Hydrogen isotope ratios were measured on terrigenous alkanes (n-C 25 to n-C 31 ) extracted from recent lake surface sediments from the climatically and environmentally distinct basins Qiangyong Glacier Lake, Yamzho Lake, Nam Co Lake, Keluke Lake and Xiao Qaidam Lake along a S-N transect in the Tibetan Plateau to explore the climatic implication of these biomarkers. δD values of these n-alkanes are compared to that of precipitation spanning a wide range from -167‰ to -51‰ and clearly correlate with δD values of meteoric water, indicating that terrigenous alkanes record the precipitation signal. The fractionation between precipitation and n-C 25 , n-C 27 alkanes cover a range from -45‰ to -70‰ whilst that between precipitation and n-C 29 , n-C 31 alkanes varies from -70‰ to -95‰, both being fairly constant along the S-N Tibetan transect with the mean at -57‰ and -82‰ respectively. By comparison with the fractionation of -130‰ along the S-N European transect, it implies that the hydrogen isotopic fractionation between meteoric water and terrestrial n-alkanes along the Tibetan transect represent distinct character.

The hydrogen isotopic composition (δD) of leaf water used for biosynthesis of n-alkanes can be modified by climate. Therefore, the δD can be considered as potential paleoclimatic proxy to explore. We compared measured δD values of alkanes (n-C 25 to n-C 31 ) extracted from a short sediment profile spanning the past 50 years with a 7-year resolution from Lake Yamzho, southern Tibetan Plateau. Climatic control was reconstructed using meteorological records of the nearby Langkazi and Lhasa weather stations. We found that the δD values of the n-alkanes correlated with the mean annual air temperature and significantly correlated with the mean growing season air temperature. On the other hand, the δD values show poor correlations with both rainfall amount and relative humidity. These results indicate that stable isotope composition of n-alkanes could be an excellent proxy for paleotemperature reconstruction.