A palaeomagnetic study of the Umvimeela Dyke, Zimbabwe: evidence for a Mesoproterozoic overprint

摘要: Abstract Palaeomagnetic and magnetic susceptibility results are reported from sixteen new sites (complementing the previous seven) on Umvimeela Dyke, one of two major satellite dykes parallelling Great Dyke Zimbabwe. Four in deformed northernmost section dyke with a further four just to their south. The magnetisation long cratonic is characterised by component P, carried principally magnetite considered primary, mean direction D =219.8°, I =−58.7° k =116.8 α 95 =3.3°. This almost identical those other associated intrusions. angular dispersion site directions for only 6.5°, suggesting short time emplacement cooling. A second S, magnetite, titanomagnetite ilmenohaematite, present at most but bigger proportions as Limpopo Zambezi Belts approached. Considerations such geographical distribution, geology suggest S an overprint. Its ( ≈195°, ≈10°) similar that ∼ 1100 Ma Umkondo dolerites it suggested was introduced chemically or before onset Pan-African activity region. Of carries P component, three have been completely remagnetized. At these Z detected which may 650 ago. suggests this section, accompanying Musengezi Complex were late orogenic phase Belt.