Paleomagnetic results from some southern African kimberlites, and their tectonic significance

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Abstract
Paleomagnetic data are reported from kimberlite occurrences of three distinct age groups: (1) National (one pipe), D = 221°, I = −51°, k = 41, α95 = 7.2°, age ∼1140 m.y., (2) Swartruggens (three fissures), mean D = 293°, I = −46°, k = 22, α95 = 26,9°, age = ∼150 m.y., and (3) six bodies in and adjacent to Lesotho, D = 350°, I = −69°, K = 66, α95 = 8.3° with age spread of ∼90 + 5 m.y. Analysis of these and previously published data suggests that most individual kimberlite bodies give acceptable paleomagnetic (as distinct from virtual geomagnetic) poles. This leads to a revised apparent polar wander curve for Africa in upper Mesozoic time and suggests that the time of kimberlite emplacement does coincide with intervals of rapid plate motion, although this cannot be the primary cause of their intrusion.
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