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![A plot of Eu/Eu* vs. Ce/Ce* for shales from the Gamagara/Mapedi Formation. Also shown (open square) are those values for the reworked materials (red shales), laterite, and basalt of the lateritic weathering profile that developed in the Hekpoort Basalt of the Pretoria Group (data are from Yang and Holland, 2003). Error bars indicate ±1σ values. Eu/Eu*PAAS = [Eusample/EuPAAS]/[(Smsample/SmPAAS + Gdsample/GdPAAS)/2] and Ce/Ce*PAAS = [Cesample/CePAAS]/[(Lasample/LaPAAS + Prsample/PrPAAS)/2]. The Eu/Eu* and Ce/Ce* values for PAAS (cross symbols) are 1 by definition.]()
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![The stratigraphic subdivision of the newly proposed Keis supergroup. Note the inclusion of the Lucknow- and Mapedi formations with the lower part of the Keis supergroup and the regional unconformity at the base of the Mapedi Formation that separates the Keis supergroup from the Transvaal Supergroup in the Northern Cape Province of South Africa.]()
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![Comparisons of (a) (c) major and (b) (d) minor/trace element compositions between laterite (ferricrete) vs. directly overlying reworked materials (red shales) of the lateritic weathering profile that developed in the Hekpoort Basalt of the Pretoria Group (stratigraphic equivalent of the Ongeluk basalt underlying the Gamagara/Mapedi Formation; see Figure 2; Beukes et al., 2002), and those between the lower section red shales of the Gamagara/Mapedi Formation vs. the reworked materials of said weathering profile. Units used: (a) (c) [weight %] and (b) (d) [ppm]. Error bars indicate ±1σ values. Data of the Hekpoort weathering profile are from Yang and Holland (2003).]()
![Comparisons of (a) major (weight %) and (b) minor/ trace element (ppm) compositions between the upper and lower section samples of the Gamagara/Mapedi Formation. Error bars indicate ±1σ values.]()
![Plots of (a) Corg vs. Nbulk contents and (b) Corg contents vs. δ13Corg values of shales from the Gamagara/Mapedi Formation.]()
![A plot of Th/Sc weight ratios vs. Al2O3/TiO2 weight ratios of shales from the Gamagara/Mapedi Formation. A positive correlation exists for the lower section samples (R = 0.99).]()
![Plots of (a) Na/Al vs. K/Al (molar ratios) and (b) CIA vs. SiO2/Al2O3 (weight ratios) of shales from the Gamagara/Mapedi Formation. In both plots, the PAAS of Taylor and McLennan (1985) is shown for comparison.]()
![Depth profiles of (a) Al2O3/TiO2 weight ratios and (b) Th/Sc weight ratios of shales from the Gamagara/Mapedi Formation. Dashed lines represent (a) boundaries among mafic, intermediate, and felsic rocks as source materials of the shales and (b) PAAS (Taylor and McLennan, 1985).]()
![A plot of P2O5 vs. CaO contents of shales from the Gamagara/Mapedi Formation. The line represents the P2O5/CaO ratio of apatite [Ca5(PO4)3OH, i.e., Ca: P = 5:3]. The composition of PAAS (Taylor and McLennan, 1985) is also shown.]()
![Schematic representation of a measured profile (section line A-A’ in Figure 11) on Voëlwater 480 indicating the transition between the Transvaal Supergroup (Griqualand West Sequence of SACS, 1980) and the newly proposed Keis supergroup. The base of the Keis supergroup is the unconformity at the base of the Mapedi Formation. Total thickness of this section is ~2 200 m (corrected for dip and topographic effect). Insert photographs show the contact between the Lucknow Formation of the Transvaal Supergroup and the Neylan formation of the Keis supergroup.]()
![Comparisons of PAAS-normalized REY (rare earth and yttrium) contents of shales of the Gamagara/Mapedi Formation. PAAS: Post-Archean Average Shale of Taylor and McLennan (1985). (a) the upper section (SA-7 through SA-13); (b) the lower section (SA-14 through SA-17); and (c) pairs of Fe-rich red shales and Fe-poor white shales (SA-9r and SA-9w: open circle; SA-16r and SA-16w: open diamond).]()
