气候变化领域集成服务门户(CCPortal): The Kefalonia Transform Fault: A STEP fault in the making

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DOI	10.1016/j.tecto.2020.228471
	The Kefalonia Transform Fault: A STEP fault in the making
	Özbakır A.D.; Govers R.; Fichtner A.
发表日期	2020
ISSN	00401951
卷号	787
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
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
语种	英语
来源期刊	Tectonophysics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/207840
作者单位	Department of Earth Sciences, Tectonophysics group, Universiteit Utrecht, Utrecht, Netherlands; Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
推荐引用方式 GB/T 7714	Özbakır A.D.,Govers R.,Fichtner A.. The Kefalonia Transform Fault: A STEP fault in the making[J],2020,787.
APA	Özbakır A.D.,Govers R.,&Fichtner A..(2020).The Kefalonia Transform Fault: A STEP fault in the making.Tectonophysics,787.
MLA	Özbakır A.D.,et al."The Kefalonia Transform Fault: A STEP fault in the making".Tectonophysics 787(2020).