Short-lived magmatic activity in an anorogenic subvolcanic complex: 40Ar/39Ar and ion microprobe U–Pb zircon dating of the Erongo, Damaraland, Namibia

Long duration (>4 Ma) and steady-state volcanic activity in the early Cretaceous Paraná–Etendeka Large Igneous Province: New palaeomagnetic data from Namibia

“…Many 40 Ar/ 39 Ar estimates were obtained by the laser total fusion method, since found to produce misleading results (Thiede and Vasconcelos, 2010) and subsequently rendering numerous early estimates unreliable. The most recent synthesis by Janasi et al (2011) supports a ≈3 Myr timeframe for volcanic activity, yet also highlights the small number of reliable estimates (by 40 Ar/ 39 Ar step heating or U-Pb) that sample the extrusive stratigraphy (Ernesto et al, 1999;Janasi et al, 2011;Pinto et al, 2011;Renne et al, 1992Renne et al, , 1996bThiede and Vasconcelos, 2010) and overlying/intruding units (Wigand et al, 2004).…”

Structure of volcano plumbing systems: A review of multi-parametric effects

“…where a ring dyke formed only to the northwest of a SW-NE-striking regional fault passing through the caldera (Wigand et al, 2004). …”

Aeromagnetic mapping and reconnaissance geochemistry of the Early Cretaceous Henties Bay-Outjo dike swarm, Etendeka Igneous Province, Namibia

“…Associated with this bundle of dikes are the Damaraland intrusive complexes Kalkfeld, Etaneno, Paresis, Okorusu and, if the trend is extended south, the Erongo complex as well. The Kalkfeld complex has not been reliably dated but the others have similar ages: 134 ± 1.7 Ma for Paresis (U-Pb zircon: Pirajno et al, 2000), 134 ± 2.6 Ma for Etaneno (Rb/Sr, cited in Verwoerd et al, 2000), 126 ± 1.4 Ma for Okorusu ( 40 Ar-39 Ar isochron, Milner et al, 1995) and 132 ± 2 Ma for Erongo ( 40 Ar-39 Ar, U-Pb zircon, Wigand et al, 2004). There are no structural or lithologic features of the Damara Belt in this position that would readily explain the concentration of dikes and intrusive complexes, but it clearly represents a preferred zone for magma emplacement in the crust, and we consider it significant that the largest of the Damaraland complexes, Erongo, lies at the intersection of this zone with the Omaruru Lineament/Waterberg Fault.…”

“…The closest definitive exposures of Etendeka basalts are around the Messum complex (Fig. 1), but tholeiitic basalt flows at the base of the Erongo complex are thought to be outliers of the Etendeka basalts based on compositional similarity, and because they are geochemically distinct from the Erongo units (Pirajno, 1990;Wigand et al, 2004). The inference that flood basalts once covered the area of the HOD is also consistent with the results of an apatite fission-track study by Raab et al (2002), who concluded that post-Etendeka denudation was strongest in the Central Zone of the Damara Belt, where the dike swarm is primarily located.…”