Role of Pyroxenite Mantle in the Formation of the Mesozoic Karoo Plume Melts: Evidence from the Western Queen Maud Land, East Antarctica

Petrological and geochemical study of basalts and dolerites in East Antarctica, the formation of which is explained by the Karoo plume impact on the Queen Maud Land, revealed the presence of high-magnesium magmas, Fe-rich and depleted in incompatible elements, among the geochemically diverse magmas....

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Bibliographic Details
Published in:Geochemistry international 2021-04, Vol.59 (4), p.357-376
Main Authors: Sushchevskaya, N. M., Sobolev, A. V., Leitchenkov, G. L., Batanova, V. G., Belyatsky, B. V., Zhilkina, A. V.
Format: Article
Language:English
Subjects:
Basalt
Composition
Earth
Earth and Environmental Science
Earth Sciences
Erbium
Geochemistry
Iron
Isotopes
Lead isotopes
Magnesium
Mantle
Massifs
Melts
Mesozoic
Neodymium
Neodymium isotopes
Ytterbium
Yttrium
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Summary:Petrological and geochemical study of basalts and dolerites in East Antarctica, the formation of which is explained by the Karoo plume impact on the Queen Maud Land, revealed the presence of high-magnesium magmas, Fe-rich and depleted in incompatible elements, among the geochemically diverse magmas. Such high-Mg ferropicrites are scarce in other plume-related igneous provinces and their genesis is related to melting of a peculiar pyroxenite mantle source. These rocks were found only in the Ahlmannryggen and Vestfjella massifs in Antarctica and in the Letabo province in South Africa, correspond to the central part of the plume and likely the earliest eruptions. The studied dolerites are close to the parental melts. They have a relatively smoothed lithophile element pattern (from Th to Er), the lowered content of most compatible elements (Y, Yb, Lu), as well as the low 206 Pb/ 204 Pb = 17.33–17.37 and moderately radiogenic neodymium composition with 143 Nd/ 144 Nd from 0.51249 to 0.51259, which indicate a relatively old age of the pyroxenite component. All high-Ti basalts related to the Karoo–Maud plume point to the presence of this component in their compositions, but its proportion could significantly vary.
ISSN:0016-7029
1556-1968
DOI:10.1134/S001670292104008X