Neodymium and Strontium Isotopic Measurements on Single Subcalcic Garnet Grains from Yakutian Kimberlites

D. E. Jacob; E. Jagoutz; N. V. Sobolev

Neodymium and Strontium Isotopic Measurements on Single Subcalcic Garnet Grains from Yakutian Kimberlites

D. E. Jacob^*, E. Jagoutz, N. V. Sobolev

^*Corresponding author for this work

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

19 Citations (SciVal)

Abstract

Discrete grains of subcalcic garnets from Yakutian kimberlites have been investigated for major elements, Sm, Sr, Nd, Rb concentrations as well as for ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd ratios. ε_Ndi-values range between +1 and -40.6, ⁸⁷Sr/⁸⁶Sr are between 0.70521 and 0.72632, confirming the very heterogeneous character of these minerals. Sm/Nd ratios range from 0.025 to 0.828. Strong positive correlations of ⁸⁷Sr/⁸⁶Sr-ratios with Cr and Mn are consistent with an origin of the subcalcic garnets from Cr-spinels from spinel-harzburgites which were subducted into depths of the diamond stability field and reacted there with a metasomatic agent producing subcalcic garnet and olivine at the expense of Cr-spinel, orthopyroxene and any remaining clinopyroxene. It is proposed that subcalcic garnets are formed episodically through time and that kimber-lites randomly sample populations of these minerals which are not necessarily cogenetic.

Original language	English
Pages (from-to)	357-379
Number of pages	23
Journal	Neues Jahrbuch fur Mineralogie, Abhandlungen
Volume	172
Issue number	2-3
Publication status	Published - 1998
Externally published	Yes

Cite this

@article{d5b333c64a7545f58aa60f43ff322c34,

title = "Neodymium and Strontium Isotopic Measurements on Single Subcalcic Garnet Grains from Yakutian Kimberlites",

abstract = "Discrete grains of subcalcic garnets from Yakutian kimberlites have been investigated for major elements, Sm, Sr, Nd, Rb concentrations as well as for 87Sr/86Sr and 143Nd/144Nd ratios. εNdi-values range between +1 and -40.6, 87Sr/86Sr are between 0.70521 and 0.72632, confirming the very heterogeneous character of these minerals. Sm/Nd ratios range from 0.025 to 0.828. Strong positive correlations of 87Sr/86Sr-ratios with Cr and Mn are consistent with an origin of the subcalcic garnets from Cr-spinels from spinel-harzburgites which were subducted into depths of the diamond stability field and reacted there with a metasomatic agent producing subcalcic garnet and olivine at the expense of Cr-spinel, orthopyroxene and any remaining clinopyroxene. It is proposed that subcalcic garnets are formed episodically through time and that kimber-lites randomly sample populations of these minerals which are not necessarily cogenetic.",

keywords = "Diamond indicator, Nd/Nd, Spinel harzburgites, Sr/Sr, Subcalcic garnets, Trace elements",

author = "Jacob, {D. E.} and E. Jagoutz and Sobolev, {N. V.}",

year = "1998",

language = "English",

volume = "172",

pages = "357--379",

journal = "Neues Jahrbuch fur Mineralogie, Abhandlungen",

issn = "0077-7757",

publisher = "Schweizerbart Science Publishers",

number = "2-3",

}

TY - JOUR

T1 - Neodymium and Strontium Isotopic Measurements on Single Subcalcic Garnet Grains from Yakutian Kimberlites

AU - Jacob, D. E.

AU - Jagoutz, E.

AU - Sobolev, N. V.

PY - 1998

Y1 - 1998

N2 - Discrete grains of subcalcic garnets from Yakutian kimberlites have been investigated for major elements, Sm, Sr, Nd, Rb concentrations as well as for 87Sr/86Sr and 143Nd/144Nd ratios. εNdi-values range between +1 and -40.6, 87Sr/86Sr are between 0.70521 and 0.72632, confirming the very heterogeneous character of these minerals. Sm/Nd ratios range from 0.025 to 0.828. Strong positive correlations of 87Sr/86Sr-ratios with Cr and Mn are consistent with an origin of the subcalcic garnets from Cr-spinels from spinel-harzburgites which were subducted into depths of the diamond stability field and reacted there with a metasomatic agent producing subcalcic garnet and olivine at the expense of Cr-spinel, orthopyroxene and any remaining clinopyroxene. It is proposed that subcalcic garnets are formed episodically through time and that kimber-lites randomly sample populations of these minerals which are not necessarily cogenetic.

AB - Discrete grains of subcalcic garnets from Yakutian kimberlites have been investigated for major elements, Sm, Sr, Nd, Rb concentrations as well as for 87Sr/86Sr and 143Nd/144Nd ratios. εNdi-values range between +1 and -40.6, 87Sr/86Sr are between 0.70521 and 0.72632, confirming the very heterogeneous character of these minerals. Sm/Nd ratios range from 0.025 to 0.828. Strong positive correlations of 87Sr/86Sr-ratios with Cr and Mn are consistent with an origin of the subcalcic garnets from Cr-spinels from spinel-harzburgites which were subducted into depths of the diamond stability field and reacted there with a metasomatic agent producing subcalcic garnet and olivine at the expense of Cr-spinel, orthopyroxene and any remaining clinopyroxene. It is proposed that subcalcic garnets are formed episodically through time and that kimber-lites randomly sample populations of these minerals which are not necessarily cogenetic.

KW - Diamond indicator

KW - Nd/Nd

KW - Spinel harzburgites

KW - Sr/Sr

KW - Subcalcic garnets

KW - Trace elements

UR - http://www.scopus.com/inward/record.url?scp=0032329644&partnerID=8YFLogxK

M3 - Article

SN - 0077-7757

VL - 172

SP - 357

EP - 379

JO - Neues Jahrbuch fur Mineralogie, Abhandlungen

JF - Neues Jahrbuch fur Mineralogie, Abhandlungen

IS - 2-3

ER -

Neodymium and Strontium Isotopic Measurements on Single Subcalcic Garnet Grains from Yakutian Kimberlites

Abstract

Other files and links

Fingerprint

Cite this