Recent tectonics associated with the subduction/ collision of the d'entrecasteaux Zone in the central New Hebrides

Collot, Jean‐Yves; Daniel, Jacques; Burne, Robert V.

doi:10.1016/0040-1951(85)90185-4

Cited by 117 publications

(124 citation statements)

References 26 publications

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“…The geodetic rotation rates are comparable to those obtained from paleomagnetic studies [e.g., Otofuji et al, 1981;Surmont et al, 1994;Walpersdorf et al, 1998a] Collot et al, 1985;Pelletier et al, 1998;Calmant et al, 2003]. In Vanuatu, collision of the West Torres Plateau with the New Hebrides Trench occurred $0.7 Ma ago [Greene and Collot, 1994], while collision of the D'Entrecasteaux Ridge began earlier, at either $1.5-3 Ma ago [Greene and Collot, 1994] or $8 -10 Ma ago [Meffre and Crawford, 2001].…”

Section: A22 Present-day Examples Withoutsupporting

confidence: 76%

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

Wallace

Ellis

Mann

2009

Geochem Geophys Geosyst

102

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[1] We review geophysical and geological data from 23 active and ancient plate boundaries to document a compelling spatial and temporal relationship between collision, plate boundary curvature, rapid tectonic rotations, and the occurrence of back-arc rifting. Our observations support a conceptual model where the change from subduction to collision causes rapid fore-arc rotation (when viewed in a reference frame relative to the bounding tectonic plates), leading to marked plate boundary curvature. Our global compilation reveals that most active back-arc rifts are associated with rapidly rotating fore arcs and nearby collisions. Thus, we propose that collision and rapid fore-arc rotations play a major role in the evolution and kinematics of back-arc basins. We conduct numerical modeling to better understand the physical processes behind these observed rapid tectonic rotations at convergent margins. Our results suggest that the presence of an indentor or choke point in the subduction system (e.g., collision) can generate rapid rotation of the fore arc about a nearby pole and lead to back-arc rifting. The rate of fore-arc rotation and back-arc rifting depends on the incoming indentor velocity and can be greatly enhanced by slab rollback and the presence of a low-viscosity back arc. Where viscosity of the back arc is low, fore-arc rotation dominates; where back-arc viscosity is high, the formation of strike-slip faults and tectonic escape dominates. Our observational and model-derived results illustrate that shallow crustal forces produced by the entry of buoyant features into subduction zones are a fundamental mechanism for the generation of fore-arc block rotations, plate boundary curvature, back-arc rift evolution, and tectonic escape in subduction systems. Rollback of the subducting slab within the mantle will certainly enhance the processes we describe but it is not the only driving force. Wallace, L. M., S. Ellis, and P. Mann (2009), Collisional model for rapid fore-arc block rotations, arc curvature, and episodic back-arc rifting in subduction settings, Geochem. Geophys. Geosyst., 10, Q05001,

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Section: A22 Present-day Examples Withoutsupporting

confidence: 76%

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

Wallace

Ellis

Mann

2009

Geochem Geophys Geosyst

102

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“…The slope of the middle part of the record indicates a general negative gradient of about 50 nT/km, in contrast to the expected geomagnetic positive gradient. However, this negative gradient agrees with the negative anomaly over the area from surface data (Collot et al, 1985). The model of the anomaly is non-unique and a linear trend was simply removed.…”

Section: Total Magnetic Field Logsupporting

confidence: 59%

Magnetic Logging and In-Situ Magnetostratigraphy: A Field Test

Roperch¹,

Barthés²,

Pocachard³

et al. 1994

Proceedings of the Ocean Drilling Program

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During Ocean Drilling Program Leg 134 (Vanuatu), geological high sensitivity magnetic tools (GHMT) developed by CEA-LETI and TOTAL were used at two drill sites. GHMT combine two sensors, a proton magnetometer for total magnetic field measurements with an operational accuracy of 0.1 nanoteslas (nT), and a highly sensitive induction tool to measure the magnetic susceptibility with an operational accuracy of a few I0" 6 S1 units.Hole 829 A was drilled through an accretionary prism and the downhole measurements of susceptibility correlate well with other well-log physical properties. Sharp susceptibility contrasts between chalk and volcanic silt sediment provide complementary data that help define the lithostratigraphic units.At Hole 83 IB magnetic susceptibility and total field measurements were performed through a 700-m reef carbonate sequence of a guyot deposited on top of an andesitic volcano. The downhole magnetic susceptibility is very low and the amplitude of peak-to-peak anomalies is less than a few 10~5 S1 units. Based on the repeatability of the measurements, the accuracy of the magnetic logging measurements was demonstrated to be excellent. Total magnetic field data at Hole 83IB reveal low magnetic anomalies of 0.5 to 5 nT and the measurement of a complete repeat section indicates an accuracy of 0.1 to 0.2 nT. Due to the inclination of the earth's magnetic field in this area (~-40°) and the very low magnetic susceptibility of the carbonate, the contribution of the induced magnetization to the total field measured in the hole is negligible. Unfortunately, because the core recovery was extremely poor (<5%) no detailed comparison between the core measurements and the downhole magnetic data could be made. Most samples have a diamagnetic susceptibility and very low intensity of remanent magnetization (< I0" 4 A/m), but a few samples have a stable remanent magnetization up to 0.005 A/m. These variations of the intensity of the remanent magnetization suggest a very heterogeneous distribution of the magnetization in the carbonate sequence that could explain the magnetic field anomalies measured in these weakly magnetized rocks.