![Plots of Al2O3/TiO2 weight ratios vs. δ56Fe values of shales from the Gamagara/Mapedi Formation. A shaded band represents the δ56Fe value of 0.00±0.05‰ for igneous rocks and Corg-poor sedimentary rocks (Beard et al., 2003). Also shown is the PAAS of Taylor and McLennan (1985), assuming a (Corg-poor shale) δ56Fe value = 0‰ (Beard et al., 2003).]()
![Plots of Fe3+/Ti vs. Fe2+/Ti atomic ratios of shales from the Gamagara/Mapedi Formation. In (a), constant Fe3+/σFe ratios of 0.8, 0.5, and 0.2 (positive slopes) and constant σFe/Ti ratios of 17.0 and 7.2 (basalt of the Hekpoort Basalt and PAAS, respectively) are drawn. An arrow on the constant σFe/Ti (= 17.0) line indicates a trend of oxidative weathering on the basalt (or source rocks) where Fe2+-bearing minerals were quantitatively oxidized to Fe3+ without loss of Fe (see Ohmoto, 1996). In (b), the reworked materials (red shales) and the laterite of the lateritic weathering profile that developed in the Hekpoort Basalt are also plotted for comparison using a logarithmic scale for both axes.]()
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![Summary of new stratigraphic correlations for the Mapedi and Gamagara Formations in Griqualand West, South Africa. BR—Blackridge; Yellow—sandstone; yellow with black ellipses—conglomerate; green—basalt; dark red to khaki—red beds; red—banded iron formation; black—Mn-rich beds; light blue—carbonate; brown—diamictite.]()
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Journal Article
Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
Journal: South African Journal of Geology
Publisher: Geological Society of South Africa
Published: 01 June 2006
South African Journal of Geology (2006) 109 (1-2): 123–138.
...Kosei E. Yamaguchi; Hiroshi Ohmoto Abstract The occurrence of red shales in Precambrian sedimentary rocks has been used to infer the presence of free O 2 in the atmosphere. Red shale samples from the ~2.2 Ga Gamagara/Mapedi Formation of the Postmasburg Group, South Africa were analyzed...
FIGURES
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Image
![A plot of Eu/Eu* vs. Ce/Ce* for shales from the Gamagara/Mapedi Formation. Also shown (open square) are those values for the reworked materials (red shales), laterite, and basalt of the lateritic weathering profile that developed in the Hekpoort Basalt of the Pretoria Group (data are from Yang and Holland, 2003). Error bars indicate ±1σ values. Eu/Eu*PAAS = [Eusample/EuPAAS]/[(Smsample/SmPAAS + Gdsample/GdPAAS)/2] and Ce/Ce*PAAS = [Cesample/CePAAS]/[(Lasample/LaPAAS + Prsample/PrPAAS)/2]. The Eu/Eu* and Ce/Ce* values for PAAS (cross symbols) are 1 by definition.](https://gsw.silverchair-cdn.com/gsw/Content_public/Journal/sajg/109/1-2/10.2113_gssajg.109.1-2.123/2/s_123fig14.jpeg?Expires=2147483647&Signature=H6m1LK5SP3bglKKCERqoZTO4DM21zp04vMpdKMBDlgrRo53BY2GkT7E1LAIB6wu9q~BKgixQ~SxUSwKPjUyvb-Tg39xWREecKoVTq3SrvH5MksJ-GYoej80T6~yuIwClZOuR-IfPMypSnFZq01Xa8NA-Tut4PvG9jD--9TF3i03noZbHVxzUAEiGin9~Jdrn2t7rjPe8SPKH4J0Uz5fgoxnPQ1zfQ1rTmczx-KdfhmZZmGMW6BZu7as-uAF12Hpt~Nq2HAgbOzLorUMh7Oa~GUV5BWghtUb~zZw4IgAbAEWrEC78nirgNnC9vSCGJ-xrsiQ0yQifVya5v5~NBfz5EA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A plot of Eu/Eu* vs. Ce/Ce* for shales from the Gamagara/Mapedi Formation. ...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 14. A plot of Eu/Eu* vs. Ce/Ce* for shales from the Gamagara/Mapedi Formation. Also shown (open square) are those values for the reworked materials (red shales), laterite, and basalt of the lateritic weathering profile that developed in the Hekpoort Basalt of the Pretoria Group (data
Journal Article
A 1.25 Ga depositional age for the “Paleoproterozoic” Mapedi red beds, Kalahari manganese field, South Africa: New constraints on the timing of oxidative weathering and hematite mineralization
Journal: Geology
Publisher: Geological Society of America
Published: 28 October 2019
Geology (2020) 48 (1): 44–48.
