What is it about?
The Mesozoic dykes related to the distribution of Karoo plume on the territory of East Antarctica are studied. It is shown that magnesian high-Ti ferrobasalts are found in the area of Ahlmannryggen massif. Their formation is determined by melting of the mantle that contains pyroxenite.
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Why is it important?
The isotope characteristics of the studied dolerites reflect the composition of a pyroxenite source, i.e., the ancient oceanic lithosphere (EMI) that subsided to the mantle depths of 150–170 km in the paleosubduction zone of the continent of Gondwana and was transformed to the pyroxenite melt 180 Ma ago during the interaction with mantle peridotite of the plume.
Perspectives
The unique features of pyroxenite high-Fe magnesian melts discovered in the different parts of Karoo province and QML (high-Ti trap Karoo province is a central part of Karoo and the southern part of QML) are determined also by the fact that they are confined only to the central part of the plume and might conform to the earliest eruptions. The latter is confirmed by a few age estimates of basalts from Ahlmannryggen massif at 200–192 Ma. The evolution of the plume composition leads to the fact that the inclusion of pyroxenites in the mantle wedge decreases with time and that the melts acquire characteristics of the melting lithospheric mantle, which is reflected in the isotopic composition by an increased share of matter of the enriched component of type EMII.
Boris V Belyatsky
Karpinsky Geological Institute (VSEGEI)
Read the Original
This page is a summary of: Geochemical Characteristics of Jurassic Plume Magmatism in Ahlmannryggen Massif (Queen Maud Land, East Antarctica), Doklady Earth Sciences, May 2019, Pleiades Publishing Ltd,
DOI: 10.1134/s1028334x19050076.
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