Podcast Beta
Questions and Answers
What is the difference between congruent and incongruent weathering, and how does it affect the formation of secondary minerals?
Congruent weathering occurs when the weathering of a mineral results in the formation of secondary minerals with the same chemical composition. Incongruent weathering occurs when the weathering of a mineral results in the formation of secondary minerals with a different chemical composition. Most silicate minerals undergo incongruent weathering and form secondary minerals such as clays.
What is the relationship between erosion rate and silicate weathering in riverine systems?
When the erosion rate is high, the rate of silicate weathering is mainly controlled by climatic variables.
What are the differences between evaporite and carbonate terrains, and what are the characteristic dissolved ions in each?
Evaporite terrains have a high TDS (>250mg/L) and a high ionic strength with ΣmZ+ >3000ueq/L. Dissolved ions in evaporite terrains are derived from the weathering of evaporites such as MgSO4 and NaCl, as well as CaCO3. Evaporite terrains have a 1:1 ratio of Na:Cl from halite, and 1:1 ratios following MgSO4 and CaCO3 dissolution (Mg, Ca, HCO3, SO4). In contrast, carbonate terrains have a TDS of 40-250mg/L and characteristic dissolved ions of low Na, and high Ca, Mg, HCO3- and SO42- from the weathering of carbonates, pyrite, and minor evaporites.
