TY JOUR TI Organic matter geochemistry of Quaternary sediments of the Seyda River valley (northeast of the Pechora Lowland) KW biomarker-hydrocarbons KW peat KW n-alkanes in peat KW peat pyrolysis products KW guaiacyl phenols KW aromatic triterpenoids JO Vestnik of geosciences AU Burdelnaya, N.S. AU Marchenko-Vagapova, T.I. AU Bushnev, D.A. PY 2026 IS 0 PB FSBI FIC "Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences"