DOI: 10.1016/j.epsl.2020.116147
论文题名: Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum
作者: Guimarães A.R. ; Fitton J.G. ; Kirstein L.A. ; Barfod D.N.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 536 语种: 英语
中文关键词: 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165001
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
Guimarães A.R.,Fitton J.G.,Kirstein L.A.,et al. Contemporaneous intraplate magmatism on conjugate South Atlantic margins: A hotspot conundrum[J]. Earth and Planetary Science Letters,2020-01-01,536