The role of trace minerals in chemical weathering in a high-elevation granitic watershed (Estibère, France): chemical and mineralogical evidence

Chemical weathering in the Krishna Basin and Western Ghats of the Deccan Traps, India: Rates of basalt weathering and their controls

“…The maximum Ca contribution from carbonates is ϳ29% for the rivers used in calculation This is unlike granites/ gneiss watersheds, where Ca supply from such minor phases are reported to be more significant (Blum et al, 1998;White et al, 1999;Oliva et al, 2004). This difference is attributable to high Ca in basalts, relative ease of their weathering, and their relatively low carbonate content.…”

“…It has been shown in some of the earlier studies on granite watersheds (Blum et al, 1998;White et al, 1999;Jacobson et al, 2002;Oliva et al, 2004) that Ca-rich minor phases such as calcite, apatites, and Ca-rich silicates present in these rocks can be a major source of Ca to rivers draining them. The role of such phases in contributing to Ca budget of Deccan rivers is evaluated below.…”

A geochemical modelling study of the evolution of the chemical composition of seawater linked to a "snowball" glaciation

“…We use a standard silicate weathering law, where Ca 2+ and Mg 2+ weathering rates are proportional to global runoff and depend on mean global air temperature (Oliva et al, 2004), assuming that the present silicate weathering consumes 13.2×10 12 moles of atmospheric carbon per year (Dessert et al, 2003;Gaillardet et al, 1999). Continental carbonate weathering is proportional to global runoff times the concentration of Ca 2+ in equilibrium with calcite minerals and atmospheric CO 2 at the calculated mean air temperature (Donnadieu et al, 2006).…”

Sr isotopic characteristics in two small watersheds draining silicate and carbonate rocks: implication for studies on seawater Sr isotopic evolution

“…silicate rocks" (with a drainage area < 10 km 2 ) are referenced (Edmond et al, 1994;White and Blum, 1995;Oliva et al, 2003). The ratios are 0.2 to 1.0 for Ca/Na, 0.15 to 0.5 for Mg/Na, 0.1 to 0.3 for K/Na, 0.002 to 0.004 for Sr/Na, and 0 for Cl/Na and NO 3 /Na (Wu et al, 2013;Table 6).…”

“…Although the distributed area of carbonate rocks is only < 5 % of the drainage area, it has a disproportionately important contribution to the Sr in the Xishui River (average 19 %), which is consistent with the conclusion of the studies of the major ions (Wu et al, 2013). Previous studies have indicated that trace calcite in small watersheds draining silicate rocks could contribute a large proportion of the major ions in the river (Blum et al, 1998;Jacobson et al, 2002b;Oliva et al, 2004). As the 87 Sr/ 86 Sr ratios of silicate rocks in the Xishui River catchment are very close to those of Paleozoic carbonate rocks in the Yangtze Platform (Table 4), even if the contribution to Sr from carbonate weathering far exceeds its distributed area, it still has no obvious decreasing influence on the 87 Sr/ 86 Sr ratios of the river water.…”