A combined Re-Os and Pt-Os isotope and HSE abundance study of Ru-Os-Ir alloys from the Kunar and Unga placer deposits, the Taimyr Peninsula, Polar Siberia

Kreshimir N. Malitch; Igor S. Puchtel; Elena A. Belousova; Inna Yu Badanina

doi:10.3390/min12111463

A combined Re-Os and Pt-Os isotope and HSE abundance study of Ru-Os-Ir alloys from the Kunar and Unga placer deposits, the Taimyr Peninsula, Polar Siberia

Kreshimir N. Malitch^*, Igor S. Puchtel, Elena A. Belousova, Inna Yu Badanina

^*Corresponding author for this work

ARC Centre of Excellence for Core to Crust Fluid Systems (incorporation ARC National Key Centre for Geochemical evolution and Metallogeny of Continents (GEMOC))

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

3 Citations (Scopus)

75 Downloads (Pure)

Abstract

In order to provide further insights into the origin of Ru-Os-Ir alloys, this study presents new highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundance and ¹⁸⁷Re-¹⁸⁷Os and ¹⁹⁰Pt-¹⁸⁶Os isotope data for detrital grains of native Ru-Os-Ir alloys in placer deposits of the Kunar and Unga Rivers, which display a close spatial association with the Kunar dunite–harzburgite complex in the northern part of the Taimyr Peninsula in the Polar Siberia. The study utilized electron microprobe analysis, negative thermal ionization mass-spectrometry (N-TIMS) and laser ablation multiple-collector inductively coupled plasma mass-spectrometry (LA MC-ICP-MS). The primary nature of the Ru-Os-Ir alloys is supported by the occurrence of euhedral inclusions of high-Mg olivine (Fo_92–93) that fall within the compositional range of mantle olivine. The LA MC-ICP-MS data show similar average initial ¹⁸⁷Os/¹⁸⁸Os and γ¹⁸⁷Os(740 Ma) values for PGM assemblages from the Kunar and Unga deposits of 0.1218 ± 0.0010, −0.18 ± 0.85, and 0.1222 ± 0.0025, +0.10 ± 2.1, respectively. These values are identical, within their respective uncertainties, to the initial ¹⁸⁷Os/¹⁸⁸Os value of the Ru-Os-Ir alloy grain measured by N-TIMS (0.1218463 ± 0.0000015, γ¹⁸⁷Os(740 Ma) = −0.1500 ± 0.0012). The combined ¹⁸⁷Re-¹⁸⁷Os isotopic data for all studied grains (γ¹⁸⁷Os(740 Ma) = −0.02 ± 1.6) indicate evolution of the Kunar and Unga mantle sources with a long-term chondritic ¹⁸⁷Re/¹⁸⁸Os ratio of 0.401 ± 0.030. In contrast to the ¹⁸⁷Os/¹⁸⁸Os data, the initial ¹⁸⁶Os/¹⁸⁸Os value of 0.1198409 ± 0.0000012 (µ¹⁸⁶Os(740 Ma) = +34 ± 10) obtained for the same Ru-Os-Ir alloy grain by N-TIMS is suprachondritic and implies evolution of the Kunar and Unga mantle source(s) with a long-term suprachondritic ¹⁹⁰Pt/¹⁸⁸Os ratio of 0.00247 ± 0.00021. This value is ~40% higher than the average chondritic ¹⁹⁰Pt/¹⁸⁸Os ratio of 0.00180 and indicates long-term enrichment of the Kunar source in Pt over Os. Establishing the source of this enrichment requires further investigation.

Original language	English
Article number	1463
Pages (from-to)	1-19
Number of pages	19
Journal	Minerals
Volume	12
Issue number	11
DOIs	https://doi.org/10.3390/min12111463
Publication status	Published - Nov 2022

Bibliographical note

Copyright the Author(s) 2022. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

highly siderophile elements
mantle
ophiolite
Polar Siberia
Re-Os and Pt-Os isotopic systems
Ru-Os-Ir alloys
the Kunar and Unga placer deposits
the Taimyr Peninsula

