Isotopic and geochemical studies of nodules in kimberlite have implications for the lower continental crust

M. T. McCulloch; R. J. Arculus; B. W. Chappell; J. Ferguson

doi:10.1038/300166a0

Isotopic and geochemical studies of nodules in kimberlite have implications for the lower continental crust

M. T. McCulloch^*, R. J. Arculus, B. W. Chappell, J. Ferguson

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

37 Citations (Scopus)

Abstract

Lower crustal xenoliths from the Calcutteroo kimberlitic pipes in South AUS show a surprisingly diverse range in Nd and Sr isotopic compositions and rare earth element (REE) abundances. Mafic granulite and garnet-clinopyroxenite xenoliths have measured ε_Nd(0) values between +6.1 and -7.9, both light (L)REE enrichments and depletions, low Rb/Sr ratios (0.005-0.040) and relatively high ⁸⁷Sr/⁸⁶Sr ratios of from 0.70675 to 0.70919. A felsic xenolith has compositions more typical of upper crustal rocks with ε_Nd(0) = -21.4, LREE enrichments, Rb/Sr = 1.47 and ⁸⁷Sr/⁸⁶Sr = 0.85987. An approximate correlation also exists between Sm/Nd versus ¹⁴³Nd/¹⁴⁴Nd and Rb/Sr versus ⁸⁷Sr/⁸⁶Sr indicating major intracrustal differentiation in the lower crust at ∼2,400 Myr. This produced extremely low Rb/Sr ratios, and both relative LREE enrichments (low Sm/Nd) and depletions (high Sm/Nd). If these results are typical, then they indicate that the lower crust has higher ⁸⁷Sr/⁸⁶Sr and more positive ε_Nd(0) values than previous estimates^1-5. This may require revision of total crustal compositions and crust-mantle evolutionary models^1-5.

Original language	English
Pages (from-to)	166-169
Number of pages	4
Journal	Nature
Volume	300
Issue number	5888
DOIs	https://doi.org/10.1038/300166a0
Publication status	Published - 1982

Access to Document

10.1038/300166a0

Cite this

@article{b0ab5e5808d64f62a02995fbbd2a9739,

title = "Isotopic and geochemical studies of nodules in kimberlite have implications for the lower continental crust",

abstract = "Lower crustal xenoliths from the Calcutteroo kimberlitic pipes in South AUS show a surprisingly diverse range in Nd and Sr isotopic compositions and rare earth element (REE) abundances. Mafic granulite and garnet-clinopyroxenite xenoliths have measured εNd(0) values between +6.1 and -7.9, both light (L)REE enrichments and depletions, low Rb/Sr ratios (0.005-0.040) and relatively high 87Sr/86Sr ratios of from 0.70675 to 0.70919. A felsic xenolith has compositions more typical of upper crustal rocks with εNd(0) = -21.4, LREE enrichments, Rb/Sr = 1.47 and 87Sr/86Sr = 0.85987. An approximate correlation also exists between Sm/Nd versus 143Nd/144Nd and Rb/Sr versus 87Sr/86Sr indicating major intracrustal differentiation in the lower crust at ∼2,400 Myr. This produced extremely low Rb/Sr ratios, and both relative LREE enrichments (low Sm/Nd) and depletions (high Sm/Nd). If these results are typical, then they indicate that the lower crust has higher 87Sr/86Sr and more positive εNd(0) values than previous estimates1-5. This may require revision of total crustal compositions and crust-mantle evolutionary models1-5.",

author = "McCulloch, {M. T.} and Arculus, {R. J.} and Chappell, {B. W.} and J. Ferguson",

year = "1982",

doi = "10.1038/300166a0",

language = "English",

volume = "300",

pages = "166--169",

journal = "Nature",

issn = "0028-0836",

publisher = "Nature Publishing Groups",

number = "5888",

}

TY - JOUR

T1 - Isotopic and geochemical studies of nodules in kimberlite have implications for the lower continental crust

AU - McCulloch, M. T.

AU - Arculus, R. J.

AU - Chappell, B. W.

AU - Ferguson, J.

PY - 1982

Y1 - 1982

N2 - Lower crustal xenoliths from the Calcutteroo kimberlitic pipes in South AUS show a surprisingly diverse range in Nd and Sr isotopic compositions and rare earth element (REE) abundances. Mafic granulite and garnet-clinopyroxenite xenoliths have measured εNd(0) values between +6.1 and -7.9, both light (L)REE enrichments and depletions, low Rb/Sr ratios (0.005-0.040) and relatively high 87Sr/86Sr ratios of from 0.70675 to 0.70919. A felsic xenolith has compositions more typical of upper crustal rocks with εNd(0) = -21.4, LREE enrichments, Rb/Sr = 1.47 and 87Sr/86Sr = 0.85987. An approximate correlation also exists between Sm/Nd versus 143Nd/144Nd and Rb/Sr versus 87Sr/86Sr indicating major intracrustal differentiation in the lower crust at ∼2,400 Myr. This produced extremely low Rb/Sr ratios, and both relative LREE enrichments (low Sm/Nd) and depletions (high Sm/Nd). If these results are typical, then they indicate that the lower crust has higher 87Sr/86Sr and more positive εNd(0) values than previous estimates1-5. This may require revision of total crustal compositions and crust-mantle evolutionary models1-5.

AB - Lower crustal xenoliths from the Calcutteroo kimberlitic pipes in South AUS show a surprisingly diverse range in Nd and Sr isotopic compositions and rare earth element (REE) abundances. Mafic granulite and garnet-clinopyroxenite xenoliths have measured εNd(0) values between +6.1 and -7.9, both light (L)REE enrichments and depletions, low Rb/Sr ratios (0.005-0.040) and relatively high 87Sr/86Sr ratios of from 0.70675 to 0.70919. A felsic xenolith has compositions more typical of upper crustal rocks with εNd(0) = -21.4, LREE enrichments, Rb/Sr = 1.47 and 87Sr/86Sr = 0.85987. An approximate correlation also exists between Sm/Nd versus 143Nd/144Nd and Rb/Sr versus 87Sr/86Sr indicating major intracrustal differentiation in the lower crust at ∼2,400 Myr. This produced extremely low Rb/Sr ratios, and both relative LREE enrichments (low Sm/Nd) and depletions (high Sm/Nd). If these results are typical, then they indicate that the lower crust has higher 87Sr/86Sr and more positive εNd(0) values than previous estimates1-5. This may require revision of total crustal compositions and crust-mantle evolutionary models1-5.

UR - http://www.scopus.com/inward/record.url?scp=0019998579&partnerID=8YFLogxK

U2 - 10.1038/300166a0

DO - 10.1038/300166a0

M3 - Article

AN - SCOPUS:0019998579

SN - 0028-0836

VL - 300

SP - 166

EP - 169

JO - Nature

JF - Nature

IS - 5888

ER -

Isotopic and geochemical studies of nodules in kimberlite have implications for the lower continental crust

Abstract

Access to Document

Other files and links

Fingerprint

Cite this