According to our thin sections that has been given from Basalt.our thin sections (Basalt) are that much fine grain that we cant recognize minerals from each other.in first step we think that can be a lava that injected between two layers as a sill. what is the best way for petrographic studies?
You have probably sampled from the outermost part of the basaltic lava. It is possible to find cases where phenocrysts do not show up in the basalts that come down very rapidly and volumetrically suddenly. I do not think you can get very good results under a polarizing microscope. I recommend that you go to other basalt samples, or carry out mineral chemistry and SEM studies.
Dear Mr. Rahimpour,
I suggest a “bimodal” approach. Firstly, carefully map the layer in question in context with the footwall and hanging wall rocks. Volcanic rock and volcaniclastic rocks do not appear “out of the blue sky” but form part of genetic sequence give there are no hiatuses. Secondly, try and use mineralogical methods such as XRD and SEM/WDX/EDX for a more detailed mineralogical and as far as the second method is concerned also a textural study. XRF of the whole rock renders the wheel come full circle. Considering these suggestions will certainly bring you a step forward and closer to the true nature of the fine-grained volcanic rocks or direct your thoughts to a different lithology.
I wish you much success H.G.Dill
XRD and EMP techniques can be applied on fine to very fine grained rocks like basalt, with the former for mineral identification and the latter for mineral chemistry.
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