气候变化领域集成服务门户(CCPortal): Blueschist-facies paleo-earthquakes in a serpentinite channel (Zagros suture, Iran) enlighten seismogenesis in Mariana-type subduction margins

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DOI	10.1016/j.epsl.2021.117135
	Blueschist-facies paleo-earthquakes in a serpentinite channel (Zagros suture, Iran) enlighten seismogenesis in Mariana-type subduction margins
	Muñoz-Montecinos J.; Angiboust S.; Garcia-Casco A.
发表日期	2021
ISSN	0012821X
卷号	573
英文摘要	The architecture and pressure-temperature conditions reached by a Cretaceous block-in-matrix serpentinite mélange exposed in the Zagros suture resemble those imaged in the active Mariana subduction zone. There, large magnitude-earthquakes (M>w9) have never been recorded but smaller events – of poorly-constrained physical origin – in the range M∼w3-6 are widespread. Field and petro-structural constraints led to a first report of blueschist-facies seismic fault-related rocks in the Zagros serpentinite melange, including breccias, foliated cataclasites and ultracataclasites; all observed within a foliated mafic metatuffaceous block embedded in serpentinite schists. Fine-scale petrological characterization of ultrafine-grained, fluidized cataclastic material reveals the presence of newly-formed glaucophane, lawsonite, phengite, albite and pumpellyite, an assemblage inferred (based on thermodynamic modelling) to have crystallized in the lower lawsonite-blueschist facies at ∼0.6-1.0 GPa and 230-300 °C. Extensional veins containing similar mineral assemblages are observed crosscutting the aforementioned rocks but are also identified as comminuted fragments in all fault-related lithologies. Crosscutting relationships among the multiple generations of fluidized ultracataclasites and brecciated blueschists suggest that episodic faulting and hydrofracturing were contemporaneous processes at ∼20-35 km depth, i.e., at similar conditions as reported for metabasalts expelled by Mariana serpentinite mud volcanoes. Mechanical modelling confirms that the studied fault-related features can only have formed under nearly lithostatic pore fluid pressure conditions, maintaining the system in a critically unstable regime that promoted recurrent seismic faulting, as monitored in the Mariana seismogenic zone. These fluids are likely associated with externally and deeply-generated fluid pulses that may have reached the seismogenic window, imprinting a Ta-Th-Nb-HREEs-enriched trace element signature. This new faulted blueschist occurrence highlights the physical nature and the mechanical processes operating within fluid-saturated fault zones in the serpentinized subduction channel. © 2021 The Author(s)
关键词	blueschists earthquakes Mariana-type margins paleo-earthquakes ultracataclasites Zagros suture
英文关键词	Earthquakes; Faulting; Feldspar; Fluidization; Gasoline; Magnesia; Petrology; Trace elements; Blueschists; Mariana-type margin; matrix; Paleo-earthquake; Pressure-temperature conditions; Seismogenesis; Serpentinite; Subduction zones; Ultracataclasite; Zagros suture; Magnesite
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203234
作者单位	Université de Paris, Institut de physique du globe de Paris, CNRS, Paris, F-75005, France; Department of Mineralogy and Petrology, Faculty of Sciences, University of Granada, Campus Fuentenueva s/n, Granada, 18002, Spain; Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Armilla, Granada, 18100, Spain
推荐引用方式 GB/T 7714	Muñoz-Montecinos J.,Angiboust S.,Garcia-Casco A.. Blueschist-facies paleo-earthquakes in a serpentinite channel (Zagros suture, Iran) enlighten seismogenesis in Mariana-type subduction margins[J],2021,573.
APA	Muñoz-Montecinos J.,Angiboust S.,&Garcia-Casco A..(2021).Blueschist-facies paleo-earthquakes in a serpentinite channel (Zagros suture, Iran) enlighten seismogenesis in Mariana-type subduction margins.Earth and Planetary Science Letters,573.
MLA	Muñoz-Montecinos J.,et al."Blueschist-facies paleo-earthquakes in a serpentinite channel (Zagros suture, Iran) enlighten seismogenesis in Mariana-type subduction margins".Earth and Planetary Science Letters 573(2021).