what is the best methods to determine hydrothermal sulfide mineral, bulk carbonate,crystallised calcite and temperature conditions from sedimens as a proxy for hydrothermal alteration
Dear Dr. Olatunde,
the chemical composition of sediments is highly variable in terms of lithology and more so in terms of sediment chemistry. With this in mind I would not follow up this pathway as clue to the temperature of formation of any mineralization in sedimentary rocks.
I tested three methods:
1. Use organic matter/ coalified matter such as the vitrinite reflectivity. It is a good approach. Response to hydrthermal T changes retarded.
2. Phyllosilicates such as kaolinite-dickite-nacrite or the crystallinity of sheet silicates such as kaolinite, illite and smectite. Response to T change rather swift.
3. Heavy minerals (a wide range, e.g., baryte) and their grain morphologies (e.g. anatase). Direct response to T changes.
Excluding fluid inclusions studies of heavy minerals under point 3, minerals and OM referred to under points 2 and 3 are temperature estimates but no real geothermometers.
In case 1 you can calculate the formation temperature by an equation. I used it in one paper and it will help you to approximate the temperature of formation of the host sediments which you can under certain circumstances also apply to the mineralization (hydrothermal) in question.
Chemical approximations cannot achieve even this level reached under points 1 to 3.
Best regards
H.G.Dill
The fluid inclusion studies can be made on calcite and quartz and also stable isotope analysis for temperature determination. XRD analysis results show that mineralogical characterizations of the hydrothermal zones, and also alterations.
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