Age of carbonatite and phoscorite magmatism of the Phalaborwa Complex (South Africa)

Eriksson, S. C.

doi:10.1016/0009-2541(84)90172-4

Cited by 20 publications

(22 citation statements)

References 12 publications

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“…Neither of these hypotheses has any supporting evidence, and it must be considered that these units are essentially coeval. The conclusion from the data that the carbonatites are coeval with their host foyaites is supported by a recent study of the Phalaborwa complex (Eriksson 1984), which found that the time of emplacement of carbonatites and associated undersaturated rocks was the same within 10 Ma.…”

Section: Discussionsupporting

confidence: 51%

Geochronology of the Big Spruce Lake alkaline intrusion

Cavell¹,

Baadsgaard²

1986

Can. J. Earth Sci.

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A zircon age of 2188:;; Ma has been determined for the silica-saturated syenites of the Big Spruce Lake alkaline complex.Pb-Pb whole-rock ages of 2165' :; and 2155 + 16 Ma were obtained for the silica-undersaturated rocks of the complex and for the complex as a whole, respectively. The Sm-Nd whole-rock data yield an age of 2183 + 75 Ma for the complex as a whole. By weighting the ages by the inverse square of the standard deviations, an average age for the complex of 2174 + 20 Ma is determined. However, it is felt the zircon age is the most reliable for the time of crystallization of the complex. Minor contamination by country rock (Sm-Nd model ages of 2467-2595 Ma) and metasomatism contribute to scattered Sm-Nd data points and large errors in the ages obtained for the five individual units. The Pb-Pb data enable a limiting estimate of about 50 Ma for the maximum time span for the intrusion of centres 1-4. Les syknites satukes en silice du complexe alcalin du lac Big Spruce ont Ctk datCes avec le zircon i 2188:;; Ma. Un bge Pb -Pb sur roche totale de 2165' :; Ma a CtC obtenu pour les roches sous-satukes en silice du complexe, et de 2155 + 16 pour le complexe en tant qu'une entitC. Les ksultats de I'analyse Sm-Nd sur roche totale foumissent un bge de 2183 f 75 Ma pour l'ensemble du complexe. Une pondCration des bges par la mCthode de la r6ciproque de la racine c a h e des Ccarts-types accorde au complexe un bge moyen de 2174 + 20 Ma. Cependant, nous croyons que l'bge dCterminC sur zircon est le plus fiable pour le temps de cristallisation du complexe. Une contamination mineure par la roche encaissante (bges de 2467 -2595 Ma fondCs sur le mdele Sm-Nd) et une activitC mCtasomatique ont contribuC i la dispersion des points Sm-Nd sur la courbe et aux erreurs importantes dans les bges des cinq unitks individuelles. Les rksultats Pb -Pb permettent d'Cvaluer h une duke maximum de 50 Ma la mise en place de l'intrusion des centres 1-4.[Traduit par la revue]Can.

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Section: Discussionsupporting

confidence: 51%

Geochronology of the Big Spruce Lake alkaline intrusion

Cavell¹,

Baadsgaard²

1986

Can. J. Earth Sci.

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“…The age of the Palabora complex is essentially the same as that of the Bushveld Igneous Complex (2030 ± 18 Ma; Eriksson 1984), and thus it can be viewed as a manifestation of the same episode of hotspot activity that gave rise to the Bushveld. The Bukusu carbonatite complex in Uganda contains small amounts of chalcopyrite (Baldock 1969), but the Palabora deposit is unique as a major carbonatite-related copper resource.…”

Section: Metal Deposits Related To Carbonatitesmentioning

confidence: 99%

Metal Deposits in Relation to Plate Tectonics

Sawkins¹

1990

Minerals and Rocks

170

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“…Our oldest (U‐Th)/He dates are for the baddeleyite, which record cooling following Phalaborwa emplacement at 2.06 Ga, as constrained by previous geochronologic data (Eriksson, ; Heaman, ; Heaman & LeCheminant, ; Reischmann, ; Wu et al, ). The oldest titanite date is ∼1.1 Ga.…”

Section: Discussionmentioning

confidence: 86%

“… (a) Simplified geologic map of southern Africa displaying the extent of the Kaapvaal craton, younger accretionary belts, and major Proterozoic magmatic activity. (b) Geologic map of the Phalaborwa carbonatite complex, modified after Eriksson (), with sample locations. See text for additional sample information.…”

Section: Introductionmentioning

confidence: 99%

Deciphering a 2 Gyr‐Long Thermal History From a Multichronometer (U‐Th)/He Study of the Phalaborwa Carbonatite, Kaapvaal Craton, South Africa

Baughman

Flowers

2018

Geochem Geophys Geosyst

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(U‐Th)/He data were obtained for four minerals (baddeleyite‐BHe, titanite‐THe, zircon‐ZHe, apatite‐AHe) from the 2.06 Ga Phalaborwa carbonatite complex and nearby Archean basement of the Kaapvaal craton, South Africa. Our goals are to evaluate the relative He temperature sensitivities of these phases, better understand how radiation damage and other factors affect them, and inform aspects of the craton's thermal history. BHe dates overlap with Phalaborwa emplacement and record the highest temperatures of the dated phases. THe dates are 700–1,100 Ma and display a limited negative date‐eU correlation. ZHe dates are negatively correlated with eU, are younger (561–32 Ma) and have higher eU than the THe data, with the highest‐eU grains younger than the AHe dates. AHe dates are reproducible with a mean of 107 ± 7 Ma. The THe and ZHe data show radiation damage reduction of their He retentivities manifested as the negative date‐eU correlations. Alpha dose estimates for zircon are several orders of magnitude higher than for titanite, consistent with the ZHe dates recording lower temperatures and a younger portion of the history than the THe dates. Thermal history modeling yields time‐temperature paths that (1) explain the AHe, ZHe, and THe data while honoring existing geologic constraints, thus demonstrating the internal consistency of the data set, (2) imply possible reheating during Namaqua‐Natal orogenesis, and (3) limit maximum probable temperatures to ∼180°C during 300–183 Ma Karoo basin burial. The results show that exploiting multiple (U‐Th)/He thermochronometers and radiation damage effects can provide new insights into long‐term craton evolution.

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Age of carbonatite and phoscorite magmatism of the Phalaborwa Complex (South Africa)

Cited by 20 publications

References 12 publications

Geochronology of the Big Spruce Lake alkaline intrusion

Geochronology of the Big Spruce Lake alkaline intrusion

Metal Deposits in Relation to Plate Tectonics

Deciphering a 2 Gyr‐Long Thermal History From a Multichronometer (U‐Th)/He Study of the Phalaborwa Carbonatite, Kaapvaal Craton, South Africa

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