Weathering geochemistry and Sr-Nd fingerprints of equatorial upper Nile and Congo muds
Article first published online: 21 FEB 2013
©2013. American Geophysical Union. All Rights Reserved.
Geochemistry, Geophysics, Geosystems
Volume 14, Issue 2, pages 292–316, February 2013
How to Cite
2013), Weathering geochemistry and Sr-Nd fingerprints of equatorial upper Nile and Congo muds, Geochem. Geophys. Geosyst., 14, 292–316, doi:10.1002/ggge.20060., , , , , and (
- Issue published online: 21 FEB 2013
- Article first published online: 21 FEB 2013
- Accepted manuscript online: 5 JAN 2013 12:00AM EST
- Manuscript Accepted: 27 DEC 2012
- Manuscript Revised: 20 DEC 2012
- Manuscript Received: 3 JUL 2012
All Supplementary Information may be found in the online version of this article.
|Africa_Mud_Appendix_A.doc||Word document||88K||Supporting Information|
|tA1.pdf||PDF document||23K||Synthetic description of sedimentary provinces identified in equatorial Africa. Provenance classification after Garzanti and Andò . Annual rainfall ranges from <1 m (dry) to ~2 m (hyperhumid).|
|tA2.pdf||PDF document||133K||Bulk mineralogy of the studied mud samples. X-ray powder diffraction analyses by Massimo Setti and Luigi Marinoni (University of Pavia). GSZ= grain size.|
|tA3.pdf||PDF document||34K||Clay mineralogy. X-ray powder diffraction analyses of the <2 µm class by Massimo Setti and Luigi Marinoni (University of Pavia).|
|tA4.pdf||PDF document||613K||Geochemistry of the studied mud samples. Elements analysed by aqua regia digestion (a.r.d.) may be underestimated because of only partial leaching of refractory minerals. Chemical weathering indices CIA, CIW, PIA, WIP are after Nesbitt and Young , Harnois , Fedo et al. , Parker , respectively. In order to avoid bias caused by hydraulic concentration of heavy minerals hosting Ti, REE and Th, aAl values were normalized to non-mobile Al; aAl values were calculated with reference to average Virunga [Rogers et al., 1992; 1998] and Kivu lavas [Furman and Graham, 1999] for purely volcaniclastic muds, to Kibaran and Singo granitoids [Fernandez-Alonso et al., 1986; Fernandez-Alonso and Theunissen, 1998; Nagudi et al., 2003] for purely plutoniclastic muds, and to UCC for all other samples. The Eu anomaly is the measured chondrite-normalized Eu value over the value that Eu would have in a linear extrapolation between chondrite-normalized values of Sm and Gd. The Ce anomaly Ce/Ce*, indicative of redox state, is the measured PAAS-normalized Ce value over the value that Ce would have in a linear extrapolation between PAAS-normalized values of La and Pr. MREE is the average of Eu, Gd, Tb and Dy normalized to PAAS, MREE* the average of LREE (La, Ce, Pr, Nd) and HREE (Er, Tm, Yb, Lu) values [Haley et al., 2004 and references therein]. The chondrite-normalized LaN/YbN, LaN/SmN, GdN/HoN, and HoN/YbN ratios are also given.|
|tA5.pdf||PDF document||518K||Geochemistry of the studied sand samples [for full petrological description and discussion of river sands in the same area see Garzanti et al., in review].|
|tA6.pdf||PDF document||27K||Element concentrations used for normalization and calculation of weathering indices. Data sources: 1) Rogers et al. [1992; 1998]; 2) Furman and Graham ; 3) Hildebrand , Fernandez-Alonso et al. , Fernandez-Alonso and Theunissen ; 4) Taylor and McLennan [1985; 1995], McLennan , Hu and Gao ; 5) Taylor and McLennan ; 6) McDonough and Sun .|
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