Lithology and cement controls on the evolution of compressional wave velocity and porosity in input materials at northern Hikurangi and other subduction zones

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http://abstractsearch.agu.org/meetings/2018/FM/T51I-0309.html
Author(s): Jeppson, Tamara; Kitajima, Hiroko; Ikari, Matt J.; Lee, Hikweon; Ito, Yoshihiro; Harris, Robert N.; Shreedharan, Srisharan; Luo Min; Malie, Pierre R.; Huepers, Andre; Solomon, Evan A.; Underwood, Michael; Kutterolf, Steffen; Meneghini, Francesca; Hashimoto, Yoshitaka; Engelmann de Oliveira, Christie; Rabinowitz, Hannah S.; Noda, Atsushi; Fulton, Patrick M.; 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:
Texas A&M University, Geology and Geophysics, College Station, TX, United States
Other:
University of Bremen, Germany
Korea Institute of Geoscience and Mineral Resources, South Korea
Kyoto University, Japan
Oregon State University, United States
Pennsylvania State University, United States
Shanghai Ocean University, China
Université Montpellier, France
University of Washington, United States
University of Missouri, United States
Helmholtz Centre for Ocean Research Kiel, Germany
University of Pisa, Italy
University of Kochi, Japan
Universidade do Vale do Rio dos Sinos, Brazil
Lamont-Doherty Earth Observatory, United States
National Institute of Advanced Industrial Science and Technology, Japan
University of California-Santa Cruz, 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: The mechanical, physical, and frictional properties of incoming materials play an important role in subduction zone structure and slip behavior because these properties influence the strength of the accretionary wedge and megathrust plate boundary faults. Incoming sediment sections often show an increase in compressional wave speed (Vp) and a decrease in porosity with depth, and follow the velocity-porosity trends expected for consolidated sediments, as described by Erickson and Jarrard (1998). However, consolidation processes are not the only factors influencing the evolution of Vp and porosity. Variations in these properties are also controlled by lithology, composition, cementation, and diagenesis. We present shipboard measurements of Vp and porosity on incoming material cores from Site U1520 of the recent IODP Expedition 375 at the northern Hikurangi margin, where various controls on the evolution of porosity and Vp are observed in different lithologic units. In hemipelagic sediments (Units I-III) and pelagic sediments (Unit IV), porosity generally decreases and Vp increases with depth. In volcaniclastic conglomerates (Unit V), Vp and porosity show a scatter ranging from 1.5-5.0 km/s and 15-60%, with no clear depth-dependent trend. However, the correlation between Vp and porosity is clearly seen for each lithology and well described by empirical relations of Erickson and Jarrad (1998). In volcaniclastic materials, which show various degrees of pore-filling cementation by calcite and zeolite, velocity increases and porosity decreases with increasing CaCO3 content, indicating that the evolution of Vp and porosity is related to the extent of calcite cementation. On the other hand, Vp and porosity in hemipelagic and pelagic units are independent of CaCO3 content, suggesting that the main control on physical properties in these materials is consolidation. We compare data from the Hikurangi margin with data collected during previous IODP expeditions at the Nankai Trough, Aleutian Trench, and Sunda Trench to elucidate the effects of cementation, composition, and lithology on the physical properties of the incoming section and their impacts on the slip behavior of megathrust plate boundary faults.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 18 Geophysics, Solid-Earth; Body waves; Elastic waves; Expedition 375; Hikurangi Margin; Hikurangi Trough; IODP Site U1520; International Ocean Discovery Program; P-waves; Pacific Ocean; Plate tectonics; Seismic waves; South Pacific; Southwest Pacific; Subduction; Subduction zones; West Pacific
Coordinates: S385810 S385810 E1790756 E1790756
Record ID: 2019050440
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