| Research Abstract |
This abstract report describes the analytical result of the paleo-environment from the sediment of the offshore of California (ODP Leg 167, Site 117E), especially with using the idex of lignin.
While the total concentration (V : vanillyl + S : siringyl + C : cinnamyl) of lignin is high (an average of 960 μg/g-C) with large variation (500-1800 μg/g-C) in the glacial age (Pleistocene), it is stable low average of 400 μg/g-C) in the Holocene. The both concentrations of vanillyl and syringyl are largely changed similar with total lignin at the glacial age, and they are changed little at the Holocene. Moreover, since the S/V ratio increases gradually from about 15 ka ago, this result shows clearly that contribution of angiosperm becomes largely at the Holocene. Since Heusser (1998) shows that the pollens of angiosperms (oak and chaparral) decrease relatively from 23 ka ago and those of gymnosperms (pine and juniper) decrease relatively from 15 ka ago in other sediment of this sea area, our results is consistent with the results of Heusser (1998).
The concentration of cinnamyl (Pc : p-coumaric acid and Vc : ferulic acid) is high at the glacial age, and is low at the Holocene similar with other lignin. Since the ratio of Pc/Vc is over 1.0 all over the age, the ratio is larger than the ratio (0.94) of herbaceous plant by Goni and Hedges (1992). From this result, the high Pc/Vc ratio suggests to be contributed from other source having high Pc/Vc ratio. Then, we analyzed six pollens including two species of pines by the TMAH method. Consequently, the Pc/Vc ratios of pines are found to be over 18, because they are rich in Pc, especially. This result suggests that the glacial age (〜10 ka ago) with high Pc/Vc ratio is affected by the pollens of pines.
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