Isotope variations and isotope effects of nitrogen in magmatic rocks

According to data taken from literature and obtained from measurements the delta 15N values of magmatic rocks range from -16 to +31 parts per thousand and the nitrogen concentrations from 1 to 142 parts per thousand and acid rocks between -15.6 and +30.9 parts per thousand. Correlations were found between the logarithm of nitrogen concentrations and 15N values. On the assumption that nitrides are involved in the isotopic exchange in the lithosphere and are possibly the dominant nitrogen compounds in the upper mantle, conclusions could be drawn with regard to the causes of isotope variations of nitrogen in the crust and mantle