... laterites, which indicate a highly oxygenated atmosphere and suggest hot and humid climatic conditions. The Mapedi and Gamagara Formations are undated east of the Blackridge thrust but were thought to be lithological correlatives of the ≥1.91 Ga Mapedi red bed sequence to the west. Here, we report a U-Pb...
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Image
The stratigraphic subdivision of the newly proposed Keis supergroup. Note t...
in Revised definition/outline of the Kheis Terrane along the western margin of the Kaapvaal Craton and lithostratigraphy of the newly proposed Keis Supergroup
> South African Journal of Geology
Published: 01 June 2019
Figure 10. The stratigraphic subdivision of the newly proposed Keis supergroup. Note the inclusion of the Lucknow- and Mapedi formations with the lower part of the Keis supergroup and the regional unconformity at the base of the Mapedi Formation that separates the Keis supergroup from
Journal Article
U-Pb evidence for a 2.15 Ga orogenic event in the Archean Kaapvaal (South Africa) and Pilbara (Western Australia) cratons
Journal: Geology
Publisher: Geological Society of America
Published: 02 October 2019
Geology (2019) 47 (12): 1131–1135.
...Birger Rasmussen; Jian-Wei Zi; Janet R. Muhling Abstract There is geological evidence for widespread deformation in the Kaapvaal craton, South Africa, between 2.2 and 2.0 Ga. In Griqualand West, post-Ongeluk Formation (ca. 2.42 Ga) and pre-Mapedi Formation (>1.91 Ga) folding, faulting...
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Image
![Comparisons of (a) (c) major and (b) (d) minor/trace element compositions between laterite (ferricrete) vs. directly overlying reworked materials (red shales) of the lateritic weathering profile that developed in the Hekpoort Basalt of the Pretoria Group (stratigraphic equivalent of the Ongeluk basalt underlying the Gamagara/Mapedi Formation; see Figure 2; Beukes et al., 2002), and those between the lower section red shales of the Gamagara/Mapedi Formation vs. the reworked materials of said weathering profile. Units used: (a) (c) [weight %] and (b) (d) [ppm]. Error bars indicate ±1σ values. Data of the Hekpoort weathering profile are from Yang and Holland (2003).](https://gsw.silverchair-cdn.com/gsw/Content_public/Journal/sajg/109/1-2/10.2113_gssajg.109.1-2.123/2/s_123fig10.jpeg?Expires=2147483647&Signature=peVkMD69Z812l-mODBvsTdDxh~lto3wHuwqsyfmSkzvlLR5p4BDrHhII0w3FBaG8b7av4xzO8ifs2ZPxROJjlrYBfdkonroZrBOJK4T17Ek9-q3rfnzWAoUw2BSu63lSAJn9nmYuLfhgDOQcq-SOqEz4SXPbARp3i11lSq56R7PUJBsxreLlSLeotZXK1om-5os7pjd1~jWMX~~r2n0cqfhQcC1xnh0Pawvcr6D2GdMs37jpugx0m3kGSmwqm4o6smDNpldwZ9nbDFzkC9i~BNBcYWMj3ibwjvI97v~ShUn3VX887vbXnFnsupAt0nR~pZYE9rkV7neTw09piTiXEQ__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Comparisons of ( a ) ( c ) major and ( b ) ( d ) minor/trace element compos...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
equivalent of the Ongeluk basalt underlying the Gamagara/Mapedi Formation; see Figure 2 ; Beukes et al. , 2002 ), and those between the lower section red shales of the Gamagara/Mapedi Formation vs. the reworked materials of said weathering profile. Units used: ( a ) ( c ) [weight %] and ( b ) ( d ) [ppm
Image
Comparisons of (a) major (weight %) and (b) minor/ trace element (ppm) ...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 3. Comparisons of (a) major (weight %) and (b) minor/ trace element (ppm) compositions between the upper and lower section samples of the Gamagara/Mapedi Formation. Error bars indicate ±1σ values.
