Evidence for late Eocene emplacement of the Malaita Terrane, Solomon Islands; implications for an even larger Ontong Java Nui oceanic plateau

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doi: 10.1002/jgrb.50153
Author(s): Musgrave, Robert J.
Author Affiliation(s): Primary:
Geological Survey of New South Wales, Maitland, N.S.W., Australia
Volume Title: Journal of Geophysical Research: Solid Earth
Source: Journal of Geophysical Research: Solid Earth, 118(6), p.2670-2686. Publisher: Wiley-Blackwell for American Geophysical Union, Washington, DC, United States. ISSN: 2169-9313
Note: In English. 95 refs.; illus., incl. 3 tables, geol. sketch maps
Summary: Most tectonic models for the Solomon Islands Arc invoke a Miocene collision with the Ontong Java Plateau (OJP) to halt cessation of Pacific Plate subduction, initiate Australian Plate subduction, and emplace the Malaita Terrane, which shares the characteristic basement age and geochemistry of OJP. Existing paleomagnetic evidence, however, required the Malaita Terrane to have been fixed to the arc from at least the Late Eocene. New sampling has yielded a paleomagnetic pole from Aptian-Albian limestones and mudstones that falls between the apparent polar wander paths for the Australian Plate and OJP, confirming the extended period of residence of the Malaita Terrane on the arc. Arc-derived turbidities within Late Eocene through Miocene limestones on Malaita and Santa Isabel, and related clasts in broadly contemporary sandstones and conglomerates on Santa Isabel, also attest to early emplacement. Modeling the emplacement at 35 Ma satisfies both the paleomagnetic data and the sediment provenance. Continuing the reconstruction to 125 Ma leaves the Malaita Terrane far from OJP at the time of plateau formation. OJP is now understood to have formed as part of a larger Ontong Java Nui, also comprising the Hikurangi and Manihiki plateaus, separated by spreading during the Cretaceous. Restoring the separation of the known elements, and invoking an additional triple junction, unites the (now largely subducted) Malaita Terrane with the rest of Ontong Java Nui. Subduction of substantial areas of the Ontong Java Nui plateau, with little geological signal other than a reduction in arc volcanism, is a corollary. Abstract Copyright (2013), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2013
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; Albian; Aptian; Australian Plate; Carbonate rocks; Cenozoic; Chalk; Characteristic remanent magnetization; Cretaceous; Demagnetization; East Pacific; Eocene; Equatorial Pacific; Hikurangi Trough; Hysteresis; Integrated Ocean Drilling Program; Leg 130; Limestone; Lower Cretaceous; Magnetic inclination; Magnetic properties; Magnetic susceptibility; Magnetization; Malaita Terrane; Manihiki Plateau; Melanesia; Mesozoic; Miocene; Models; Neogene; North Pacific; Northwest Pacific; ODP Site 807; Ocean Drilling Program; Oceania; Ontong Java Plateau; Overprinting; Pacific Ocean; Pacific Plate; Paleogene; Paleomagnetism; Plate tectonics; Polar wandering; Pole positions; Reconstruction; Remanent magnetization; Sampling; Sea-floor spreading; Sedimentary rocks; Solomon Islands; South Pacific; Southeast Pacific; Southwest Pacific; Subduction; Tertiary; Upper Cretaceous; Upper Eocene; West Pacific
Coordinates: N033622 N033626 E1563730 E1563728
Record ID: 2017042362
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom