Precise reconstruction of variation in paleovegetation during Cretaceous hot period by analyses of terrestrial plant-derived organic molecules in sediments

本研究的目的是通过分析日本北海道白垩纪野佐群沉积岩中的陆源植物生物标志物和干酪根，重建古植被和陆地古环境的长时间尺度变化。特别是，通过分析陆地植物萜类生物标志物，我们发现被子植物/裸子植物植被比率和针叶植被迅速变化。此外，我们认为干酪根中抗性大分子释放的长链正构烷醇的组成可以作为落叶阔叶植物植被的指示物。利用干酪根释放的长链正构烷醇进行的古植被变化与利用陆地植物生物标志物进行的被子植物/裸子植物植被的变化几乎是同步的，证实了释放的正构烷醇替代物在从古代沉积物中重建古植被方面具有很高的适用性。

The objective of this study is to reconstruct long time scale variations in paleovegetation and terrestrial paleoenvironment by analyses of terrestrial plant-derived biomarkers and kerogens in sedimentary rocks from the Cretaceous Yezo Group, Hokkaido, Japan. In particular, we found rapid changes in angiosperm / gymnosperm vegetation ratio and coniferous vegetation evaluated by analysis of terrestrial plant terpenoid biomarkers. Moreover, we suggest that composition of long chain n-alkanols released from resistant macromolecule in kerogen can be useful as an indicator of deciduous broad leaf plant vegetation. Variation in the paleovegetation using the long chain n-alkanols released from kerogen is almost synchronous to that in angiosperm / gymnosperm vegetation using terrestrial plant biomarkers, confirming high applicability of the released n-alkanol proxy for reconstructing paleovegetation from ancient sediment.