Carbonatite magmatism of the southern Siberian Craton 1 Ga ago: Evidence for the beginning of breakup of Laurasia in the early Neoproterozoic |
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Authors: | V B Savelieva Yu V Danilova E P Bazarova A V Ivanov V S Kamenetsky |
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Institution: | 1.Institute of the Earth’s Crust, Siberian Branch,Russian Academy of Sciences,Irkutsk,Russia;2.School of Earth Sciences,University of Tasmania,Hobart,Australia |
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Abstract: | Apatite and biotite from dolomite?ankerite and calcite?dolomite carbonatite dikes emplaced into the Paleoproterozoic metamorphic rock complex in the southern part of the Siberian Craton are dated by the U–Pb (LA-ICP-MS) and 40Ar–39Ar methods, respectively. Proceeding from the lower intercept of discordia with concordia, the age of apatite from calcite?dolomite carbonatite is estimated to be 972 ± 21 Ma and that for apatite from dolomite?ankerite carbonatite, as 929 ± 37 Ma. Values derived from their upper intercept have no geological sense. The ages obtained for biotite by the 40Ar–39Ar method are 965 ± 9 and 975 ± 14 Ma. It means that the formation of carbonatites reflects the earliest phases of the Neoproterozoic stage in extension of the continental lithosphere. |
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