DOI: 10.1016/j.epsl.2019.115935
论文题名: High- and low-stress subduction zones recognized in the rock record
作者: Ishii K. ; Wallis S.R.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 531 语种: 英语
中文关键词: Franciscan belt
; metamorphic P–T paths
; numerical model
; Sanbagawa belt
; shear stress
; subduction boundary
英文关键词: Friction
; Heating
; Lithology
; Metamorphic rocks
; Numerical models
; Shear stress
; Uncertainty analysis
; Coefficient of frictions
; Convergent margin
; Frictional shear
; Metamorphic belts
; Subducting slabs
; subduction boundary
; Subduction rates
; Subduction zones
; Shear flow
; boundary layer
; heat flow
; metamorphic rock
; numerical model
; P-T conditions
; record
; shear stress
; subduction zone
; Japan
; Sambagawa Belt
; United States
; Calluna vulgaris
英文摘要: It is generally accepted that the main strength of subduction boundaries occurs in the shallower region where frictional deformation is dominant. However, estimates of absolute values—commonly expressed as apparent coefficient of friction, μ′—show great variation. Frictional shear heating is closely related to μ′, and estimates of the extra thermal energy supplied by shearing can in principle be used to estimate subduction zone strength. One such approach is based on surface heat flow measurements. However, heat flow in convergent margins shows large local scatter and even in the same area, different studies using this method show large variations in estimates of μ′ indicating large uncertainties. The thermal record of subduction conditions preserved in subduction-type metamorphic rocks is developed over geological time scales that average out local complexities in heat flow and therefore has good potential as an alternative indicator of the amount of shear heating and, hence, shear strength along subduction boundaries. Thermal models that incorporate shear heating were developed for two contrasting and well-known subduction-type metamorphic belts: the relatively warm Sanbagawa belt of SW Japan and the relatively cold Franciscan belt of western USA. High-grade rocks of the Sanbagawa belt show strongly curved P–T paths that display increasing P/T to about 2 GPa. Information on the rate of plate movement and the age of the subducting slab at the time of metamorphism can be combined with modelling results to show that relatively high shear stresses, equivalent to μ′∼0.13 are required to account for the observed curved P–T paths. In contrast, the high-grade rocks of the Franciscan belt show relatively cool P–T conditions that do not allow for strong shear heating with an appropriate upper bound for μ′ of ∼0.03. Modelling suggests subduction rate and lithology are potentially important controls on the development of high- versus low-stress subduction zones. High-stress subduction zones are likely to be associated with high aseismic/seismic slip ratios possibly related to slab roughness. © 2019 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165049
Appears in Collections: 气候变化与战略
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作者单位: Department of Physical Science, Graduate School of Sciences, Osaka Prefecture University, Sakai, Osaka, Japan; Department of Earth and Planetary Science, Faculty of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
Recommended Citation:
Ishii K.,Wallis S.R.. High- and low-stress subduction zones recognized in the rock record[J]. Earth and Planetary Science Letters,2020-01-01,531