Publication detail

Magnesium and zinc isotopic evidence for the involvement of recycled carbonates in the petrogenesis of Gaussberg lamproites, Antarctica

LIU, J.-Q. CHEN, L.-H. WANG, X.-J. ZHANG, X.-Y. ZENG, G. ERDMANN, S. MURPHY, D.T. COLLERSON, K.D. KOMIYA, T. KRMÍČEK, L.

Original Title

Magnesium and zinc isotopic evidence for the involvement of recycled carbonates in the petrogenesis of Gaussberg lamproites, Antarctica

Type

journal article in Web of Science

Language

English

Original Abstract

Lamproites are rare mantle-derived peralkaline ultrapotassic rocks, and they are commonly geographically associated with the ultramafic lamprophyres and kimberlites. Their unique geochemistry and mineralogy make determining their mantle source and origin important because of the significance for inferring specific geo-dynamic processes. In this study, we further examine lamproite petrogenesis using new Mg and Zn isotopic data for the typical Gaussberg lamproites, Antarctica, the source of which were thought to be contributed by recycled crustal materials. Results show that these lamproites have lower delta Mg-26 (-0.44%o to-0.39%o) and higher delta 66Zn (0.36 parts per thousand to 0.39 parts per thousand ) values than terrestrial mantle (delta Mg-26 =-0.25 +/- 0.04%o, delta Zn-66 = 0.18 +/- 0.05 parts per thousand ). The post -magmatic alteration and crustal contamination as well as fractional crystallization and partial melting cannot account for these anomalous Mg and Zn isotopic values. By contrast, the involvement of sedimentary carbonates which are characterized by light delta 26Mg (average approximately-2.0%o) and heavy delta 66Zn (average -+0.91%o) values in their mantle source can explain these Mg and Zn isotopic anomalies. Quantitative modelling suggests that addition of 10-15% subducted dolomite into the source of Gaussberg lamproites can well reproduce their Mg and Zn isotopic values. The source component with light Mg and heavy Zn isotopic compositions can either be sub-continental lithospheric mantle metasomatized by carbonate melts or residue of subducted carbonate -bearing sediments after deep melting in the mantle transition zone. A lithospheric mantle contribution is indeed required to explain their strongly enriched radiogenic isotopic compositions. However, in terms of car-bonate component, their positive Zr-Hf anomalies (Hf/Hf* = 1.28-2.19), and extremely high K/U (-40, 000) and Ba/Th (-400) ratios lead us to favor the latter deep recycling model in which the recycled carbonate-bearing sediments subducted as K-hollandite and majorite underwent partial melting within the mantle transition zone.

Keywords

Lamproites; Recycled carbonates; Mantle transition zone; Magnesium isotopes; Zinc isotopes

Authors

LIU, J.-Q.; CHEN, L.-H.; WANG, X.-J.; ZHANG, X.-Y.; ZENG, G.; ERDMANN, S.; MURPHY, D.T.; COLLERSON, K.D.; KOMIYA, T.; KRMÍČEK, L.

Released

20. 10. 2022

Publisher

ELSEVIER

Location

AMSTERDAM

ISBN

0009-2541

Periodical

CHEMICAL GEOLOGY

Year of study

609

Number

10

State

Kingdom of the Netherlands

Pages count

12

URL

https://doi.org/10.1016/j.chemgeo.2022.121067

BibTex

@article{BUT181659,
  author="Jian-Qiang {Liu} and Li-Hui {Chen} and Xiao-Jun {Wang} and Xiao-Yu {Zhang} and Gang {Zeng} and Saskia {Erdmann} and David T. {Murphy} and Kenneth D. {Collerson} and Tsuyoshi {Komiya} and Lukáš {Krmíček}",
  title="Magnesium and zinc isotopic evidence for the involvement of recycled carbonates in the petrogenesis of Gaussberg lamproites, Antarctica",
  journal="CHEMICAL GEOLOGY",
  year="2022",
  volume="609",
  number="10",
  pages="12",
  doi="10.1016/j.chemgeo.2022.121067",
  issn="0009-2541",
  url="https://doi.org/10.1016/j.chemgeo.2022.121067"
}