Which are the rocks or minerals being studied by you for the present work?
Dear Mr. Sengupta,
autoradiography can be used for all kinds of minerals from radioactive fetid fluorite , through zircon to pitchblende.
What is you rstudy aimed at ?
H.G.Dill
I am studying monazites and xenotime from beach placers using auto-radiography at present. We already have a reasonable good data base on these deposits using thin section studies based on microscopy followed by Electron Microprobe analysis on some of these samples, coupled to geochemical analysis using ICP (MS) and HpGe for thorium and uranium concentration measurements. Presently we would like to understand the process and nature of 'metamictization' in the Monazites and possibly Xenotime.
Dear Debashish, Xenotima, in general, does not occur associated with monazite. The metamictization of these ores promotes the total or partial destruction of the crystalline network due to the bombardment of radioactive waves that generates structural variations that are reflected in the luminescent behavior of the samples.
Dear Mr. Sengupta,
metamictization is a process which has in principle nothing to do with the environment of deposition in placer deposits where heavy minerals from multiple source rock areas may be washed together without showing any genetic interrelation with each other. You can, however, carry out radiometric age dating of single grains and also determine the trace element content of each grain. The question still is, what is the result you are going to expect with this method.
H.G.Dill
The studies on metamictization in Monazites is for studies related to the process of defect creation since the formation of the Monazites from the magma. We should be able to have the age estimation of the Monazites has we have the requisite facilities. The results of metamictization coupled to modelling studies would be useful in providing insight for designing of geological waste repository primarily for nuclear waste.
We are using OSL dating for quantification of the ages of the last marine transgression in the area under study. Some of our earlier studies are already there in RG if the readers are interested.
An additional aspect to be mentioned is that the studies on Monazites refer to their formation during erosion of the host rocks primarily due to marine transgression and regression and the action of the rivers and their tributaries. In these beach (heavy) mineral placers both Monazites and Xenotime are reported.
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