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“…This is supported by folds in young seafloor sediments east of Maewo and Pentecost, seafloor expression of a possible thrust fault from GLORIA data (Price et al, 1993), and earthquakes having reverse-fault focal mechanisms beneath these islands (Collot et al, 1985;Louat and Pelletier, 1989;Greene et al, this volume). There is no quantitative estimate of the amount of such deformation at the central NHIA.…”

Section: Discussionmentioning

confidence: 85%

“…Migration rates of the DEZ relative to the central NHIA and timing for the resulting tectonic effects, including possible seamount collisions with the arc, should be appropriately increased (e.g., Collot et al, 1985;Collot and Fisher, 1989;Collot and Fisher, 1991;. For example, if the arc trend is 340°, the DEZ is east-west, the convergence direction is 076°, and the A/NHIA convergence rate is 8.8 cm/yr, then the northward migration rate for the DEZ along the arc is 2 cm/yr.…”

Section: Discussionmentioning

confidence: 99%

Quaternary Plate Convergence Rates at the New Hebrides Island Arc from the Chronostratigraphy of Bougainville Guyot (Site 831)

Taylor¹,

Quinn²,

Gallup³

1994

Proceedings of the Ocean Drilling Program

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We have determined convergence rates of the Australia plate with the New Hebrides Island Arc using the chronostratigraphy of Bougainville Guyot, drilled at Site 831, Ocean Drilling Program Leg 134. The convergence rate at the New Hebrides Island Arc is the vectorial sum of convergence rates between the Australia and Pacific plates (8.8 cm/yr at Espiritu Santo Island) and the opening rate of the North Fiji Basin. We assume that the relative motion of the Australia and Pacific plates is unchanging on the 1.5 m.y. time scale and that any changes of rate occurred in the North Fiji Basin. Convergence rates can be calculated because we know the distances at which carbonate sedimentation would cease and resume as the Bougainville Guyot emerged and submerged during its crossing of the outer rise flexure west of the New Hebrides Island Arc. From 1.42 to 0.393 Ma, Bougainville Guyot was subaerially exposed as it moved approximately 177 km across the outer rise and no sediment was deposited. The mean convergence rate during this time interval was 17.2 ± 7 cm/yr, as determined from strontium-isotope and uranium-series ages of the last carbonates before emergence and the first carbonates deposited after submergence. The Australia plate has converged approximately 52 km with the New Hebrides Island Arc at a mean rate of 13.2 ± 1 cm/yr since 0.393 ± .011 Ma when Bougainville Guyot re-submerged and carbonate sedimentation resumed. This age is based on a precise mass-spectrometric Th age measurement and is reliable because the uranium isotopic composition of the sample indicates no diagenetic alteration. The change in convergence rates from 17.2 to 13.2 cm/yr indicates a significant change in the opening rate of the North Fiji Basin. However, this conclusion depends on the age of initial opening of the North Fiji Basin. If the North Fiji Basin began to open at 10 Ma, then the average opening rate at Espiritu Santo Island has been 6 cm/yr. If opening began at 12 Ma, then the average rate had to be 5 cm/yr. Because the relative motion between the Australia and Pacific plates is 8.8 cm/yr, the net convergence rate at the central New Hebrides Island Arc must have averaged 13.8 to 14.8 cm/yr. Younger dates of initial opening would require higher average convergence rates. If the convergence rate of 13.2 cm/yr at Espiritu Santo Island had prevailed for the entire opening of the North Fiji Basin, then the basin would have taken 13-14 m.y. to open at a mean rate of 4.4 cm/yr. This is contrary to hypotheses for the time of origin of the North Fiji Basin.

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Recent tectonics associated with the subduction/ collision of the d'entrecasteaux Zone in the central New Hebrides

Cited by 117 publications

References 26 publications

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

Collisional model for rapid fore‐arc block rotations, arc curvature, and episodic back‐arc rifting in subduction settings

Magnetic Logging and In-Situ Magnetostratigraphy: A Field Test

Quaternary Plate Convergence Rates at the New Hebrides Island Arc from the Chronostratigraphy of Bougainville Guyot (Site 831)

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