Constraining the deformation history of the frontal wedge of Hikurangi subduction margin with analog modeling and bedding trends from borehole logging of IODP Expedition 372

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Author(s): Koge, Hiroaki; McNamara, David D.; Gamboa, Davide; Wu, Hung-Yu; Kim, Gil Young; Cardona, Sebastian; Shanker, Uma; Barnes, Philip; Pecher, Ingo Andreas; LeVay, Leah J.; Saffer, Demian M.; Wallace, Laura M.; Petronotis, Katerina E.; Noda, Atsushi; Morgan, Julia; Ashi, Juichiro; Yamaguchi, Asuka; Yamada, Yasuhiro; Hamada, Yohei
International Ocean Discovery Program (IODP), Expedition 372 Scientists
Author Affiliation(s): Primary:
University of Tokyo, Atmosphere and Ocean Research Institute, Tokyo, Japan
GNS Science, New Zealand
British Geological Survey, United Kingdom
Japan Agency for Marine-Earth Science and Technology, Japan
Korea Institute of Geoscience and Mineral Resources (KIGAM), South Korea
Colorado School of Mines, United States
Banaras Hindu University, India
National Institute of Water & Atmospheric Research, New Zealand
University of Auckland, New Zealand
Integrated Ocean Drilling Program, United States
Pennsylvania State University, United States
University of Texas at Austin, United States
International Ocean Discovery Program, United States
National Institute of Advanced Industrial Science and Technology, Japan
Rice University, United States
University of Tokyo, Japan
Kyoto University, Japan
Kochi Institute for Core Sample Research, Japan
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: IODP Expeditions 372/375 were conducted at the Hikurangi Subduction Margin (HSM) off the eastern North Island, New Zealand, to investigate slow slip earthquakes (SSEs). At site U1518 a thrust fault in the frontal wedge was drilled in the region of at the deformation front of the subduction margin. This area of the frontal wedge includes the shallowest part of the plate boundary and experiences shallow SSEs. In addition, fault rupture propagation in the region has tsunamigenic potential to generate events such as the 2011 earthquake in Japan. Thus, it is important to consider the kinematics of how this frontal wedge was formed and subsequently deforms. Analysis of bedding orientations defined using logging-while-drilling (LWD) resistivity imaging during Exp.372 shows that the hanging wall sediments at site U1518 have NE dip directions, except for the interval 170.5-229.5 mbsf where bedding dips SW and a number of conductive and resistive fractures are observed. In addition, the bedding trends of Exp. 375 core-result agrees well with the trends from the of Exp. 372 LWD resistivity images. We hypothesize that the thrust fault and associated folding in the hanging wall are related to seamount subduction and employ analog model experiments with the Digital Image Correlation (DIC) to test. DIC is the technique to visualize the fault activity in analog modeling. The experimental setup consists of a box of 25×90×30 cm with a moving wall, side-glass panes, and a Teflon-surfaced basement. The seamount model was set 55 cm from the model walls. For experiments, the initial sand thickness was 2 cm and color layers are installed inside to visualize and trace the development of bedding orientations and internal structure. Preliminary results show a rapidly growing the surface slope with the subduction of the seamount, followed by slope failure activating in the most frontal portion. The slope growth became active after the seamount passes through the front. The slope failure resulted in a mass transport deposit onto the footwall and consequently subducted. The position of this subducted deposits was just below the fore thrust with thick transported deposition. In addition, the development of a piggyback basin was observed. The change of bedding dip within the piggyback basin shows the similar trends to the bedding estimated using LWD data.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 18 Geophysics, Solid-Earth; Crust; Deformation; Expedition 372; Hikurangi Margin; IODP Site U1518; Integrated Ocean Drilling Program; International Ocean Discovery Program; Lithosphere; Oceanic crust; Oceanic lithosphere; Pacific Ocean; Plate tectonics; South Pacific; Southwest Pacific; Subduction; Subduction zones; West Pacific
Coordinates: S385133 S385133 E1785346 E1785346
Record ID: 2019050433
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