DOI: 10.1016/j.epsl.2018.03.049
Scopus记录号: 2-s2.0-85045750807
论文题名: Unexpected HIMU-type late-stage volcanism on the Walvis Ridge
作者: Homrighausen S. ; Hoernle K. ; Geldmacher J. ; Wartho J.-A. ; Hauff F. ; Portnyagin M. ; Werner R. ; van den Bogaard P. ; Garbe-Schönberg D.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 492 起始页码: 251
结束页码: 263
语种: 英语
英文关键词: 40Ar/39Ar dating
; high 238U/204Pb (HIMU) mantle end member
; Large Low Shear Velocity Province (LLSVP)
; late-stage volcanism
; trace elements and isotope geochemistry
; Walvis Ridge
Scopus关键词: Buildings
; Exploratory geochemistry
; Isotopes
; Mixing
; Shear flow
; Trace elements
; Volcanoes
; Endmembers
; Isotope geochemistry
; Late stage
; Shear velocities
; Walvis Ridge
; ^40Ar/^39Ar dating
; Submarine geology
; argon-argon dating
; geochemistry
; isotopic composition
; mantle plume
; seamount
; trace element
; uranium series dating
; volcanism
; Atlantic Ocean
; Walvis Ridge
英文摘要: Volcanic activity at many oceanic volcanoes, ridges and plateaus often reawakens after hiatuses of up to several million years. Compared to the earlier magmatic phases, this late-stage (rejuvenated/post-erosional) volcanism is commonly characterized by a distinct geochemical composition. Late-stage volcanism raises two hitherto unanswered questions: Why does volcanism restart after an extended hiatus and what is the origin of this volcanism? Here we present the first 40Ar/39Ar age and comprehensive trace element and Sr–Nd–Pb–Hf isotopic data from seamounts located on and adjacent to the Walvis Ridge in the South Atlantic ocean basin. The Walvis Ridge is the oldest submarine part of the Tristan-Gough hotspot track and is famous as the original type locality for the enriched mantle one (EM I) end member. Consistent with the bathymetric data, the age data indicates that most of these seamounts are 20–40 Myr younger than the underlying or nearby Walvis Ridge basement. The trace element and isotope data reveal a distinct compositional range from the EM I-type basement. The composition of the seamounts extend from the St. Helena HIMU (high time-integrated 238U/204Pb mantle with radiogenic Pb isotope ratios) end member to an enriched (E) Mid-Ocean-Ridge Basalt (MORB) type composition, reflecting a two-component mixing trend on all isotope diagrams. The EMORB end member could have been generated through mixing of Walvis Ridge EM I with normal (N) MORB source mantle, reflecting interaction of Tristan-Gough (EM I-type) plume melts with the upper mantle. The long volcanic quiescence and the HIMU-like geochemical signature of the seamounts are unusual for classical hotspot related late-stage volcanism, indicating that these seamounts are not related to the Tristan-Gough hotspot volcanism. Two volcanic arrays in southwestern Africa (Gibeon-Dicker Willem and Western Cape province) display similar ages to the late-stage Walvis seamounts and also have HIMU-like compositions, suggesting a larger-scale event at ∼77–49 Ma. We propose that the EM I-like mantle plumes rise from the edges of the African Large Low Shear Velocity Province (LLSVP; Tristan-Gough, Discovery and Shona hotspot), whereas the HIMU-dominated intraplate lavas (St. Helena, Gibeon-Dicker Willem and Western Cape province) and the late-stage Walvis seamounts tap material from internal portions of the African LLSVP, suggesting possible lateral and/or vertical chemical zonation of the African LLSVP. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109904
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Wischhofstr. 1-3, Kiel, 24148, Germany; Institut für Geowissenschaften, Christian-Albrechts Universität zu Kiel, Ludewig-Meyn-Str. 10, Kiel, 24118, Germany; V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, Kosygin St. 19, Moscow, 119991, Russian Federation
Recommended Citation:
Homrighausen S.,Hoernle K.,Geldmacher J.,et al. Unexpected HIMU-type late-stage volcanism on the Walvis Ridge[J]. Earth and Planetary Science Letters,2018-01-01,492