气候变化领域集成服务门户(CCPortal): Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum

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DOI	10.1016/j.epsl.2020.116147
	Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum
	Guimarães A.R.; Fitton J.G.; Kirstein L.A.; Barfod D.N.
发表日期	2020
ISSN	0012821X
卷号	536
英文摘要	Intraplate magmatism is enigmatic in origin despite its importance in our understanding of crustal cycling through the deep mantle. A mantle plume origin is justified for some intraplate magmatism, but not in the case of a large number of occurrences. Here we present a novel explanation for intraplate magmatism in situations where evidence for a plume origin is either lacking or equivocal. Specifically, we highlight two voluminous, long-lived intraplate magmatic provinces located on the precisely conjugate continental margins of Cameroon and NE Brazil and which lasted, respectively, from 65 and 52 Ma to the present. New Ar dating and geochemical data show that magmatism in the two provinces was contemporaneous, identical in incompatible-element composition, and started >40 Myr after continental separation, when the two margins were ∼2000 km apart. Lack of age progression in magmatic activity rules out a mantle plume origin. We propose an origin in sub-continental lithospheric mantle that was thickened during Gondwana supercontinent assembly. Thermal re-equilibration of the thickened lithosphere accompanied by percolation of carbonate-rich melt led to the formation of a thick zone of newly created, enriched asthenosphere that is held in place by buoyancy, prevented from dispersing by adjacent lithospheric blocks, and heated by radioactive decay. Following continental breakup at 105 Ma, slow outward drainage of this enriched and heated asthenosphere was channelled into thinner parts of the continental and oceanic lithosphere. Sublithospheric drainage and decompression melting of this enriched mantle provides a viable explanation for these and many other intraplate magmatic occurrences. © 2020 Elsevier B.V.
关键词	Cameroon line geochronology Gondwana intraplate magmatism mantle enrichment Pan-African
英文关键词	Geochronology; Solvents; Cameroon; Continental break-up; Decompression melting; Gondwana; Incompatible element; Magmatisms; Pan-African; Sub-continental lithospheric mantles; Thermal plumes; continental margin; enrichment; geochronology; Gondwana; hot spot; igneous geochemistry; intraplate process; magmatism; mantle plume; Atlantic Ocean; Atlantic Ocean (South); Brazil; Cameroon
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/202623
作者单位	School of GeoSciences, University of Edinburgh, James Hutton Road, Edinburgh, EH9 3FE, United Kingdom; NERC Argon Isotope Facility, Scottish Universities Environmental Research Centre, Rankine Avenue, East Kilbride, G75 0QF, United Kingdom
推荐引用方式 GB/T 7714	Guimarães A.R.,Fitton J.G.,Kirstein L.A.,et al. Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum[J],2020,536.
APA	Guimarães A.R.,Fitton J.G.,Kirstein L.A.,&Barfod D.N..(2020).Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum.Earth and Planetary Science Letters,536.
MLA	Guimarães A.R.,et al."Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum".Earth and Planetary Science Letters 536(2020).