DOI: 10.1016/j.tecto.2020.228471
论文题名: The Kefalonia Transform Fault: A STEP fault in the making
作者: Özbakır A.D. ; Govers R. ; Fichtner A.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2020
卷: 787 语种: 英语
中文关键词: Hellenic Subduction Zone
; Slab segmentation
; STEPs
; Subduction zone processes
; Tomography
英文关键词: Deformation
; Plates (structural components)
; Strike-slip faults
; Structural geology
; Velocity
; Convergence velocity
; Full-waveform inversion
; Hellenic subduction zone
; Lithosphere-mantle interactions
; Lithospheric mantle
; Strike-slip deformation
; Subduction-transform edge propagator
; Upper mantle structure
; Transform faults
; continental crust
; crustal structure
; fault zone
; mantle structure
; plate convergence
; seismicity
; subduction zone
; transform fault
; trench
英文摘要: Vertical edges along subducted slabs have been recognized in the majority of subduction zones. Surprisingly, slab edges evolved into Subduction-Transform-Edge-Propagator (STEP) faults in only a few regions; the conditions under which STEPs form are special. It is relevant to constrain the conditions that facilitate STEP fault initiation because they leave a clear geological footprint in the overriding plate, whereas vertical tears generally do not. We therefore study a candidate region for STEP fault initiation in the western Hellenic Subduction Zone. We investigate the structure and seismicity of the shallow western Hellenic Subduction Zone using a recent full-waveform inversion model which both captures details of crustal and upper-mantle structure, yielding constraints in the depth interval from 10 to 200 km where lithosphere-mantle interactions have tectonic expressions. The western end of the Hellenic Subduction Zone is fragmented near the Kefalonia Transform Fault. We identify a separate Epirus lithospheric fragment that is roughly vertical below the southern Albanides. We also identify a new and major contrast within the lithospheric mantle of the Ionian ocean basin, which aligns with a gradient in free-air anomalies. In the overriding plate, the Kefalonia Transform Fault zone accommodates right lateral strike-slip deformation. We interpret this fault zone as a proto-STEP fault that formed simultaneously with Pliocene fragmentation of the Epirus fragment. Comparing the recent evolution of the NW Hellenic slab edge with currently active STEPs indicates that along-trench variations in convergence velocity are a prerequisite for STEP fault initiation. Such velocity variations may result from subduction of continental crust along part of the trench. Resistance to sea ward tear propagation by a mechanically strong subducting plate may prevent variations in convergence velocity to occur, and thus STEP fault initiation. The amount of time over which a velocity contrast persists will also be relevant for STEP fault initiation. Mechanical coupling between upper- and lower-plate, and the deformability of the upper-plate appear to also play a role in the initiation of the STEP fault once a slab is fragmented. © 2020 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170673
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth Sciences, Tectonophysics group, Universiteit Utrecht, Utrecht, Netherlands; Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
Recommended Citation:
Özbakır A.D.,Govers R.,Fichtner A.. The Kefalonia Transform Fault: A STEP fault in the making[J]. Tectonophysics,2020-01-01,787