A palaeomagnetic study of the lower part of the Palaeoproterozoic Waterberg Group, South Africa

Paleomagnetism of the lower two unconformity-bounded sequences of the Waterberg Group, South Africa: Towards a better-defined apparent polar wander path for the Paleoproterozoic Kaapvaal Craton.

“…Maré et al (2006) also observed this pervasive lightning signature among their sites within the same intrusion. Anomalously high coercivities revealed during demagnetization and the randomly scattered nature of directions point to lightning strikes as the possible cause of the poor quality of the results.…”

“…When steep, it is parallel to the present geomagnetic field at the sampling localities, but Hanson et al (2004a) attributed this direction to remagnetization during the Umkondo igneous event at ~1.1 Ga. Note that the INT direction cannot be distinguished from the direction obtained by Maré et al (2006) from red beds of the Swaershoek and Wilgeriver Formations, and that those authors rightly interpreted it as being a magnetic overprint. The paleomagnetic pole for the INT component is straddled by the poles of the Pilanesberg dykes (Gough, 1956) and that of the Premier kimberlite cluster (Doppelhammer and Hargraves, 1994) and 1244 ± 30 Ma (Onstott et al, 1986) Namaqua Eastern Zone combined pole (Evans et al, 2002).…”

“…Morgan and Briden (1981) also sampled red beds and acid volcanics in the Rust de Winter outlier. Maré et al (2006) could not, however, rule out overprinting at another stage. A recent study (Maré et al, 2006) investigated the paleomagnetism of the Swaershoek (Nylstroom region) and Wilgeriver (Middelburg area) Formations, and also of post-Waterberg dolerite intrusions.…”

“…The Nzhelele Formation supersedes lavas of the Sibasa Formation that are tentatively correlated with post-Waterberg dolerite at ~1.88 Ga Ma (Hanson et al, 2004a); thus W2 should in fact post-date both W1 and W3. A recent study (Maré et al, 2006) investigated the paleomagnetism of the Swaershoek (Nylstroom region) and Wilgeriver (Middelburg area) Formations, and also of post-Waterberg dolerite intrusions. Whereas the acid volcanics yielded no significant mean directions, the red beds did yield a characteristic component with intermediate-level demagnetization spectra, directed between W1 and W2.…”

Impact cratering — fundamental process in geoscience and planetary science

“…commun. ; also Maré et al 2006). A thick spherule layer in southern Greenland of about 1.8-2.0 Ga age was tentatively linked with either the Vredefort impact or with the Sudbury event (Chadwick et al 2001).…”