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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https://meetingorganizer.copernicus.org/EGU2019/EGU2019-5534.pdf
Author(s): Gamboa, Davide; Barnes, Phil; Bell, Rebecca; Moore, Greg; 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; de Oliveira, Christie; Pecher, Ingo Andreas; Wallace, Laura M.; Saffer, Demian M.
Author Affiliation(s): Primary:
British Geological Survey, Cardiff, United Kingdom
Other:
National Institute of Water and Atmospheric Research, New Zealand
Imperial College London, United Kingdom
University of Hawaii at Manoa, United States
University of Oxford, United Kingdom
CSIRO, Australia
Ohio State University, United States
National University of Ireland, Ireland
New Mexico Institute of Mining and Technology, United States
Lamont-Doherty Earth Observatory, United States
Japanese Geological Survey, Japan
Universita degli Studi di Pisa, Italy
Christian-Albrechts-Universitat zu Kiel, Germany
Kochi University, Japan
Universidade do Vale do Rio dos Sinos, Brazil
University of Auckland, New Zealand
GNS Science, New Zealand
Pennsylvania State University, United States
Volume Title: European Geosciences Union general assembly 2019
Source: Geophysical Research Abstracts, Vol.21; European Geosciences Union general assembly 2019, Vienna, Austria, April 7-12, 2019. Publisher: Copernicus GmbH on behalf of the European Geosciences Union (EGU), Katlenburg-Lindau, Germany. ISSN: 1029-7006
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. [Copyright Author(s) 2019. CC Attribution 4.0 License: https://creativecommons.org/licenses/by/4.0/legalcode]
Year of Publication: 2019
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 24 Surficial Geology, Quaternary Geology; Australasia; Cenozoic; Cores; Debris flows; Expedition 372; Expedition 375; Geophysical methods; Geophysical surveys; Hikurangi Margin; Hikurangi Trough; IODP Site U1520; International Ocean Discovery Program; Lithostratigraphy; Marine sediments; Mass movements; New Zealand; North Island; Pacific Ocean; Pleistocene; Quaternary; Ruatoria debris flow; Sediments; Seismic methods; Seismic stratigraphy; Slumping; South Pacific; Southwest Pacific; Surveys; Well logs; West Pacific
Coordinates: S385810 S385810 E1790756 E1790756
Record ID: 2019050523
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from European Geosciences Union, Munich, Germany