Parallel pyrolytic studies were carried out on an immature, ultralaminae-rich, type I kerogen (Goynuk oil shale kerogen) and a related algaenan (isolated from the extant green microalga Scenedesmus communis). Isothermal, closed, pyrolyses were performed under argon, in sealed gold tubes, under various temperature/time conditions (ranging from 260 to 550 degrees C and 1 to 72 h). Nitrogen distribution was determined, through independent measurements, in the different fractions obtained from these pyrolyses. Such analyses allowed, for the first time to the best of our knowledge, to establish complete nitrogen mass balances for kerogen pyrolyses and to derive comparisons with an algaenan. Sulfur distribution in the pyrolysis products was examined as well. The nature and the abundance of the individual constituents of the gas fractions were also determined. The latter analyses provided information on (i) the timing of CO2, N-2, CH4, and H2S production, upon thermal stress, to be expected from ultralaminae-rich kerogens and source algaenans and (ii) the composition of the gas fractions which should be generated from such kerogens during the different stages of thermal, natural, maturation.