The lithologic units can be broadly divided into three chemical units, the lowermost two of which are chemically monotonous, suggesting rapid eruption of basalt from a compositionally homogeneous magma chamber. All the basalts are hypersthene-(hy-) rich tholeiites, with approximately chondritic La/Sm, La/Yb, Zr/Nb, La/Ta, and Th/Hf ratios. Chemically they resemble, in part, "transitional" mid-ocean ridge basalts (MORB) from areas such as the Reykjanes Ridge, although Rb, Ba, and K contents are very low and similar to those of "normal" MORB. Their 87 Sr/ 86 Sr ratios are higher than in N-type MORB (Fujii et al., 1981). The chemistry of the Nauru basalts differs from that of continental flood basalts, which tend to be strongly enriched in large-ion lithophile (LIL) elements, although the extent to which the differences result from sialic contamination or source variability is not clear.

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Section: Lithology and Age Of Basalticmentioning

confidence: 91%

Geochemistry of Basalts from the Nauru Basin, Deep Sea Drilling Project Legs 61 and 89: Implications for the Origin of Oceanic Flood Basalts

Saunders¹

1986

Initial Reports of the Deep Sea Drilling Project

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“… Orwig and Kroenke [1980] and Farrar and Dixon [1981] proposed a leaky transform fault origin as an alternative to the hot spot model. Winterer [1976] also suggested that extension along fissures and fractures may have played a role in some of the volcanic activity. On the basis of recovery of potassic rocks similar to those from African rifts, Natland [1976] suggested that the cross trends of the Line Islands might have formed as a result of slow crustal rifting.…”

Section: Introductionmentioning

confidence: 97%

“…Unlike the Hawaiian‐Emperor chain, it is not a discrete chain but comprises multiple strands of parallel to en echelon structures. Repeatedly along its length, groups of seamounts obliquely intersect the main chain, termed “cross‐trends” [ Winterer , 1976]. Owing to the remote location, complexity, and vast length of the chain, it has not been thoroughly studied.…”

Section: Introductionmentioning

confidence: 99%

The Line Islands revisited: New ⁴⁰Ar/³⁹Ar geochronologic evidence for episodes of volcanism due to lithospheric extension

Davis

Gray²,

Clague

et al. 2002

Geochem Geophys Geosyst

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[1] New 40 Ar/ 39 Ar ages of mineral separates and whole rock samples from nine volcanic edifices in the northern Line Islands region, between latitudes 20°N and 6°N, are incompatible with single or multiple hot spot models. Instead, two major episodes of volcanism, each lasting $5 Ma and separated by $8 Ma, occurred synchronously over long distances, not just along the main chain but also at nonaligned edifices. Volcanism during the older episode (81-86 Ma) extended over a distance of at least 1200 km along the eastern part of the complex seamount chain. Volcanism during the younger episode (68-73 Ma) was concentrated in the western part of the chain and may have extended over a distance of >4000 km. Chemical analyses of 68 samples represent a compositionally diverse suite, including tholeiitic, transitional, and alkalic basalt, strongly alkalic basanite and nephelinite, and alkalic differentiates ranging from hawaiite to trachyte. The most diverse assemblage of rocks was recovered from a crosstrending seamount chain south of Johnston Atoll. Although compositions of rocks from the two volcanic episodes overlap, compositions from the younger episode generally are more alkalic and include a larger proportion of highly differentiated compositions. None of the samples from the older episode, but many from the younger one, contain hydrous mineral phases such as amphibole and biotite. Extensive coeval volcanism along major segments of the chain is compatible with decompressional melting of heterogeneous mantle due to diffuse lithospheric extension along pre-existing zones of weakness. Episodes of volcanism are probably related to broad upwarping of the Superswell region in the eastern South Pacific, where these lavas originated.

