Gamma-activation determination of nitrogen in silicates in degassing studies of the Earth's mantle

The gamma-activation method was used for the determination of nitrogen in alumosiicates. This determination was based on the reaction 14N(gamma, n)13N. The samples were irradiated by a microtrone at the Institute of Physical Problems, Russian Academy of Science. The radiation intensity of this microtron ensured the required analytical characteristics of the method: the detection limit was 0.2 μg of nitrogen, and the error was 10-15 rel% for determination of 10-3-10-2 wt% of nitrogen. For the work on the processes of accumulation and redistribution of nitrogen in the rock-forming alumosilicate melt, its solubility was studied in natural basalts and synthesized albite at 1250 grad C and 3 kbar. The dependences of nitrogen solubility on the oxygen volatility and pressure were obtained (within 1-3 kbar in the presence of IW buffer [iron-(Fe)-wustite(FeO)] and an essential effect of the composition of the initial matrix was found