Early Pliocene landward submarine slumping, Lachlan Basin, Hawke Bay, New Zealand

Abstract

Early Pliocene slumping is identified in a seismic profile that traverses offshore Lachlan Basin in Hawke Bay, eastern North Island. The slump is identified by a package of chaotic discontinuous reflections that overlies a basal Pliocene unconformity and is bounded above, laterally, and below by coherent, continuous reflections. It is upwards of 0.25 s thick (c. 200 m) and has a profile extent of c. 12 km. The slump was generated from the western flank of Lachlan Ridge, a thrust‐cored structure that was actively growing at this time. Mass transport of sediment was landward, opposite that for the younger Kidnappers Slide and other major slope failure complexes in the region.

Keywords:

• Lachlan Basin
• Hawke Bay
• growing anticline
• accretionary prism
• slope failure
• slumping
• seismic stratigraphy
• Pliocene