Lower Paleozoic marine sedimentary rocks in Tarim Basin are characterized by the distribution of biomarkers coming from algae and bacteria

including the distribution of lower carbon number n-alkanes with even carbon predominances or odd carbon predominances and the distribution of lower carbon number alkyl cycloalkanes with even carbon predominances. Gammacerane

aarotanes

pristane and phytane are widespread

and the contents of rearrange steranes are lower than that of regular steranes

but the contents of tricyclic terpanes are higher. Cambrian sedimentary rocks with besin marginal facies are different from Ordovician Sedimentary rocks with open platform and half-deep water shelf facies in the distribution of biomarkers. The contont of C

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sterane increases from Cambrian to Ordovician. Ordovician sedimentary rocks in Tarim Basin are different from those of shallow water shelf facies in North American in the distribution of biomarkers. The later have no pristane and phytane

containing lower carbon number n-alkanes with odd carbon predominances and lower carbon number a1kyl cycloalkanes with odd carbon predominances

and are characetrized by higher content of C

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sterane

the content of rearrange steranes is equal to the content of regular steranes.