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“…Many studies proposed that the central and western Pacific basin had been the site of widespread intraplate volcanism during one or two intervals in the Cretaceous (e.g. Matthews et al 1974; Winterer 1976b, a; Rea & Vallier 1983). Menard (1984) suggested the ‘Darwin Rise’ hypothesis from the shallower depth anomaly of the central and western Pacific and the location is consistent with that of present hotspot group in the southeastern Pacific.…”

Section: Discussionmentioning

confidence: 99%

Three-dimensional flexure modelling of seamounts near the Ogasawara Fracture Zone in the western Pacific

Lee¹,

Moon

Jung

2009

Geophysical Journal International

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S U M M A R YThe geophysical data were obtained in 2000-2003 during a survey of seamounts near the Ogasawara Fracture Zone (OFZ) to the northwest of the Marshall Islands in the western Pacific. The OFZ is unique in that it is a wide rift zone showing 600-km-long right-lateral movement between the Pigafetta Basin (PB) and East Mariana Basin (EMB), and contains many seamounts (e.g. the Magellan Seamounts and the seamounts on the Dutton Ridge). Most seamounts in this study are newly mapped using modern multibeam echosounder (Seabeam 2000) and denoted sequentially by Korea Ocean Research and Development Institute (KORDI). OSM2, OSM4, OSM7, OSM8-1 and OSM8-2 seamounts of the study area are located in the OFZ which formed by the spreading ridge between the Izanagi and Pacific plates, and OSM5-1, Seascan, OSM6-1 and OSM6-2 seamounts in the PB which is a part of the oldest oceanic crust in the Pacific. In this study, the densities of seamounts and the elastic thickness values of lithosphere are estimated by using 3-D flexure and gravity modelling by considering several boundary conditions and a constant sediment layer. The infinite model with two different elastic thickness values is the best-fitting model and it indicates that the OFZ was mechanically coupled with plate of different elastic thickness values, probably after the reorganization of Izanagi-Pacific spreading zone. Very low elastic thickness values (5-10 km), relatively young seamounts, and old lithosphere in the east study area suggest the possibility of the rejuvenation of the lithosphere by widespread volcanism pulses, whereas higher elastic thickness values (15-20 km), relatively younger lithosphere, and old seamounts of the west study area are comparable with a simple cooling plate model. It implies that the west study area is outside the rejuvenation range of the lithosphere. In the flexure and gravity modelling, the different residual pattern of OSM6-1 and OSM6-2, which are joined, suggests that they have different load densities or elastic thickness values. OSM2 and OSM7 may be close to a basaltic volcano with low viscosity because they have high densities and ratios of the basal diameter to the height, whereas OSM4, OSM5-1 and Seascan may be close to an andesitic volcano.

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Bathymetry and Regional Tectonic Setting of the Line Islands Chain

Cited by 22 publications

References 8 publications

Geochemistry of Basalts from the Nauru Basin, Deep Sea Drilling Project Legs 61 and 89: Implications for the Origin of Oceanic Flood Basalts

Geochemistry of Basalts from the Nauru Basin, Deep Sea Drilling Project Legs 61 and 89: Implications for the Origin of Oceanic Flood Basalts

The Line Islands revisited: New ⁴⁰Ar/³⁹Ar geochronologic evidence for episodes of volcanism due to lithospheric extension

Three-dimensional flexure modelling of seamounts near the Ogasawara Fracture Zone in the western Pacific

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Bathymetry and Regional Tectonic Setting of the Line Islands Chain

Cited by 22 publications

References 8 publications

Geochemistry of Basalts from the Nauru Basin, Deep Sea Drilling Project Legs 61 and 89: Implications for the Origin of Oceanic Flood Basalts

Geochemistry of Basalts from the Nauru Basin, Deep Sea Drilling Project Legs 61 and 89: Implications for the Origin of Oceanic Flood Basalts

The Line Islands revisited: New 40Ar/39Ar geochronologic evidence for episodes of volcanism due to lithospheric extension

Three-dimensional flexure modelling of seamounts near the Ogasawara Fracture Zone in the western Pacific

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The Line Islands revisited: New ⁴⁰Ar/³⁹Ar geochronologic evidence for episodes of volcanism due to lithospheric extension