Revisiting the giant Ruatoria debris flow on the Hikurangi Margin, New Zealand; results from IODP Expeditions 372 and 375, Site U1520

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Author(s): Barnes, Philip; Gamboa, Davide; Bell, Rebecca E.; Moore, Gregory F.; Mountjoy, Joshu J.; Paganoni, Matteo; Clennell, Michael Ben; Cook, Ann; McNamara, David D.; Underwood, Michael; Rabinowitz, Hannah S.; Noda, Atsushi; Meneghini, Francesca; Kutterolf, Steffen; Hashimoto, Yoshitaka; Engelmann de Oliveira, Christie; Pecher, Ingo Andreas; Wallace, Laura M.; Saffer, Demian M.; LeVay, Leah J.; Petronotis, Katerina E.
International Ocean Discovery Program (IODP), Expedition 372 Scientists
Author Affiliation(s): Primary:
National Institute of Water & Atmospheric Research, Wellington, New Zealand
British Geological Survey, United Kingdom
Imperial College London, United Kingdom
University of Hawaii at Manoa, United States
National Institute of Water and Atmospheric Research, New Zealand
Shell Global Solutions International, Netherlands
CSIRO Earth Science Resource Engineering, Australia
Ohio State University, United States
GNS Science, New Zealand
University of Missouri, United States
Lamont-Doherty Earth Observatory, 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
University of Auckland, New Zealand
University of Texas at Austin, United States
Pennsylvania State University, United States
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: Submarine landslides are recurrent features along the Hikurangi Subduction Margin, offshore New Zealand, occurring in high numbers within depositional forearc basins and the subduction trough. The sedimentary sequences of the Hikurangi Trough located between the deformation front and Turanganui Knoll were drilled for the first time at Site U1520 during IODP Expeditions 372 and 375. This drill site intersected the toe domain of the giant Ruatoria Debris Flow (RDF). Despite being one of the largest submarine avalanches yet identified on Earth, the RDF is drastically understudied and many outstanding questions regarding its morphology, internal composition and complexity, and emplacement mechanisms are still unanswered. Here we integrate observations from 2D seismic profiles, Logging-while-drilling (LWD) data acquired during Expedition 372 and sediment cores retrieved during Expedition 375 for a preliminary characterisation of the RDF. The RDF is seismically distinct from the bounding seismic units at Site U1520, showing low to moderate amplitudes. Internal reflections vary from chaotic to stratified in places. Intra-RDF imbricated thrusts are observed on seismic data, especially on the western edge. Synthetic logs show a good correlation between seismic and logging units. LWD data indicates that the top of the RDF is at 107 mbsf and the base at 225 mbsf. Sediment cores retrieved from Site U1520 indicate approximate values for the top of the RDF, intersecting it at 110 mbsf, but the base was not sampled. Although the RDF log signature is well delimited and distinct from the adjacent logging units, lithofacies analysis from cores do not show marked changes from overlying turbidite units. This suggests Site U1520 intersected the RDF at a rafted block with no deformation. Future work aims to characterise the dynamics and local vs distant sources of sediment remobilised by the Ruatoria Debris Flow.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 23 Surficial Geology, Geomorphology; Debris flows; Expedition 372; Expedition 375; Geophysical methods; Geophysical profiles; Geophysical surveys; Hikurangi Margin; Hikurangi Trough; IODP Site U1520; International Ocean Discovery Program; Landslides; Mass movements; Pacific Ocean; Seismic methods; Seismic profiles; South Pacific; Southwest Pacific; Surveys; West Pacific
Coordinates: S385810 S385810 E1790756 E1790756
Record ID: 2019050441
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