Geochemistry of soils derived from black shales in the Ganziping mine area, western Hunan, China

Geochemistry of major and trace elements and Pb–Sr isotopes of a weathering profile developed on the Lower Cambrian black shales in central Hunan, China

“…The above elemental mobility during black shale weathering is similar to those concluded by many previous studies (e.g., Nesbitt and Young, 1982;Peng et al, 2004Peng et al, , 2009bFalk et al, 2006;Lavergren et al, 2009aLavergren et al, , 2009bYu et al, 2012;Xu et al, 2013). However, the most important we find in this study is that the major elements SiO 2 , Al 2 O 3 , MgO, FeO, CaO, K 2 O, Na 2 O, LOI, and trace elements Ba, Cs, Rb, Sr, U, Th, Sn, Sc, Ge and REE (Y), have the highest amount of leaching (with the lowest s values) occurring for the soil samples (D1-D4) of the DS horizon (Fig.…”

“…In contrast, the later stage of chemical homogenisation was accompanied by the further transformation of the weathered materials, which was very important for soil formation. The soils derived from black shales (Peng et al, 2005(Peng et al, , 2009bYu et al, 2009Yu et al, , 2012Tang et al, 2009;Xu et al, 2013) distributed in South China (Fig. 1a), in which the present climate is subtropical and controlled by the East Asian monsoon, might result from the above two geochemical processes.…”

“…carbon cycle (e.g., Petsch et al, 2000Petsch et al, , 2001Jaffe et al, 2002). The weathering of black shale has therefore received substantial research attention, especially the chemical changes during weathering (e.g., Littke et al, 1991;Jaffe et al, 2002;Xu et al, 2013). Such chemical changes are generally explained by mineral dissolution, secondary mineral formation, cation exchange and loss and gain of amorphous oxide phases ; and references therein), during which most metals, including Cd, Co, Mn, Mo, Ni, U, Zn, and PGE, are lost from shales (Peucker-Ehrenbrink and Hannigan, 2000;Jaffe et al, 2002;Peng et al, 2004;) and others are enriched in soils derived from the shales (e.g., Chon et al, 1996;Lee et al, 1998a;Pašava et al, 2003;Poň avič et al, 2006;Peng et al, 2009b;Tang et al, 2009;Yu et al, 2012;Xu et al, 2013).…”

Vanadium: Global (bio)geochemistry

“…As observed for coal, V in shale associates preferentially with the clay minerals (e.g., Peeacor et al (2000) and Lipinski et al (2003)). In one recent study, soils developed on V-enriched black shale were shown to retain the signature of high V concentration, and V in the soil was distributed more homogeneously than in the parent rock; the fresh shale had V concentrations ranging from 225-5162 mg kg 1 , and the soils from 187-442 mg kg 1 (Xu et al, 2013). The difference between the unweathered and weathered material was attributed to a two-stage differentiation process: 1) chemical differentiation, largely by leaching of more mobile chemical components, and 2) chemical homogenization, which includes hydrolysis of resistant silicate minerals as well as continued preferential leaching of some elements (Xu et al, 2013).…”

“…The reference shales may not, however accurately represent the sediments being studied ( Van der Weijden, 2002). Concentrations of V in shales span a wide range globally and can vary widely across local geographic areas (see Xu et al (2013) and Section 3.2).…”