Access to Document

10.3390/min12111463Licence: CC BY

Publisher version (open access)Final published version, 2.67 MBLicence: CC BY

Cite this

@article{a3644ba7d4a747cb9cfd40c26d45909c,

title = "A combined Re-Os and Pt-Os isotope and HSE abundance study of Ru-Os-Ir alloys from the Kunar and Unga placer deposits, the Taimyr Peninsula, Polar Siberia",

abstract = "In order to provide further insights into the origin of Ru-Os-Ir alloys, this study presents new highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundance and 187Re-187Os and 190Pt-186Os isotope data for detrital grains of native Ru-Os-Ir alloys in placer deposits of the Kunar and Unga Rivers, which display a close spatial association with the Kunar dunite–harzburgite complex in the northern part of the Taimyr Peninsula in the Polar Siberia. The study utilized electron microprobe analysis, negative thermal ionization mass-spectrometry (N-TIMS) and laser ablation multiple-collector inductively coupled plasma mass-spectrometry (LA MC-ICP-MS). The primary nature of the Ru-Os-Ir alloys is supported by the occurrence of euhedral inclusions of high-Mg olivine (Fo92–93) that fall within the compositional range of mantle olivine. The LA MC-ICP-MS data show similar average initial 187Os/188Os and γ187Os(740 Ma) values for PGM assemblages from the Kunar and Unga deposits of 0.1218 ± 0.0010, −0.18 ± 0.85, and 0.1222 ± 0.0025, +0.10 ± 2.1, respectively. These values are identical, within their respective uncertainties, to the initial 187Os/188Os value of the Ru-Os-Ir alloy grain measured by N-TIMS (0.1218463 ± 0.0000015, γ187Os(740 Ma) = −0.1500 ± 0.0012). The combined 187Re-187Os isotopic data for all studied grains (γ187Os(740 Ma) = −0.02 ± 1.6) indicate evolution of the Kunar and Unga mantle sources with a long-term chondritic 187Re/188Os ratio of 0.401 ± 0.030. In contrast to the 187Os/188Os data, the initial 186Os/188Os value of 0.1198409 ± 0.0000012 (µ186Os(740 Ma) = +34 ± 10) obtained for the same Ru-Os-Ir alloy grain by N-TIMS is suprachondritic and implies evolution of the Kunar and Unga mantle source(s) with a long-term suprachondritic 190Pt/188Os ratio of 0.00247 ± 0.00021. This value is ~40% higher than the average chondritic 190Pt/188Os ratio of 0.00180 and indicates long-term enrichment of the Kunar source in Pt over Os. Establishing the source of this enrichment requires further investigation.",

keywords = "highly siderophile elements, mantle, ophiolite, Polar Siberia, Re-Os and Pt-Os isotopic systems, Ru-Os-Ir alloys, the Kunar and Unga placer deposits, the Taimyr Peninsula",

author = "Malitch, {Kreshimir N.} and Puchtel, {Igor S.} and Belousova, {Elena A.} and Badanina, {Inna Yu}",

note = "Copyright the Author(s) 2022. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",

year = "2022",

month = nov,

doi = "10.3390/min12111463",

language = "English",

volume = "12",

pages = "1--19",

journal = "Minerals",

issn = "2075-163X",

publisher = "MDPI",

number = "11",

}

TY - JOUR

T1 - A combined Re-Os and Pt-Os isotope and HSE abundance study of Ru-Os-Ir alloys from the Kunar and Unga placer deposits, the Taimyr Peninsula, Polar Siberia

AU - Malitch, Kreshimir N.

AU - Puchtel, Igor S.

AU - Belousova, Elena A.

AU - Badanina, Inna Yu

N1 - Copyright the Author(s) 2022. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2022/11