Image
Plots of (a) C org vs. N bulk contents and (b) C org contents vs. δ ...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 6. Plots of (a) C org vs. N bulk contents and (b) C org contents vs. δ 13 C org values of shales from the Gamagara/Mapedi Formation.
Image
A plot of Th/Sc weight ratios vs. Al 2 O 3 /TiO 2 weight ratios of shales ...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 8. A plot of Th/Sc weight ratios vs. Al 2 O 3 /TiO 2 weight ratios of shales from the Gamagara/Mapedi Formation. A positive correlation exists for the lower section samples (R = 0.99).
Image
Plots of ( a ) Na/Al vs. K/Al (molar ratios) and ( b ) CIA vs. SiO 2 /Al 2 ...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 9. Plots of ( a ) Na/Al vs. K/Al (molar ratios) and ( b ) CIA vs. SiO 2 /Al 2 O 3 (weight ratios) of shales from the Gamagara/Mapedi Formation. In both plots, the PAAS of Taylor and McLennan (1985) is shown for comparison.
Image
Depth profiles of ( a ) Al 2 O 3 /TiO 2 weight ratios and ( b ) Th/Sc weig...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 7 Depth profiles of ( a ) Al 2 O 3 /TiO 2 weight ratios and ( b ) Th/Sc weight ratios of shales from the Gamagara/Mapedi Formation. Dashed lines represent ( a ) boundaries among mafic, intermediate, and felsic rocks as source materials of the shales and ( b ) PAAS ( Taylor and McLennan
Image
![A plot of P2O5 vs. CaO contents of shales from the Gamagara/Mapedi Formation. The line represents the P2O5/CaO ratio of apatite [Ca5(PO4)3OH, i.e., Ca: P = 5:3]. The composition of PAAS (Taylor and McLennan, 1985) is also shown.](https://gsw.silverchair-cdn.com/gsw/Content_public/Journal/sajg/109/1-2/10.2113_gssajg.109.1-2.123/2/s_123fig15.jpeg?Expires=2147483647&Signature=fJGbCMEtCRLBj13Sx3pOUjbDYyYVYZaJG6DfcMh~OLorlaLAhelvYwlQGEXy~hse~tlFnFO6ETl9mlnxxHCT5ahNQEyYSf4d9pRPNrXRzQNQHG1PCOiNRXMG7j18F~lbo4o2nCHmfhRReYsh-Gp4mIqjzQITnJ6-9EX4-j~PV9D6LnUimUJc9wgVnHYD~ITdk82dXhrSjMyOCWXAYYejfZA75fyJ3rsLd7Fq2TCH8sN2XBrkwZargxmQrJaJU8yp5VEJMVW4U9DYfikSziicxcPmoapOcrHdITbfSo~fVAMlu7ttyL4XoUoFc8Gc~QMZ0s9V7ir35-Gb6DBtoqoB4Q__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A plot of P 2 O 5 vs. CaO contents of shales from the Gamagara/Mapedi Form...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 15. A plot of P 2 O 5 vs. CaO contents of shales from the Gamagara/Mapedi Formation. The line represents the P 2 O 5 /CaO ratio of apatite [Ca 5 (PO 4 ) 3 OH, i.e. , Ca: P = 5:3]. The composition of PAAS ( Taylor and McLennan, 1985 ) is also shown.
Image
Schematic representation of a measured profile (section line A-A’ in Figur...
in Revised definition/outline of the Kheis Terrane along the western margin of the Kaapvaal Craton and lithostratigraphy of the newly proposed Keis Supergroup
> South African Journal of Geology
Published: 01 June 2019
is the unconformity at the base of the Mapedi Formation. Total thickness of this section is ~2 200 m (corrected for dip and topographic effect). Insert photographs show the contact between the Lucknow Formation of the Transvaal Supergroup and the Neylan formation of the Keis supergroup.
