四川盆地西缘地区上三叠统须家河组化石木年轮的古气候意义

四川盆地西缘上三叠统须家河组植物化石丰富，在最近的地质调查中新发现保存完好、年轮清晰的化石木。通过对化石木年轮的研究分析，初步探讨了四川盆地西缘晚三叠世须家河组沉积期的古气候特征。研究表明:须家河组沉积时期气候温暖，化石木中明显的年轮表明大气降水呈季节性波动，这与盛行于二叠纪至三叠纪的巨型季风密切相关；化石木的平均敏感度小于0.3，说明植物生长过程中年水分供给均衡；化石木年轮的早材带与晚材带宽度变化大，显示植物的生长受到了晚三叠世巨型季风的强烈影响。

Fossil Wood of the Upper Triassic Xujiahe Formation on the Western Margin of Sichuan Basin:Implication for Palaeoclimate

Abundant plant fossils were found in the Upper Triassic Xujiahe Formation outcropped in the Western margin of Sichuan Basin. Based on the recent geological investigation，we discovered well preserved fossil woods with clear growth rings, which indicated that warm climate developed during the Xujiahe Formation deposited. The growth rings of fossil wood showed seasonal fluctuations. It was thought that the climate alternation was closely related to the megamonsoon which was prevalent from the Permian to the Triassic. Average sensitivity of the tree rings of fossil woods was calculated to less than 0.3,which showed the balanced water supply. The plant growth was strongly influenced by the magamonsoon developing during the Late Triassic.