DOI: 10.1016/j.epsl.2020.116490
论文题名: Record of intermediate-depth subduction seismicity in a dry slab from an exhumed ophiolite
作者: Pennacchioni G. ; Scambelluri M. ; Bestmann M. ; Notini L. ; Nimis P. ; Plümper O. ; Faccenda M. ; Nestola F.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 548 语种: 英语
中文关键词: earthquake
; eclogite
; fluids
; ophiolite
; pseudotachylyte
; subduction
英文关键词: Deformation
; Glass
; Hydration
; Kaolinite
; Reaction kinetics
; Serpentine
; Brittle ductile transitions
; Dehydration embrittlements
; Ductile deformations
; Intermediate depths
; Oceanic lithosphere
; Pseudotachylytes
; Rheological behaviour
; Temperature range
; Earthquakes
; antigorite
; earthquake trigger
; exhumation
; gabbro
; ophiolite
; peridotite
; seismicity
; slab
; subduction
; Alps
; Western Alps
英文摘要: The ophiolitic peridotite and gabbro of Moncuni (Southern Lanzo Massif, Western Alps) retain pre-subduction mantle-to-oceanic, high-temperature (>700C∘) ductile fabrics. These fabrics are overprinted by seismic fracturing and faulting associated with pseudotachylytes. Within the gabbro, the pseudotachylytes preserve dry glass and pristine microlites. The occurrence of rare, minute garnet and the static development of eclogite-facies assemblages in local hydrated domains indicate that pseudotachylytes experienced subduction conditions of 600C∘ and 2.1 GPa. The exceptional survival of glass and the absence of post-oceanic ductile deformation demonstrate prevailing dry conditions during the entire Alpine subduction and exhumation path. Dry conditions inhibited reaction kinetics and viscous flow. In contrast, the majority of the Alpine ophiolites, derived from the upper hydrated portions of the oceanic lithosphere, show pervasive fluid-assisted metamorphism and ductile deformation. The Moncuni body can, therefore, be regarded as representative for the rheological behaviour during subduction of seismic, dry, deeper oceanic lithosphere that is rarely exhumed to the Earth's surface. In Moncuni, the brittle-ductile transition of dry oceanic rocks is constrained to be between 600 and 750C∘. This temperature range corresponds to the observed cut-off of intermediate-depth seismicity within subducting slabs. We infer that the base of the seismic layer corresponds to the brittle-ductile transition of a dry slab rather than the locus of antigorite breakdown triggering earthquakes by dehydration embrittlement. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165206
Appears in Collections: 气候变化与战略
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作者单位: Dipartimento di Geoscienze, Università di Padova, Via G. Gradenigo 6, Padova, 35131, Italy; Dipartimento di Scienze della Terra, Ambiente e Vita, University of Genova, Corso Europa 26, Genova, 16132, Italy; GeoZentrum Nordbayern, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany; Department of Earth Sciences, Utrecht University, Netherlands
Recommended Citation:
Pennacchioni G.,Scambelluri M.,Bestmann M.,et al. Record of intermediate-depth subduction seismicity in a dry slab from an exhumed ophiolite[J]. Earth and Planetary Science Letters,2020-01-01,548