(Table DR1) Trace element contents in basalts from ODP Hole 33-317A

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 sigma), 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.

Planktonic foraminifers in DSDP Holes 30-289 and 33-315A

The work is based on samples from Deep-Sea Drilling in the Pacific Ocean and from natural sections in its continental setting. Species composition of planktonic foraminifera from Maastrichtian sediments of the Pacific and South Atlantic oceans, as well as from marginal seas of Australia and New Zealand and epicontinental basins of the northern hemisphere has been analysed. Two main issues: reconstruction of Maastrichtian climatic zonality, and reconstruction of Maastrichtian paleodepths. Four bipolar climatic zones have been distinguished. According to preservation of planktonic foraminifera and composition of their complexes three levels of dissolution have been identified.