When it come to batch dissolution experiment (for water-rock interaction study), most authors have selected igneous rocks, sedimentary rocks and minerals formed under igneous conditions. Is there any special reason for that? Is there any article for the same experiment where metamorphic rocks were used?
Thank you
Dear Tharanga,
The rock type used depend on what one is trying to test/discover/show. Many researchers are interested in the Earth's carbon cycle, and how atmospheric CO2 is drawn down by rock weathering. So, they tend to use igneous rocks in simulated weathering studies. These rocks are used because they have not been through the weathering cycle and so might be expected to have a greater influence on CO2 drawdown than rocks that have - sediments.
If you want a better answer, you will have to refine your question.
Thanks John! Your contribution is highly appreciated.
If I ask the same question again in a different way, why metamorphic rock are not preferred water-rock interaction batch dissolution experiments? I did not see evidences for the point you made in all the articles I read.
Dear Tharanga,
All I can do, not having read the papers you have read, is say again that ones choice of rock depends on what one wishes to achieve with it. If the papers you read did not make clear why the rocks chosen were chosen, why not write to the authors and ask them why they did not use metamorphic rock?
For rock water interaction study lots of publications are available. For your information kindly go through
V.k.saxena and s.ahmed ,2001' Dissolution of fluoride in groundwater , a water rock interaction study. Environmental Geology, 40' 1084-1087.
There may be no specific reason why igneous rocks were used and metamorphic rocks were not used, and it may be that the application of the research was for an area with igneous rocks (without metamorphic rocks). I do not believe there are any specific water-rock interaction differences between igneous and metamorphic rocks. A metamorphic rock is a type of rock which has been changed by extreme heat and pressure. So, an igneous rock can become metamorphic by exposing it to heat and pressure. This heat and pressure typically dissolves and re-precipitates some of the minerals in the rock. So, there are some differences in types and chemistry of the minerals, and the morphology of the minerals may be different, which may impact dissolution. Hope that helps.
For water- rock interaction study in different rock types which includes, granite gneisses we have carried out some study and presented in :
V.K.Saxena and S. Ahmed 2003, Inferring the chemical parameters for the dissolution of fluoride in groundwater. Environmental Geology volume 43, number 6, page 731-737.
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