BIOLOGICAL MARKERS APPLICATION IN STRATIGRAPHIC DIVISION AND CORRELATION - TAKE LOWER PALEOZOIC STRATA IN TARIM BASIN AS EXAMPLE.

Biomarkers are stable compounds of carbon- carbon skeleton in the sedimentary rocks or oil, and are usually used in oil correlation and palaeosedimentary environment restoration. An attempt to use biomarkers to divide and correlate strata is made in the paper. The studies show that the regular sterane distribution Of the Cambrian-Low Ordovician in the Tarim Basin was quite different from that of the Middle-Upper Ordovician. The former shows a C28 sterane content higher than the latter, and the regular sterane has an inverted "L" pattern distribution of C29>C28>C27. The latter has a C27 sterane content higher than the former and the sterane has a "V" pattern distribution of C29>C27>C28. The sterane distribution of Cambrian- Lower Ordovician and the Middle-Upper Ordovician changed from the inverted "L" into a "V" pattern, showing that during the evolutionary process of organisms, the organic origin & chemical structure components obviously changed. This may be used in the Lower Paleozoic stratigraphic division and correlation in the Tarim Basin. [ABSTRACT FROM AUTHOR]