relation to Eastern Lau Spreading Centre propagation in the Lau Basin, southwest Pacific

basins west of the axial rift zone of the Eastern Lau Spreading Centre (ELSC), south of the Central Lau Spreading Centre (CLSC). Based on the models of basin evolution, Site 836 is thought to be located on ELSC-generated crust while Site 838 is located on pre-existing extended arc terrain to the west of ELSC-generated crust. Sites 837 and 839 are postulated to be close to the boundary separating ELSC-generated and pre-existing crust. Sediments recovered at all sites comprise late Pliocene to Pleistocene clayey nannofossil ooze containing sparse calcareous turbidites overlying a thick sequence of redeposited volcaniclastic sediments interbedded with hemipelagic clayey nannofossil oozes. All calcareous ooze sections contain hydrothermal ferromanganese oxides. The hydrothermal flux to the sediments at each site has been assessed using non-detrital Mn+Fe accumulation rates for recalculated, hemipelagic sediment intervals alone in order to remove the effect of sediment redeposition. Site 836 shows a typical mid-ocean ridge up-hole pattern of decreasing accumulation rates with increasing crustal accretion, as expected from its predicted location on ELSC-generated crust. Site 837 shows a similar pattern suggesting its location on ELSC-generated rather than pre-existing western Lau Basin attenuated crust. At Sit