气候变化领域集成服务门户(CCPortal): A Laurentian margin subduction perspective: Geodynamic constraints from phase equilibria modeling of barroisite greenstones, northern USA Appalachians

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DOI	10.1130/B35456.1
	A Laurentian margin subduction perspective: Geodynamic constraints from phase equilibria modeling of barroisite greenstones, northern USA Appalachians
	Honsberger I.W.; Laird J.; Johnson J.E.
发表日期	2020
ISSN	167606
起始页码	2587
结束页码	2605
卷号	132 期号:2021-11-12
英文摘要	Phase equilibria modeling of sodic-calcic amphibole-epidote assemblages in greenstones in the northern Appalachians, USA, is compatible with relatively shallow subduction of the early Paleozoic Laurentian margin along the Laurentia-Gondwana suture zone during closure of a portion of the Iapetus Ocean basin. Pseudosection and isopleth calculations demonstrate that peak metamorphic conditions ranged between 0.65 GPa, 480 °C and 0.85 GPa, 495 °C down-dip along the subducted Laurentian continental margin between ∼20 km and ∼30 km depth. Quantitative petrological data are explained in the context of an Early Ordovician geodynamic model involving shallow subduction of relatively young, warm, and buoyant Laurentian margin continental-oceanic lithosphere and Iapetus Ocean crust beneath a relatively warm and wet peri-Gondwanan continental arc. A relatively warm subduction zone setting may have contributed to the formation of a thin, ductile metasedimentary rock-rich channel between the down-going Laurentian slab and the overriding continental arc. This accretionary channel accommodated metamorphism and tectonization of continental margin sediments and mafic volcanic rocks (greenstones) of the Laurentian margin and provided a pathway for exhumation of serpentinite slivers and rare eclogite blocks. Restricted asthenospheric flow in the forearc mantle wedge provides one explanation for the lack of ophiolites and absence of a well-preserved ultra-high-pressure terrane in central and northern Vermont. Exhumation of the subducted portion of the Laurentian margin may have been temperature triggered due to increased asthenospheric flow following a slab tear at relatively shallow depths. © 2020 Geological Society of America. All Rights Reserved.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184836
作者单位	Geological Survey of Canada, 601 Booth St., Ottawa, ON K1A 0E8, Canada; Department of Earth Sciences, University of New Hampshire, 56 College Rd., Durham, NH 03824, United States
推荐引用方式 GB/T 7714	Honsberger I.W.,Laird J.,Johnson J.E.. A Laurentian margin subduction perspective: Geodynamic constraints from phase equilibria modeling of barroisite greenstones, northern USA Appalachians[J],2020,132(2021-11-12).
APA	Honsberger I.W.,Laird J.,&Johnson J.E..(2020).A Laurentian margin subduction perspective: Geodynamic constraints from phase equilibria modeling of barroisite greenstones, northern USA Appalachians.Bulletin of the Geological Society of America,132(2021-11-12).
MLA	Honsberger I.W.,et al."A Laurentian margin subduction perspective: Geodynamic constraints from phase equilibria modeling of barroisite greenstones, northern USA Appalachians".Bulletin of the Geological Society of America 132.2021-11-12(2020).