DOI: 10.1016/j.epsl.2020.116707
论文题名: Nitrogen and noble gases reveal a complex history of metasomatism in the Siberian lithospheric mantle
作者: Barry P.H. ; Broadley M.W.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 556 语种: 英语
中文关键词: argon
; metasomatism
; neon
; nitrogen
; plume
; SCLM
英文关键词: Argon
; Basalt
; Isotopes
; Mineralogy
; Minerals
; Nitrogen
; Recycling
; Structural geology
; Thermal plumes
; Transport properties
; Lithospheric mantle
; Mantle reservoirs
; Mid ocean ridge basalts
; Nitrogen isotopes
; Plume-lithosphere interactions
; Sub-continental lithospheric mantles
; Subducted crustal component
; Volatile elements
; Radiogenic gases
; complexity
; emplacement
; flood basalt
; lithospheric structure
; mantle plume
; mantle structure
; metasomatism
; mid-ocean ridge basalt
; nitrogen
; noble gas
; peridotite
; Permian
; petrogenesis
; xenolith
; Siberia
英文摘要: The Siberian flood basalts (SFB) erupted at the end of the Permian period (∼250 Ma) in response to a deep-rooted mantle plume beneath the Siberian Sub-Continental Lithospheric Mantle (SCLM). Plume-lithosphere interaction can lead to significant changes in the structure and chemistry of the SCLM and trigger the release of metasomatic material that was previously stored within the stable craton. Here, we investigate the nature of the Siberian-SCLM (S-SCLM) by measuring nitrogen abundances and isotopes (δ15N) in 11 samples of two petrologically-distinct suites of peridotitic xenoliths recovered from kimberlites which bracket the eruption of the SFB: the 360 Myr old Udachnaya and 160 Myr old Obnazhennaya pipes. Nitrogen isotope (δ15N) values range from -5.85 ± 1.29‰ to +3.94 ± 0.63‰, which encompasses the entire range between depleted Mid-Ocean Ridge Basalt (MORB) mantle (DMM; -5 ± 2‰) and plume-derived (+3 ± 2‰) endmembers. In addition, we present neon (n=7) and argon (n=8) abundance and isotope results for the same two suites of samples. The 20Ne/22Ne and 21Ne/22Ne range from atmospheric-like values of 9.88 up to 11.35 and from 0.0303 to 0.0385, respectively, suggesting an admixture of DMM and plume-derived components. Argon isotopes (40Ar/36Ar) range from 336.7 to 1122 and correlate positively with 40Ar contents. We show that volatile systematics of Siberian xenoliths: (1) exhibit evidence of ancient metasomatic and/or recycled signatures, and (2) show evidence of subsequent plume-like re-fertilization, which we attribute to the emplacement of the SFB. Metasomatic fluids are highly enriched in radiogenic gases and have elevated Br/Cl and I/Cl values, consistent with an ancient subducted crustal component. The metasomatic component is marked by light N isotope signatures, suggesting it may be derived from an anoxic Archean subducted source. Taken together, these N2-Ne-Ar isotope results suggest that mantle plume impingement has profoundly modified the S-SCLM, and that N, Ne and Ar isotopes are sensitive tracers of metasomatism in the S-SCLM. Metasomatic fluids that permeate the S-SCLM act to archive a “subduction-fingerprint” that can be used to probe relative volatile-element recycling efficiencies and thus provide insight into volatile transport between the surface and mantle reservoirs over Earth history. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165405
Appears in Collections: 气候变化与战略
There are no files associated with this item.
作者单位: Woods Hole Oceanographic Institution, MC&G Dept., Woods Hole, MA 02543, United States; Centre de Recherches Pétrographiques et Géochimiques, Université de Lorraine, Nancy, France
Recommended Citation:
Barry P.H.,Broadley M.W.. Nitrogen and noble gases reveal a complex history of metasomatism in the Siberian lithospheric mantle[J]. Earth and Planetary Science Letters,2021-01-01,556