Y1 - 2022/11

N2 - In order to provide further insights into the origin of Ru-Os-Ir alloys, this study presents new highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundance and 187Re-187Os and 190Pt-186Os isotope data for detrital grains of native Ru-Os-Ir alloys in placer deposits of the Kunar and Unga Rivers, which display a close spatial association with the Kunar dunite–harzburgite complex in the northern part of the Taimyr Peninsula in the Polar Siberia. The study utilized electron microprobe analysis, negative thermal ionization mass-spectrometry (N-TIMS) and laser ablation multiple-collector inductively coupled plasma mass-spectrometry (LA MC-ICP-MS). The primary nature of the Ru-Os-Ir alloys is supported by the occurrence of euhedral inclusions of high-Mg olivine (Fo92–93) that fall within the compositional range of mantle olivine. The LA MC-ICP-MS data show similar average initial 187Os/188Os and γ187Os(740 Ma) values for PGM assemblages from the Kunar and Unga deposits of 0.1218 ± 0.0010, −0.18 ± 0.85, and 0.1222 ± 0.0025, +0.10 ± 2.1, respectively. These values are identical, within their respective uncertainties, to the initial 187Os/188Os value of the Ru-Os-Ir alloy grain measured by N-TIMS (0.1218463 ± 0.0000015, γ187Os(740 Ma) = −0.1500 ± 0.0012). The combined 187Re-187Os isotopic data for all studied grains (γ187Os(740 Ma) = −0.02 ± 1.6) indicate evolution of the Kunar and Unga mantle sources with a long-term chondritic 187Re/188Os ratio of 0.401 ± 0.030. In contrast to the 187Os/188Os data, the initial 186Os/188Os value of 0.1198409 ± 0.0000012 (µ186Os(740 Ma) = +34 ± 10) obtained for the same Ru-Os-Ir alloy grain by N-TIMS is suprachondritic and implies evolution of the Kunar and Unga mantle source(s) with a long-term suprachondritic 190Pt/188Os ratio of 0.00247 ± 0.00021. This value is ~40% higher than the average chondritic 190Pt/188Os ratio of 0.00180 and indicates long-term enrichment of the Kunar source in Pt over Os. Establishing the source of this enrichment requires further investigation.

AB - In order to provide further insights into the origin of Ru-Os-Ir alloys, this study presents new highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundance and 187Re-187Os and 190Pt-186Os isotope data for detrital grains of native Ru-Os-Ir alloys in placer deposits of the Kunar and Unga Rivers, which display a close spatial association with the Kunar dunite–harzburgite complex in the northern part of the Taimyr Peninsula in the Polar Siberia. The study utilized electron microprobe analysis, negative thermal ionization mass-spectrometry (N-TIMS) and laser ablation multiple-collector inductively coupled plasma mass-spectrometry (LA MC-ICP-MS). The primary nature of the Ru-Os-Ir alloys is supported by the occurrence of euhedral inclusions of high-Mg olivine (Fo92–93) that fall within the compositional range of mantle olivine. The LA MC-ICP-MS data show similar average initial 187Os/188Os and γ187Os(740 Ma) values for PGM assemblages from the Kunar and Unga deposits of 0.1218 ± 0.0010, −0.18 ± 0.85, and 0.1222 ± 0.0025, +0.10 ± 2.1, respectively. These values are identical, within their respective uncertainties, to the initial 187Os/188Os value of the Ru-Os-Ir alloy grain measured by N-TIMS (0.1218463 ± 0.0000015, γ187Os(740 Ma) = −0.1500 ± 0.0012). The combined 187Re-187Os isotopic data for all studied grains (γ187Os(740 Ma) = −0.02 ± 1.6) indicate evolution of the Kunar and Unga mantle sources with a long-term chondritic 187Re/188Os ratio of 0.401 ± 0.030. In contrast to the 187Os/188Os data, the initial 186Os/188Os value of 0.1198409 ± 0.0000012 (µ186Os(740 Ma) = +34 ± 10) obtained for the same Ru-Os-Ir alloy grain by N-TIMS is suprachondritic and implies evolution of the Kunar and Unga mantle source(s) with a long-term suprachondritic 190Pt/188Os ratio of 0.00247 ± 0.00021. This value is ~40% higher than the average chondritic 190Pt/188Os ratio of 0.00180 and indicates long-term enrichment of the Kunar source in Pt over Os. Establishing the source of this enrichment requires further investigation.

KW - highly siderophile elements

KW - mantle

KW - ophiolite

KW - Polar Siberia

KW - Re-Os and Pt-Os isotopic systems

KW - Ru-Os-Ir alloys

KW - the Kunar and Unga placer deposits

KW - the Taimyr Peninsula

UR - http://www.scopus.com/inward/record.url?scp=85149580060&partnerID=8YFLogxK

U2 - 10.3390/min12111463

DO - 10.3390/min12111463

M3 - Article

AN - SCOPUS:85149580060

SN - 2075-163X

VL - 12

SP - 1

EP - 19

JO - Minerals

JF - Minerals

IS - 11

M1 - 1463

ER -

A combined Re-Os and Pt-Os isotope and HSE abundance study of Ru-Os-Ir alloys from the Kunar and Unga placer deposits, the Taimyr Peninsula, Polar Siberia

Abstract

Bibliographical note

Keywords

Access to Document

Other files and links

Fingerprint

Cite this