DOI: 10.1016/j.epsl.2018.03.016
Scopus记录号: 2-s2.0-85044070438
论文题名: Diamond ages from Victor (Superior Craton): Intra-mantle cycling of volatiles (C, N, S) during supercontinent reorganisation
作者: Aulbach S. ; Creaser R.A. ; Stachel T. ; Heaman L.M. ; Chinn I.L. ; Kong J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 490 起始页码: 77
结束页码: 87
语种: 英语
英文关键词: Attawapiskat
; carbon cycle
; continents
; kimberlite magmatism
; lithospheric mantle
; supercontinent breakup
Scopus关键词: Diamond deposits
; Diamonds
; Gallium
; Isotopes
; Lakes
; Mass spectrometry
; Minerals
; Osmium
; Osmium compounds
; Silicate minerals
; Solvents
; Sulfur compounds
; Tectonics
; Volcanic rocks
; Attawapiskat
; Carbon cycles
; continents
; Lithospheric mantle
; Magmatisms
; Supercontinents
; Economic geology
; carbon cycle
; continental breakup
; diamond
; kimberlite
; lithosphere
; magmatism
; mantle structure
; supercontinent
; Attawapiskat
; Canada
; Ontario [Canada]
英文摘要: The central Superior Craton hosts both the diamondiferous 1.1 Ga Kyle Lake and Jurassic Attawapiskat kimberlites. A major thermal event related to the Midcontinent Rift at ca. 1.1 Ga induced an elevated geothermal gradient that largely destroyed an older generation of diamonds, raising the question of when, and how, the diamond inventory beneath Attawapiskat was formed. We determined Re–Os isotope systematics of sulphides included in diamonds from Victor by isotope dilution negative thermal ionisation mass spectrometry in order to obtain insights into the age and nature of the diamond source in the context of regional tectonothermal evolution. Regression of the peridotitic inclusion data (n=14 of 16) yields a 718 ± 49 Ma age, with an initial 187Os/188Os ratio of 0.1177 ± 0.0016, i.e. depleted at the time of formation (γOs −3.7 ± 1.3). Consequently, Re depletion model ages calculated for these samples are systematically overestimated. Given that reported 187Os/188Os in olivine from Attawapiskat xenoliths varies strongly (0.1012–0.1821), the low and nearly identical initial Os of sulphide inclusions combined with their high 187Re/188Os (median 0.34) suggest metasomatic formation from a mixed source. This was likely facilitated by percolation of amounts of melt sufficient to homogenise Os, (re)crystallise sulphide and (co)precipitate diamond; that is, the sulphide inclusions and their diamond host are synchronous if not syngenetic. The ∼720 Ma age corresponds to rifting beyond the northern craton margin during Rodinia break-up. This suggests mobilisation of volatiles (C, N, S) and Os due to attendant mantle stretching and metasomatism by initially oxidising and S-undersaturated melts, which ultimately produced lherzolitic diamonds with high N contents compared to older Kyle Lake diamonds. Thus, some rift-influenced settings are prospective with respect to diamond formation. They are also important sites of hidden, intra-lithospheric volatile redistribution that can be revealed by diamond studies. Later emplacement of the Attawapiskat kimberlites, linking the carbon cycle to the surface, was associated with renewed disturbance during passage of the Great Meteor Hotspot. Lherzolitic diamond formation from oxidising small-volume melts may be the expression of an early and deep stage of the lithospheric conditioning required for the successful eruption of kimberlites, which complements the late and shallow emplacement of volatile-rich metasomes after upward displacement of a redox freezing front. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109949
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: University of Alberta, Earth and Atmospheric Sciences, Edmonton, AB, Canada; Institut für Geowissenschaften, Goethe-Universität, Frankfurt am Main, Germany; De Beers Exploration, Southdale, South Africa; De Beers Canada, Toronto, Canada
Recommended Citation:
Aulbach S.,Creaser R.A.,Stachel T.,et al. Diamond ages from Victor (Superior Craton): Intra-mantle cycling of volatiles (C, N, S) during supercontinent reorganisation[J]. Earth and Planetary Science Letters,2018-01-01,490