Abstract
Multiple reworking of ore deposits may disturb geochronologic systems and eventually render incorrect ages for ore deposition or different stages of ore formation. Micro-inclusions, may beprotected from later disturbances by their host mineral and thus, yield reliable age information. Major problems in dating micro-inclusions include their genetic connection with various stages of ore formation and technical aspects, such as loss of daughter isotopes by α-recoil and the initial isotopic composition of the daugher element. The problem of daughter-loss from a high-μ micro-inclusion (μ=238U/204Pb) by α-recoil can be avoided by analyzing the inclusion together with its low-α host. The philosophy behind the presented analytical approach is to “trade” radiogenic composition of the daughter element (i.e., high 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb) against closed-system behavior. This approach is demonstrated for <10 microns small uraninite inclusions in darkmica from Ehrenfriederdorf, Erzgebirge, Saxony. Our data demonstrate that micro-inclusions may yield precise and accurate age data for early ore forming processes.
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Romer, R.L., Thomas, R. (2005). U-Pb dating of micro-inclusions: The age of the Ehrenfriedersdorf tin deposit (Erzgebirge, Germany). In: Mao, J., Bierlein, F.P. (eds) Mineral Deposit Research: Meeting the Global Challenge. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-27946-6_208
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DOI: https://doi.org/10.1007/3-540-27946-6_208
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