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GEOREF RECORD

Jurassic oceanic lithosphere beneath the southern Ontong Java Plateau; evidence from xenoliths in alnoeite, Malaita, Solomon Islands

Akira Ishikawa, Eizo Nakamura and John J. Mahoney
Jurassic oceanic lithosphere beneath the southern Ontong Java Plateau; evidence from xenoliths in alnoeite, Malaita, Solomon Islands
Geology (Boulder) (May 2005) 33 (5): 393-396

Abstract

The least metasomatized xenoliths of spinel lherzolite and gabbro recovered from alnoite intruding crust of the southern Ontong Java Plateau on the island of Malaita yield an Sm-Nd age of ca. 160 Ma and an initial epsilon (sub Nd) value of approximately +8. In contrast, the plateau basement is ca. 120 Ma with initial epsilon (sub Nd) between +3.7 and +6.5. The xenoliths appear to represent normal Pacific oceanic lithosphere (uppermost mantle and lower crust) formed approximately 40 m.y. before the plateau, indicating that the southern part of the plateau was emplaced off axis on mature seafloor. The closest 160 Ma seafloor to Malaita is >1800 km to the north, off the northeastern margin of the plateau, implying the presence of either an intervening large-offset fracture zone or a triple junction. The presence of significantly older oceanic lithosphere beneath the plateau places restrictions on proposed origins for the plateau.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 33
Serial Issue: 5
Title: Jurassic oceanic lithosphere beneath the southern Ontong Java Plateau; evidence from xenoliths in alnoeite, Malaita, Solomon Islands
Affiliation: Okayama University at Misasa, Pheasant Memorial Laboratory, Tottori, Japan
Pages: 393-396
Published: 200505
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 33
Accession Number: 2005-034356
Categories: Solid-earth geophysicsGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2005071
Illustration Description: illus. incl. sketch map
S11°00'00" - S10°00'00", E160°00'00" - E162°00'00"
Secondary Affiliation: University of Hawai'i, School of Ocean and Earth Science and Technology, Honolulu, Hawaii 96822, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200519
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