DOI: 10.1016/j.tecto.2019.228275
论文题名: Implications of basement rock alteration in the Nankai Trough, Japan for subduction megathrust slip behavior
作者: Ikari M.J. ; Wilckens F.K. ; Saffer D.M.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2020
卷: 774 语种: 英语
中文关键词: Basalt
; Earthquake
; Nankai Trough
; Oceanic basement
; Slow slip
; Subduction
英文关键词: Basalt
; Buildings
; Earthquakes
; Friction
; Shearing
; Velocity
; Friction experiments
; Frictional behavior
; Megathrust earthquakes
; Nankai troughs
; Oceanic basement
; Seismic reflections
; Slow slip
; Subduction
; Fault slips
; basalt
; basement rock
; chemical alteration
; earthquake
; friction
; slip rate
; subduction
; thrust
; Nankai Trough
; Pacific Ocean
英文摘要: The Nankai Trough is an exceptionally well-studied convergent margin known to host damaging megathrust earthquakes as well as various forms of slow fault slip. Outcrop studies of exhumed analogues for the modern subduction thrust, as well as seismic reflection images of the active subduction zone, suggest that the basaltic basement participates in plate-boundary shearing at depths of a few km and greater. We obtained altered basaltic upper basement from the modern Nankai Trough seaward of the trench, recovered by drilling on IODP Expedition 333. We performed laboratory friction experiments on bare surfaces and gouge powders of this material, in addition to and in combination with other materials for comparison. The altered basalt exhibits predominantly velocity-strengthening frictional behavior, indicating a tendency for stable slip. For bare surface experiments, few instances of velocity-weakening friction occur and are restricted to slip rates of <10− 6 m/s. Thin sections and XRD analyses of the starting material indicate that the velocity-strengthening behavior is likely associated with the presence of clay minerals, mostly Mg-smectite, which coat the rims of larger, stronger grains. Based our friction data, we suggest that in addition to creep the altered Nankai basalts may also allow the possibility of slow slip events for two reasons: (1) velocity-weakening friction may be expected at low slip rates, but velocity-strengthening at higher rates will damp any potential slip instabilities; and (2) based on a critical stiffness criterion for accelerating (stable) slip, SSEs are capable of nucleating in the altered Nankai basalt despite velocity-strengthening friction. In light of these observations, and given the depth at which altered basement appears to be incorporated along the plate interface, we raise the possibility that some shallow slow slip events in the Nankai accretionary prism could originate from shearing in altered basalt. © 2019 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170611
Appears in Collections: 气候变化与战略
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作者单位: MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen, D-28359, Germany; Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, United States; Faculty of Geosciences, University of Bremen, Bremen, D-28359, Germany; Center for Geomechanics, Geofluids, and Geohazards, The Pennsylvania State University, University Park, PA 16802, United States
Recommended Citation:
Ikari M.J.,Wilckens F.K.,Saffer D.M.. Implications of basement rock alteration in the Nankai Trough, Japan for subduction megathrust slip behavior[J]. Tectonophysics,2020-01-01,774