This dataset contains relative abundances and compound-specific carbon stable isotopic compositions of branched glycerol dialkyl glycerol tetraether (brGDGT) and branched monoalkyl glycerol tetraether (brGMGT) lipids as well as carbon stable isotopic compositions of total organic carbon (TOC) and total lipid extract (TLE). The data were obtained by extracting the lipids from modern peats (Sebangau area, Indonesia) and Miocene lignites (Morwell formation, Australia) and analyzing the extracts using high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS), spooling-wire microcombustion isotope ratio mass spectrometry (SWiM-IRMS), and elemental analysis-IRMS (EA-IRMS). The data were generated to the reconstruct the biological origin of brGDGT and brGMGT lipids and to deduce the carbon metabolism of the producing organisms.