Mapping a hidden terrane boundary in the mantle lithosphere with lamprophyres.

ABSTRACT: Lamprophyres represent hydrous alkaline mantle melts that are a unique source of information about the composition of continental lithosphere. Throughout southwest Britain, post-Variscan lamprophyres are (ultra)potassic with strong incompatible element enrichments. Here we show that they form two distinct groups in terms of their Sr and Nd isotopic compositions, occurring on either side of a postulated, hitherto unrecognized terrane boundary. Lamprophyres emplaced north of the boundary fall on the mantle array with ε_Nd -1 to +1.6. Those south of the boundary are enriched in radiogenic Sr, have initial ε_Nd values of -0.3 to -3.5, and are isotopically indistinguishable from similar-aged lamprophyres in Armorican massifs in Europe. We conclude that an Armorican terrane w

SUBMITTER: Dijkstra AH 

PROVIDER: S-EPMC6138702 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature