A two‐dimensional seismic investigation of crustal structure under the Hawaiian Islands near Oahu and Kauai

Lindwall, Dennis

doi:10.1029/jb093ib10p12107

Cited by 56 publications

(47 citation statements)

References 38 publications

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“…In such an interpretation, the underplate could be regarded as closely related to active volcanism and vanishing with time, so that no underplate would be distinguishable under the older parts of the hotspot track. If the underplating were absent on the transect of the old Hawaiian chain near Oahu, as advocated by Lindwall [1988] in his reassessment of seismic data, which challenges the interpretation of a large volume of underplating [Watts et al, 1985], this would agree with the model of a transient structure.…”

Section: Heterogeneity Of the Edifice Under The Island: Implication Fsupporting

confidence: 56%

Perturbation to the lithosphere along the hotspot track of La Réunion from an offshore‐onshore seismic transect

Muset¹,

Driad²,

Charvis³

et al. 1999

J. Geophys. Res.

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Abstract. A 250 km long NE-SW lithospheric transect spanning the 40 km wide island of La R6union and its submarine edifice is derived from lines of air gun shots at sea on either side, along the assumed hotspot trace. Seismic records were obtained from an array spanning the whole transect and including sea bottom and land receivers, providing a system of reversed and overlapping observations. Low seismic velocity, and hence density, is found on average for the whole edifice above the oceanic plate. We attribute highvelocity anomalies within the edifice to an intrusive core confined under the central northern quarter of the island-crossing segment. Unexpectedly, the main seismic interfaces, top and bottom of the prevolcanic crust, do not show significant flexural downwarping under the island. In addition, clear multipathing in the recorded wave field requires the presence of a body with a seismic velocity intermediate between the prevolcanic crustal material and the normal mantle. This lithospheric structure provides the first example where underplating occurs beneath an active volcanic island, suggesting a genetic relationship. The underplated body could represent residues of the evolution of primary picritic melts that yield erupted basalts. Evidence for reflectors deeper in the lithosphere may indicate further related heterogeneity. In the plate/hotspot model commonly assumed, the structural variation along the transect could be interpreted as a variation with time of the amount and physical state of underplated material. Active volcanism rather than plate flexure being the prime target, the long transect presented here is directed SW-NE along the supposed hotspot trace in order to sense the variation in structure of the lithospheric plate from its intact state before, during, and after having been submitted to the magmatic discharge of the mantle plume. The main refraction profile described here was recorded at sea by five OBS on the SW segment of the line of shots and two OBS on the NE segment (Figure 1), as well as on land in between by 32 por- The multiple-receiver recording of seismic shot lines achieved is fundamentally important in wide-angle reflectionrefraction seismics in order to obtain wave propagation along a system of reversed and overlapping profiles. Only such a cross sampling may resolve the variation of velocity with depth (layering) and the lateral variation of velocity (dip of interfaces or lateral heterogeneity within layers) from each other. Trialand-error forward modeling then results in a two-dimensional (2-D) seismic velocity structure consistently but not uniquely accounting for the observations. In such a model, those elements required by data that are critical by their quality or sampling may not stand out from other ones that are less constrained. Therefore the present section is devoted to displaying crucial data and commenting on particular aspects of the structural model they constrain before the derivation of the 2-D velocity model in section 3.The most relevant features, illus...

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Section: Heterogeneity Of the Edifice Under The Island: Implication Fsupporting

confidence: 56%

Perturbation to the lithosphere along the hotspot track of La Réunion from an offshore‐onshore seismic transect

Muset¹,

Driad²,

Charvis³

et al. 1999

J. Geophys. Res.

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“…Seismic reflection and refraction data, already in the past, have highlighted the existence of an abnormal thickness of the transition zone C-M [about [3][4][5][6] Km] extending in a 200-km-wide area centered at Ohau island, in accordance with the previous petrologic models involving accumulation of upwelling magma at and below the Moho (Figure 19). The existence of such a large volume of intrusions near the base of the crust [magmatic underplating] implies that the superficial expression of volcanism constitutes only a small fraction of the amount of melt generated at depth under the Hawaiian Islands (5).…”

Section: Discussionsupporting

confidence: 59%

The pockmark stars: radial structures in the seabed surrounding the Hawaii Islands

Spina

2017

J Environ Geol

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“…Maximum crustal thickness across the swell of the Hawaiian hotspot near Oahu and Kauai islands is 14^15 km, whereas normal crustal thickness of the Paci¢c plate is V7 km. The across-ridge width of the overthickened crustal section is V400 þ 25 km [53]. Based on the model NUVEL-1A, the Paci¢c plate is moving at approximately 105 þ 5 km/m.y.…”

Section: Volumetric Melt £Ux For Excess Crustal Productionmentioning

confidence: 99%

Crustal thickness constraints on the geodynamic evolution of the Galapagos Volcanic Province

Sallarès

Charvis

2003

Earth and Planetary Science Letters

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We developed a simple quantitative framework based on crustal thickness estimations along the Carnegie, Cocos and Malpelo ridges, to place first-order constraints on the tectonic evolution of the Galapagos Volcanic Province and on the along-axis intensity of the Galapagos melt anomaly during the last 20 m.y. Our results suggest that the CocosN azca spreading centre has migrated northwards at 26 þ 4 km/m.y. with respect to the Galapagos hotspot (GHS) during this period of time. At V20 m.y., the GHS was approximately ridge-centered, and thus the along-axis intensity of the melt anomaly at this time was the maximum. At V11.5 m.y. the hotspot was located 106 þ 27 km north of the spreading center, and the along-axis intensity of the melt anomaly was 0.54 þ 0.04 of that estimated at 20 Ma. At present day it is located at V190 km south of the spreading center and the along-axis intensity is only 0.19 þ 0.03 of that estimated at 20 Ma. These results are used to reconstruct the relative position between the GHS and the CocosN azca Spreading Center. The spreading center passed over the GHS for the last time at 7.4 þ 1.3 Ma. The Panama fracture zone was initiated at 8.9 þ 1.6 Ma, leading to the separation between the Cocos and Malpelo ridges. The present configuration of the Galapagos Volcanic Province and the plate velocities are consistent with symmetric spreading with a mean full spreading rate of V60 km/m.y. along the CNSC during the last 20 m.y. A melt flux for excess crustal production of 9.4 þ 5.1 m 3 /s is obtained for the Galapagos melt anomaly at 20 Ma, implying that the maximum potential intensity of the Galapagos plume is similar to that of the Icelandic plume and twice smaller than the Hawaiian one. ß

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A two‐dimensional seismic investigation of crustal structure under the Hawaiian Islands near Oahu and Kauai

Cited by 56 publications

References 38 publications

Perturbation to the lithosphere along the hotspot track of La Réunion from an offshore‐onshore seismic transect

Perturbation to the lithosphere along the hotspot track of La Réunion from an offshore‐onshore seismic transect

The pockmark stars: radial structures in the seabed surrounding the Hawaii Islands

Crustal thickness constraints on the geodynamic evolution of the Galapagos Volcanic Province

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