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

journal contribution
posted on 2023-05-17, 08:37 authored by Ingle, S, Mahoney, JJ, Sato, H, Mike CoffinMike Coffin, Kimura, JI, Hirano, N, Nakanishi, M
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 ¡¾ 3.5 Ma (2¥ò), 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 ¡¾ 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.

History

Publication title

Geology (Boulder)

Volume

35

Issue

7

Pagination

595-598

ISSN

0091-7613

Department/School

Institute for Marine and Antarctic Studies

Publisher

Geological Soc America

Place of publication

Inc, Po Box 9140, Boulder, USA, Co, 80301-9140

Rights statement

Copyright © 2007 Geological Society of America

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

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