Morphostructure and magnetic fabric of the northwestern North Fiji Basin

Pelletier, Bernard; Lafoy, Y.; Missègue, François

doi:10.1029/93gl01240

Cited by 39 publications

(14 citation statements)

References 8 publications

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“…The southern part of NH also moves at least 20 mm/a westward with respect to PA, because the combined spreading rates of the Central Spreading Ridge and West Fiji Ridge are approximately 100 mm/a [ Auzende et al , 1994, 1995b], exceeding the relative velocity AU‐PA at this latitude (80 mm/a). These constraints suggest a PA‐NH Euler pole of approximately (12°S, 164°E, 1.0°/Ma), which would be consistent with the interpretations of Pelletier et al [1993] and Schellart et al [2002] that spreading rates on the Hazel Holme Ridge decrease westward.…”

Section: Small Platessupporting

confidence: 83%

“…(This may be the only part of the world where marine magnetics researchers quote spreading rates to the nearest cm/a rather than the nearest mm/a.) (2) All authors agree that interpretation of magnetics and topography in this region is difficult, and many postulate multiple tectonic stages since 12 Ma (e.g., 4 stages according to Pelletier et al [1993]). Alternately, this should be viewed as evidence that the data do not have the internal consistency or redundancy that is expected where plates are (approximately) rigid.…”

Section: Small Platesmentioning

confidence: 87%

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An updated digital model of plate boundaries

Bird

2003

Geochem Geophys Geosyst

2,148

1,761

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[1] A global set of present plate boundaries on the Earth is presented in digital form. Most come from sources in the literature. A few boundaries are newly interpreted from topography, volcanism, and/or seismicity, taking into account relative plate velocities from magnetic anomalies, moment tensor solutions, and/or geodesy. In addition to the 14 large plates whose motion was described by the NUVEL-1A poles (Africa, Antarctica, Arabia, Australia, Caribbean, Cocos, Eurasia, India, Juan de Fuca, Nazca, North America, Pacific, Philippine Sea, South America), model PB2002 includes 38 small plates (Okhotsk, Amur, Yangtze, Okinawa, Sunda, Burma, Molucca Sea, Banda Sea, Timor, Birds Head, Maoke, Caroline, Mariana, North Bismarck, Manus, South Bismarck, Solomon Sea, Woodlark, New Hebrides, Conway Reef, Balmoral Reef, Futuna, Niuafo'ou, Tonga, Kermadec, Rivera, Galapagos, Easter, Juan Fernandez, Panama, North Andes, Altiplano, Shetland, Scotia, Sandwich, Aegean Sea, Anatolia, Somalia), for a total of 52 plates. No attempt is made to divide the Alps-Persia-Tibet mountain belt, the Philippine Islands, the Peruvian Andes, the Sierras Pampeanas, or the California-Nevada zone of dextral transtension into plates; instead, they are designated as ''orogens'' in which this plate model is not expected to be accurate. The cumulative-number/area distribution for this model follows a power law for plates with areas between 0.002 and 1 steradian. Departure from this scaling at the small-plate end suggests that future work is very likely to define more very small plates within the orogens. The model is presented in four digital files: a set of plate boundary segments; a set of plate outlines; a set of outlines of the orogens; and a table of characteristics of each digitization step along plate boundaries, including estimated relative velocity vector and classification into one of 7 types (continental convergence zone, continental transform fault, continental rift, oceanic spreading ridge, oceanic transform fault, oceanic convergent boundary, subduction zone). Total length, mean velocity, and total rate of area production/destruction are computed for each class; the global rate of area production and destruction is 0.108 m 2 /s, which is higher than in previous models because of the incorporation of back-arc spreading.

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Section: Small Platessupporting

confidence: 83%

Section: Small Platesmentioning

confidence: 87%

An updated digital model of plate boundaries

Bird

2003

Geochem Geophys Geosyst

2,148

1,761

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“…We suggest this obliquity requires some component of arc‐parallel extension in the back‐arc and likely occurred during the interval 28–20 Ma (Figure ) based on ties to Deep Sea Drilling Project (DSDP) Site 205 [ Davey , ]. Arc‐parallel extension has been similarly interpreted in the North Fiji Basin where magnetic anomalies and spreading ridges strike at high angles to the strike of the New Hebridies arc [ Pelletier et al ., ; Schellart et al ., , ].…”

