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Crustal structure of the Ontong Java Plateau: modeling of new gravity and existing seismic data


Gladczenko, TP and Coffin, MF and Eldholm, O, Crustal structure of the Ontong Java Plateau: modeling of new gravity and existing seismic data, Journal of Geophysical Research, 102, (B10) pp. 22711-22729. ISSN 0148-0227 (1997) [Refereed Article]

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Copyright 1997 American Geophysical Union

DOI: doi:10.1029/97JB01636


Seismic refraction and gravity-based crustal thickness estimates of the Ontong Java oceanic plateau, the Earth's largest igneous province, differ by as much as 18 km. In an attempt to reconcile this difference we have evaluated available seismic velocity data and developed a layered crustal model which includes (1) a linear increase in velocity with depth in the Cenozoic sediments and the uppermost extrusive basement and (2) a reinterpretation of deep crustal and Moho arrivals in some deep refraction profiles. Previously, Moho had commonly been interpreted from later arrivals and in some cases constrained by precritical arrivals. However, if first arrivals at distal offsets are interpreted as Moho refractions, the maximum depth to Moho is reduced by about 10 km. Two-dimensional gravity modeling along two transects from well-determined oceanic crust in the Nauru Basin across the central On-tong Java Plateau to the Lyra Basin, based on the reinterpreted crustal model, is regionally consistent with satellite altimetry derived and shipboard gravity fields yielding a 8.0 km/s Moho velocity at a depth of 32 km under the central plateau. The crust features a thick oceanic, three-layer igneous crust comprising an extrusive upper crust, a 6.1 km/s middle crust and a 15 km thick 7.1 km/s lower crust. The total Ontong Java Plateau crustal volume is calculated at 44.4 106 km3 and 56.7 106 km3 for off- and on-ridge emplacement settings, respectively. On the basis of velocities and densities we interpret the lower crust on the plateau to consist of ponded and fractionated primary picritic melts, which due to deformation and/or fluid invasion may have recrystallized to granulite facies mineral assemblages. The melts were emplaced during lithospheric breakthrough of a mantle plume in an oceanic, near-ridge plate tectonic setting.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Marine geoscience
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Coffin, MF (Professor Mike Coffin)
ID Code:73770
Year Published:1997
Web of Science® Times Cited:103
Deposited By:Research Division
Deposited On:2011-10-25
Last Modified:2012-03-22
Downloads:1 View Download Statistics

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