Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences and Gansu Provincial Key Laboratory of Petroleum Resources,Lanzhou 730000,China;
School of Earth Science&Resources,Chang’an University,Xi’an 710054,China;
Shaanxi Center of Mineral Geological Survey,Xi'an 710068,China;
freshwater lake sediment; n-alkane; simulation experiment; bacterial origin; hydrogen isotope; thermal evolution;