Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ingle, S. Articles by Nakanishi, M. Search for Related Content GeoRef GeoRef Citation

Depleted mantle wedge and sediment fingerprint in unusual basalts from the Manihiki Plateau, central Pacific Ocean

¹ Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
² School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, Hawaii 96822, USA
³ School of Business Administration, Senshu University, Kanagawa 214-8580, Japan
⁴ Ocean Research Institute, University of Tokyo, Tokyo 164-8639, Japan
⁵ Department of Geoscience, Shimane University, Matsue 690-8504, Japan
⁶ Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
⁷ Graduate School of Science and Technology, Chiba University, Chiba 263-8522, Japan

Numerous large igneous provinces formed in the Pacific Ocean during Early Cretaceous time, but their origins and relations are poorly understood. We present new geochronological and geochemical data on rocks from the Manihiki Plateau and compare these results to those for other Cretaceous Pacific plateaus. A dredged Manihiki basalt gives an ⁴⁰Ar-³⁹Ar age of 117.9 ± 3.5 Ma (2), essentially contemporaneous with the Ontong Java Plateau 2500 km to the west, and the possibly related Hikurangi Plateau 3000 km to the south. Drilled Manihiki lavas are tholeiitic with incompatible trace element abundances similar to those of Ontong Java basalts. These lavas may result from high degrees of partial melting during the main eruptive phase of plateau formation. There are two categories of dredged lavas from the Danger Islands Troughs, which bisect the plateau. The first is alkalic lavas having strong enrichments in light rare earth and large-ion lithophile elements; these lavas may represent late-stage activity, as one sample yields an ⁴⁰Ar-³⁹Ar age of 99.5 ± 0.7 Ma. The second category consists of tholeiitic basalts with U-shaped incompatible element patterns and unusually low abundances of several elements; these basalts record a mantle component not previously observed in Manihiki, Ontong Java, or Hikurangi lavas. Their trace element characteristics may result from extensive melting of depleted mantle wedge material mixed with small amounts of volcaniclastic sediment. We are unaware of comparable basalts elsewhere.

Key Words: large igneous provinces • Early Cretaceous • Manihiki Plateau • Pacific Ocean • geochemistry • geochronology