Chapter 59 - Geomorphology and benthic habitats of the Kermadec Trench, Southwest Pacific Ocean

Abstract

The Kermadec Trench, located in the southwestern Pacific Ocean, is ~1195km long, 120km wide, ~10,000m deep, and accounts for 3.6% of the New Zealand Exclusive Economic Zone. Formed by the subduction of the Pacific Plate under the Australian Plate, the trench exhibits steep adjacent slopes, that, north of 32°S on the underriding plate, can exceed 40 degrees due to an extensive network of fault escarpments up to 1000m in height and that are laterally extensive over many tens of kilometers. General oceanographic conditions and the characteristics of the fault escarpments, the deep trench axis, and the north (Osborn Seamount) and south (Hikurangi Trough and Rapuhia Scarp intersection) boundaries of the trench habitat are discussed. There is evidence of mass flow deposits, petite spot volcanism, and sedimentary basins that form complex habitats for benthic fauna. Overall data for biological communities that can be statistically compared are limited, but patterns in the distribution of selected hadal communities are described.