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Multistage mantle metasomatism deciphered by Mg−Sr−Nd−Pb isotopes in the Leucite Hills lamproites.
- Source :
-
Contributions to Mineralogy & Petrology . Jun2021, Vol. 176 Issue 6, p1-12. 12p. - Publication Year :
- 2021
-
Abstract
- Cratonic lamproites bear extreme Sr−Nd−Pb isotopic compositions widely known as enriched mantle I (EMI), yet the origin of the EMI reservoir remains controversial. Here, we explore this issue by examining Mg−Sr−Nd−Pb isotopic compositions of lamproites from Leucite Hills, Wyoming, USA. The δ26Mg values vary from the range of the normal mantle to lower values (− 0.43 to − 0.18 ‰), correlating with indices of the degree of carbonate metasomatism, an observation that can be best explained through mantle metasomatism by subducted carbonate-bearing sediments. With increasing extent of carbonate metasomatism, these samples display less extreme EMI Sr−Nd−Pb isotopic signatures, arguing for at least two metasomatic events that occurred in their mantle sources. The early metasomatic event associated with subducted continent-derived siliciclastic sediments led to the formation of the EMI Sr−Nd−Pb isotopic signatures while the recent carbonate metasomatism produced the light Mg isotopic signature but diluted the EMI Sr−Nd−Pb isotopic signatures. Our study indicates that a combination of Mg and Sr−Nd−Pb isotopes could be an effective tool in deciphering multiple-stage metasomatic events in mantle sources and places new constraints on the generation of enriched mantle reservoirs. [ABSTRACT FROM AUTHOR]
- Subjects :
- *METASOMATISM
*ISOTOPIC signatures
*ISOTOPES
*CARBONATES
Subjects
Details
- Language :
- English
- ISSN :
- 00107999
- Volume :
- 176
- Issue :
- 6
- Database :
- Academic Search Index
- Journal :
- Contributions to Mineralogy & Petrology
- Publication Type :
- Academic Journal
- Accession number :
- 151103636
- Full Text :
- https://doi.org/10.1007/s00410-021-01801-9