Geochemistry of Archean shales from the Witwatersrand Supergroup, South Africa: Source-area weathering and provenance

Wronkiewicz, David J.; Condie, Kent C.

doi:10.1016/0016-7037(87)90293-6

Cited by 628 publications

(198 citation statements)

References 37 publications

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“…Previous research FIGURE 6 | Variation of grain size dependent magnetic parameters and Zr/Rb ratio of PC24 compare with relative sea level of the PRD (Fang et al, 1991) and clay (%) of ODP 1144 (Hu et al, 2012). suggested that variation of Zr and Rb within sediments was controlled by unitary factor (Wronkiewicz and Condie, 1987). Furthermore, Dypvik and Harris (2001) pointed out that Zr/Rb ratio of sediments might reflect the strength of wind carrying.…”

Section: Sensitive Magnetic Parameters To Climatic Variationmentioning

confidence: 92%

Sensitivity of Sediment Magnetic Records to Climate Change during Holocene for the Northern South China Sea

Ouyang

Zhao

et al. 2016

Front. Earth Sci.

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Section: Sensitive Magnetic Parameters To Climatic Variationmentioning

confidence: 92%

Sensitivity of Sediment Magnetic Records to Climate Change during Holocene for the Northern South China Sea

Ouyang

Zhao

et al. 2016

Front. Earth Sci.

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“…Durant l'altération, les études ont montré que le lessivage et la mobilité des éléments tels que le calcium, le sodium et le potassium sont proportionnels aux taux d'altération (Wronkiewicz & Condie 1987). Ces éléments sont préférentiellement lessivés (Nesbitt & Young, 1982).…”

Section: Evolution Chimiqueunclassified

Impact de l’alteration sur le bilan chimique des diatexites du Massif de l’Edough (Annaba, NE Algérien)

Hadjzobir¹

2012

Estud. geol.

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The studied section, located on the eastern part of the Edough massif (region of Annaba, Algeria), is characterized by a Mediterranean climate and the area is one of the most humid of Algeria (precipitation between 750 and 1200 mm/year). It consists of diatexites with homogeneous petrographic and metamorphic facies. The primary minerals are quartz, feldspar, oligoclase and biotite whereas weathering products are mostly represented by illite and montmorillonite. Although all samples comprise the same mineral composition, due to changes in the mode, the chemistry of this diatexites is very heterogeneous. The chemical analyses of the rocks reveal a progressive evolution in the composition in terms of gains and losses in Ca, Na, K, Fe, Mg and in trace elements. The values of the Chemical Index of Change (CIA = 62.79 - 68.32, of the Chemical index of Weathering (CIW = 63.92 - 70.79), the Freshness Index (IFRAIS = 76 - 46.35) and the high value of the loss of ignition (L.O.I > 2%) as well as the Rb/Sr ratio >1 indicate that the distribution of the chemical elements along the section is entirely controlled by weathering (bisiallitisation alteration type) during a long time.<br><br>[fr] La zone d’étude, constituée de diatexites, est située sur le flanc NE du massif de l’Edough (région de Annaba/ Algérie). Le massif, qui est l’un des plus arrosé d’Algérie (entre 750 et 1200 mm/an), se caractérise par un climat de type méditerranéen. Les diatexites montrent un faciès pétrographique et métamorphique homogène. Les minéraux primaires dominants sont le quartz, le feldspath potassique, l’oligoclase et la biotite alors que ceux d’altération sont représentés par des minéraux néoformés tels que la kaolinite, l’illite, la montmorillonite et dans une moindre mesure la séricite. A l’opposé de la minéralogie, la chimie des diatexites est hétérogène. Les analyses chimiques du matériel prélevé, du sommet vers la base des roches étudiées, révèlent une évolution progressive dans la composition chimique en terme de gains et pertes en Ca, Na, K, Mg, et en éléments traces. Les valeurs de l‘index d’altération chimique CIA varient de 62,79 à 68,32. Celles de l’index de météorisation (CIW) varient de 63,92 à 70,79 et les valeurs de l’index de fraîcheur (IFRAIS) de 76,15 à 46,35. Ces résultats, plus des pertes au feu élevées (P.F > 2%), ainsi qu'un rapport Rb/Sr >1 (en moyenne 1.74) montrent que la distribution des éléments chimiques est entièrement contrôlée par la météorisation et que les diatexites ont subi une altération de type bisiallitisation de longue durée, dominée par le lessivage de la roche primaire

