Clayey nannofossil ooze turbidites and hemipelagites at sites 834 and 835 (Lau Basin, southwest Pacific)

Abstract

The western Lau Basin contains several small elongate, fault-bounded, partiallt sediment-filled sub-basins. Sites 834 and 835 were drilled in the oldest part of the Lau Basin in two of these small extensional basins close to the Lau Ridge, formed on late Miocene to early Pliocene oceanic crust. Both sites show a similar sediment sequence that consists of clayey nannofossil oozes and mixed sediments interbedded with epiclastic vitric sands and silts. The sediment sequence at Site 835 is dominated by allochthonous sediments. The adjacent high ground was affected by marked instability throughout the late Pliocene and Pleistocene. In contrast, sedimentation at Site 835 during this period has been dominated by hemipelagic deposition, with redeposited sediments making up slightly less than 17% of the total thickness of sediment deposited since 2.3 Ma. -from Authors