Geochemistry and petrogenesis of the Tsirub nephelinite intrusions, southern Namibia

Nakashole, Albertina; Roex, Anton le; Reid, David L.

doi:10.1016/j.jafrearsci.2019.103701

Cited by 2 publications

(2 citation statements)

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“…The closest alkaline complex to the TCC is the recently described Tsirub nephelinite intrusions, ~20 km south of Dicker Willem and ~35 km ENE of the TCC (Nakashole et al 2020). The extent to which the carbonatites and alkaline complexes lie on a structural lineament (the NE-striking Luderitz lineament), possibly created during a period of Gondwanaland rifting and crustal extension, is uncertain (Reid et al 1990;Woolley, 2001;Alfonso et al 2022).…”

Section: Geological Settingmentioning

confidence: 99%

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A preliminary study of the rare earth element-enriched Twyfelskupje carbonatite complex, southern Namibia

Marlow¹,

Palmer

2022

Geol. Mag.

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The Twyfelskupje carbonatite complex, Southern Namibia, exhibits the typical igneous emplacement structures of carbonatites, including plugs, cone sheets and dyke stockworks. The excellent exposure allows for detailed studies of the high-level geochemical and structural evolution of the carbonatite, and the nature of the concomitant rare earth element mineralization. Radiogenic isotope analyses (Sr, Nd, Pb) reveal that, in common with many other carbonatites, the Twyfelskupje carbonatite complex appears to be predominantly derived from mixing between HIMU and EM1 mantle end-members. Following partial melting of these mantle sources, the geochemical and structural evolution of the Twyfelskupje carbonatite complex proceeded by a staged process involving separate magma pulses, a series of emplacement structures, sub-solidus crystallization, fractionation and low-temperature hydrothermal alteration. The dominant rare earth element minerals in the Twyfelskupje carbonatite complex are fluorcarbonates and monazite, and are characterized by variable Ca, high F and light rare earth elements in the order Ce>La>Nd. Comparison between the rare earth element concentrations of the whole rocks, dominant rare earth element minerals and carbonates suggests that ∼95 % of the total rare earth element abundance of the Twyfelskupje carbonatite complex is contained within fluorcarbonates and monazite. Overall, the early calcio-carbonatite plugs are rare earth element enriched (mean 4.47 wt % rare earth oxides) relative to the magnesio-carbonatite cone sheets (mean 2.51 wt % rare earth oxides).

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Section: Geological Settingmentioning

confidence: 99%

“…The Sr, Nd and Pb isotope ratios were measured on seven samples, and the data are listed in Table 5. The εNd(t) values are also given, assuming that the TCC was emplaced at the same time (~50 Ma) as the Dicker Willem carbonatite (Reid et al 1990) and the Tsirub nephelinite intrusions (Nakashole et al 2020).…”

Section: E Isotopesmentioning

confidence: 99%