Image
Comparisons of PAAS-normalized REY (rare earth and yttrium) contents of sha...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 4. Comparisons of PAAS-normalized REY (rare earth and yttrium) contents of shales of the Gamagara/Mapedi Formation. PAAS: Post-Archean Average Shale of Taylor and McLennan (1985) . (a) the upper section (SA-7 through SA-13); (b) the lower section (SA-14 through SA-17); and (c
Image
Plots of Al 2 O 3 /TiO 2 weight ratios vs. δ 56 Fe values of shales from t...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 13. Plots of Al 2 O 3 /TiO 2 weight ratios vs. δ 56 Fe values of shales from the Gamagara/Mapedi Formation. A shaded band represents the δ 56 Fe value of 0.00±0.05‰ for igneous rocks and C org -poor sedimentary rocks ( Beard et al. , 2003 ). Also shown is the PAAS of Taylor
Image
Plots of Fe 3+ /Ti vs. Fe 2+ /Ti atomic ratios of shales from the Gamagara/...
in Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa
> South African Journal of Geology
Published: 01 June 2006
Figure 12. Plots of Fe 3+ /Ti vs. Fe 2+ /Ti atomic ratios of shales from the Gamagara/Mapedi Formation. In ( a ), constant Fe 3+ /σFe ratios of 0.8, 0.5, and 0.2 (positive slopes) and constant σFe/Ti ratios of 17.0 and 7.2 (basalt of the Hekpoort Basalt and PAAS, respectively) are drawn
Journal Article
Revised definition/outline of the Kheis Terrane along the western margin of the Kaapvaal Craton and lithostratigraphy of the newly proposed Keis Supergroup
Journal: South African Journal of Geology
Publisher: Geological Society of South Africa
Published: 01 June 2019
South African Journal of Geology (2019) 122 (2): 187–220.
...Figure 10. The stratigraphic subdivision of the newly proposed Keis supergroup. Note the inclusion of the Lucknow- and Mapedi formations with the lower part of the Keis supergroup and the regional unconformity at the base of the Mapedi Formation that separates the Keis supergroup from...
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Journal Article
Erratum
Journal: South African Journal of Geology
Publisher: Geological Society of South Africa
Published: 01 December 2006
South African Journal of Geology (2006) 109 (4): 637.
...: Yamaguchi, Kosei E. and Ohmoto, Hiroshi (2006). Geochemical and isotopic constraints on the origin of Paleoproterozoic red shales of the Gamagara/Mapedi Formation, Postmasburg Group, South Africa. South African Journal of Geology , 109 , 123–138. © 2006 December Geological Society of South...
Image
Summary of new stratigraphic correlations for the Mapedi and Gamagara Forma...
in A 1.25 Ga depositional age for the “Paleoproterozoic” Mapedi red beds, Kalahari manganese field, South Africa: New constraints on the timing of oxidative weathering and hematite mineralization
> Geology
Published: 28 October 2019
Figure 4. Summary of new stratigraphic correlations for the Mapedi and Gamagara Formations in Griqualand West, South Africa. BR—Blackridge; Yellow—sandstone; yellow with black ellipses—conglomerate; green—basalt; dark red to khaki—red beds; red—banded iron formation; black—Mn-rich beds; light
Journal Article
Seismic Stratigraphic Constraints on Neoarchean - Paleoproterozoic Evolution of the Western Margin of the Kaapvaal Craton, South Africa
Journal: South African Journal of Geology
Publisher: Geological Society of South Africa
Published: 01 June 2002
South African Journal of Geology (2002) 105 (2): 107–134.
... Ov: Volop Group Oh: Hartley Formation Oml: Mapedi and Lucknow Formations Transvaal Supergroup Pretoria Group Pm: Magaliesberg Formation Psds: Strubenkop, Daspoort and Silverton Formations Ph: Hekpoort and Dwaalheuwel Formations Pt: Timeball Hill and Boshoek Formations...
FIGURES
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