Single zircon age for the felsic rubbervale formation, Murchison Greenstone Belt, South Africa

Abstract:

Age data for the various greenstone belts of the northern Kaapvaal Craton are generally scarce and imprecise. Single zircons were dated, using the vapour digestion and evaporation techniques, from a felsic metavolcanic rock of the Rubbervale Formation which constitutes an almost 4 km-thick unit within the Murchison Greenstone Belt. Both methods yielded almost identical 207Pb/206Pb ages: 2965.2 ± 1.4 Ma and 2967.5 ± 1.3 Ma, respectively. The combined mean age of 2966.5 ± 1.6 Ma also provides a maximum age for the associated Rooiwater Complex, which is locally intrusive into the Rubbervale Formation. Due to a lack of isotopic data on the mafic portion of the Murchison Belt, its regional setting is speculative. Suggestions are that the belt and the adjacent gneissic terrains represent exotic crustal blocks, or that the Rooiwater Complex together with the Rubbervale Formation formed in an island arc setting.

Año de publicación:

1996

Keywords:

Fuente:

scopus