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“…As the degree of weathering is a function chiefly of climate and rates of tectonic uplift (Wronkiewicz and Condie, 1987), increased chemical weathering intensity may reflect the decrease in tectonic activity and/or the change of climate towards warm and humid conditions which are more favorable for chemical weathering in the source region (Jacobson et al, 2003). Therefore, weathering indices of sedimentary rocks can provide useful information of tectonic activity and climatic conditions in the source area.…”

Section: Sediment Maturity and Weatheringmentioning

confidence: 99%

“…Values in bracket show mean element ratios and standard deviation. Wronkiewicz and Condie, 1987;McLennan, 2001). Particularly in the absence of sedimentary recycling, ratios such as Eu/Eu*, (La/Yb) N , La/Sc, Th/Sc, Th/Co, and Th/ Cr differ significantly in mafic and felsic source rocks and can therefore provide information about the provenance of sedimentary rocks (Cullers et al, 1988;Cullers, 1994a).…”

Section: Provenancementioning

confidence: 99%

Geochemistry of Middle Oligocene-Pliocene sandstones from the Nanpu Sag, Bohai Bay Basin (Eastern China): Implications for provenance, weathering, and tectonic setting

Shi-lin

Liu

et al. 2007

Geochem. J.

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Petrographic and geochemical compositions of thirty-seven Middle Oligocene-Pliocene sandstone samples from the Nanpu Sag in Bohai Bay Basin were analyzed to evaluate their provenance, weathering, and tectonic setting. These sandstones comprise mainly arkoses and lithic arenites and a few graywackes, characterized by low to moderate quartz/ total feldspar ratios (1.31-6.11, average 2.72 ± 0.98) and CIA values (45.87-70.13, 57.49 ± 5.93). The Middle-Upper Oligocene sandstones have average lower SiO 2 (71.72 ± 5.16%), and higher Fe 2 O 3 (3.06 ± 1.26%) and MgO (1.65 ± 0.39%), in contrast with the Miocene samples that generally have high SiO 2 (76.46 ± 4.26%) and low Fe 2 O 3 (3.04 ± 1.51%) and MgO (0.69 ± 0.32%) contents. Following the deposition, Fe 2 O 3 (3.17 ± 1.00%) and MgO (1.07 ± 0.38%) contents increased again in the Pliocene samples. Such a compositional variation trend is interpreted as a change of tectonic activity in the sag from Middle Oligocene to Pliocene, i.e., stronger in the Middle Oligocene, weaker in the Miocene and to stronger again in the Pliocene. Qt-F-L plot, trace element provenance discrimination diagrams (e.g., Eu/ Eu*, Co/Th, and La/Sc), and REE characteristics suggest that the source rocks were mainly derived from felsic igneous rocks, possibly from Mesozoic granitoids and felsic volcanic lavas in the Yanshan Fold Belt. Tectonic discrimination diagrams (e.g., SiO 2 -K 2 O/Na 2 O, Fe 2 O 3 * + MgO-TiO 2 , and Th-Sc-Zr/10) show that these sandstones were mainly deposited in an active continental margin setting, implying a remobilized intra-continental environment.

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Geochemistry of Archean shales from the Witwatersrand Supergroup, South Africa: Source-area weathering and provenance

Cited by 628 publications

References 37 publications

Sensitivity of Sediment Magnetic Records to Climate Change during Holocene for the Northern South China Sea

Sensitivity of Sediment Magnetic Records to Climate Change during Holocene for the Northern South China Sea

Impact de l’alteration sur le bilan chimique des diatexites du Massif de l’Edough (Annaba, NE Algérien)

Geochemistry of Middle Oligocene-Pliocene sandstones from the Nanpu Sag, Bohai Bay Basin (Eastern China): Implications for provenance, weathering, and tectonic setting

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