Abstract: The data of n-alkane of lacustrine sediments in west of Sichuan prove the connection between the value of δ(¹³C) of C17-C22 n-alkane and the altitudes. The δ(¹³C) values of C17-C22 n-alkane increase along with the elevated altitude. According to the δ(¹³C) data, The relationship results from three key associated factors: partial pressure mospheric carbon dioxide p(CO₂), temperature and precipitation. The results also support the opinion that the δ(¹³C) value of C26-C33 n-alkane decrease along with the elevated altitude. Thus, comparing two aspects (n-alkane of longer and shorter train) mentioned above, it could be better to estimate the change of the altitude and the environment during the past time.

Key words: shorter train n-alkane, longer train n-alkane, single molecule carbon isotope, altitude, environment

摘要： 通过对四川盆地西部湖泊沉积物样品的单体烃碳同位素值的分析，发现短链烷烃的单体烃碳同位素值与海拔有一个较好的关系：海拔升高，短链烷烃的单体烃碳同位素值升高。通过对数据的分析，认为这种关系是由于大气中二氧化碳分压、温度、降水量等几个环境因素协同作用的结果。另一方面，检验了过去人们对于长链烷烃的认识，随着海拔的升高，长链烷烃单体烃碳同位素值变小。这两方面的对比可以更好地预测海拔变化和环境变化。

关键词: 短链烷烃, 长链烷烃, 单体烃碳同位素, 海拔, 环境