Section: Discussionmentioning

confidence: 99%

Crustal structure of the Kermadec arc from MANGO seismic refraction profiles

et al. 2016

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Three active‐source seismic refraction profiles are integrated with morphological and potential field data to place the first regional constraints on the structure of the Kermadec subduction zone. These observations are used to test contrasting tectonic models for an along‐strike transition in margin structure previously known as the 32°S boundary. We use residual bathymetry to constrain the geometry of this boundary and propose the name Central Kermadec Discontinuity (CKD). North of the CKD, the buried Tonga Ridge occupies the fore‐arc with VP 6.5–7.3 km s−1 and residual free‐air gravity anomalies constrain its latitudinal extent (north of 30.5°S), width (110 ± 20 km), and strike (~005° south of 25°S). South of the CKD the fore‐arc is structurally homogeneous downdip with VP 5.7–7.3 km s−1. In the Havre Trough back‐arc, crustal thickness south of the CKD is 8–9 km, which is up to 4 km thinner than the northern Havre Trough and at least 1 km thinner than the southern Havre Trough. We suggest that the Eocene arc did not extend along the current length of the Tonga‐Kermadec trench. The Eocene arc was originally connected to the Three Kings Ridge, and the CKD was likely formed during separation and easterly translation of an Eocene arc substrate during the early Oligocene. We suggest that the first‐order crustal thickness variations along the Kermadec arc were inherited from before the Neogene and reflect Mesozoic crustal structure, the Cenozoic evolution of the Tonga‐Kermadec‐Hikurangi margin and along‐strike variations in the duration of arc volcanism.

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“…[9] The termination of subduction along the Vitiaz Trench led to a reversal of arc polarity northwest of Fiji along the Vanuatu-New Hebrides segment around 12-8 Ma [Auzende et al, 1996;Pelletier et al, 1993;Hamburger and Isacks, 1987;Gill and Whelan, 1989a;Crawford et al, 2003]. Clockwise rotation of the Vanuatu arc resulted in the initial opening of the North Fiji Basin along a NW-SE spreading axis [Auzende et al, 1996].…”

Section: Tectonic Settingmentioning

confidence: 99%

Primitive shoshonites from Fiji: Geochemistry and source components

Leslie

Danyushevsky

Crawford

et al. 2009

Geochem Geophys Geosyst

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[1] The eruption of shoshonitic magmas in Fiji during the Late Miocene-Pliocene (5.5-3 Ma) from 11 main volcanic centers along three broad ENE and NNW trending lineaments coincides with welldeveloped spreading in the North Fiji and Lau back-arc basins and maximum rotation of the Fiji Platform. The most mafic shoshonitic lavas (absarokites) range from 8.4 to 15.2 wt % MgO and are variably clinopyroxene + olivine-phyric. Fijian shoshonitic suites display a range of enrichment in large ion lithophile elements, Th, U, and P relative to rare earth elements and high field strength elements (HFSE), reflecting variable contributions by the subarc mantle source and subduction-related components. The subarc mantle source component controls HFSE, heavy rare earth elements, to a lesser degree light rare earth elements (LREE), and most importantly the sensitivity of the mantle source with respect to subduction-related enrichment processes, whereas Pb, K, Sr, Ba, Rb, Th, U, P 2 O 5 , and LREE are contributed by hydrous or supercritical fluid(s) and sediment melts that are added to the subarc mantle. Fijian shoshonitic suites situated $150 km apart display a wide range of Nb/Yb (0.3-4.3), implying that there is significant spatial heterogeneity in the sub-Fijian mantle with respect to the ambient fertility of mantle sources independent of subduction-related enrichment. The range in incompatible element ratios (e.g., Th/Nb, U/Nb, Ba/Th, Ba/La, P/Nd, and Ce/Pb) displayed by Fijian shoshonitic suites cannot reflect addition of the same subduction-derived component to variably enriched subarc mantle sources. Differences in the relative amount of fluid versus sediment melt and potentially the composition of the subducted sediment are required to explain the data. The greater overall subduction-related enrichment in Fijian shoshonites relative to calk-alkaline and tholeiitic arc magmas is attributed to a melt generation process involving low-degree partial melting of metsomatized subarc lithosphere in contrast to magmas associated with active or steady state arcs, where higher degrees of melting occur in response to volatile fluxing of the mantle wedge. Shoshonitic magma generation occurs in linear zones during extension of the arc lithosphere preceding arc fragmentation and establishment of back-arc spreading centers.

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Morphostructure and magnetic fabric of the northwestern North Fiji Basin

Cited by 39 publications

References 8 publications

An updated digital model of plate boundaries

An updated digital model of plate boundaries

Crustal structure of the Kermadec arc from MANGO seismic refraction profiles

Primitive shoshonites from Fiji: Geochemistry and source components

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