Lithostratigraphy of the hikurangi subduction inputs; results of coring during IODP Expedition 375

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Author(s): Underwood, Michael; Rabinowitz, Hannah S.; Noda, Atsushi; Meneghini, Francesca; Kutterolf, Steffen; Hashimoto, Yoshitaka; Engelmann de Oliveira, Christie; Saffer, Demian M.; Wallace, Laura M.; Barnes, Philip; Pecher, Ingo Andreas; Petronotis, Katerina E.; LeVay, Leah J.
International Ocean Discovery Program (IODP), Expedition 372 Scientists
Author Affiliation(s): Primary:
New Mexico Institute of Mining and Technology, Earth and Environmental Sciences, Socorro, NM, United States
Brown University, United States
National Institute of Advanced Industrial Science and Technology, Japan
University of Pisa, Italy
Helmholtz Centre for Ocean Research Kiel, Germany
University of Kochi, Japan
Universidade do Vale do Rio dos Sinos, Brazil
Pennsylvania State University, United States
GNS Science, New Zealand
National Institute of Water & Atmospheric Research, New Zealand
University of Auckland, New Zealand
International Ocean Discovery Program, United States
Volume Title: AGU 2018 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2018; American Geophysical Union 2018 fall meeting, Washington, DC, Dec. 10-14, 2018. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Expedition 375 of the International Ocean Discovery Program provided ground truth for core-log-seismic integration at four sites along the Hikurangi subduction system offshore the North Island, New Zealand. The primary objectives at Sites U1520 and U1526 were to sample the subduction inputs and document their potential influence on shallow slow-slip events (SSE) documented on the plate interface within the drilling transect. Site U1520 is located near the seaward edge of the Hikurangi Trough at a water depth of 3520 m. The stratigraphic succession there consists of: (a) a basal unit that contains a disjointed blend of rock types whose primary stratigraphic organization is unresolved; (b) 168 m of volcaniclastic sediments that were deposited during the Late Cretaceous along the NW flank of the Hikurangi Plateau, a large igneous province on the subducting Pacific plate; (c) Paleocene-Pliocene pelagic carbonates, 338 m thick, composed of calcareous mudstone, marl, chalk, and scattered debris-flow deposits; (d) a 112-m-thick slab of turbidites and hemipelagic mud, internally intact, that was evidently displaced toward the SW as part of the Ruatoria debris avalanche; and (e) the Quaternary trench-wedge, sandwiched above and below the slide block and composed mostly of terrigenous turbidites (silt to fine sand) interbedded with hemipelagic mud. Pervasive alteration products within the volcaniclastics include highly variable amounts of clay minerals (smectite), zeolites (phillipsite, clinoptilolite/heulandite), calcite, and silica. The granule-size clasts were probably deposited by debris flows and grain flows. Site U1526 is located 2908 m below SL near the crest of a small seamount. Deposits there consist of a hemipelagic to pelagic carapace above less-altered and coarser-grained volcaniclasts (gravel-size to boulder-size, subrounded to subangular). The subducting Hikurangi Plateau records a history of basalt eruption, fragmentation, clast abrasion, frequent remobilization by sediment-gravity flow, subsidence from a setting that was initially subaerial to shallow-marine, and burial beneath the trench wedge. Alteration of the volcaniclastic strata, prior to and during subduction, probably modulates the key frictional and elastic properties and fluid content within the SSE source region.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 18 Geophysics, Solid-Earth; Expedition 375; Hikurangi Margin; Hikurangi Trough; IODP Site U1520; IODP Site U1526; International Ocean Discovery Program; Lithostratigraphy; Pacific Ocean; Plate tectonics; South Pacific; Southwest Pacific; Subduction; Subduction zones; Tectonics; West Pacific
Coordinates: S385810 S385810 E1790756 E1790756
S390119 S390119 E1791445 E1791445
Record ID: 2019050438
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States