成都平原4 kaBP以来黏土矿物记录的古气候变化

CLAY MINERALS INDICATORS OF PALEOCLIMATE CHANGES OF CHENGDU PLAIN SINCE 4 kaBP

摘要: 利用X射线衍射方法对成都金沙遗址IT6814探坑约4 m厚(约4 kaBP以来沉积)地层剖面的黏土矿物进行了分析,发现黏土矿物主要由伊利石、绿泥石、伊利石-蒙脱石混层矿物和少量高岭石组成。根据黏土矿物含量变化的分析和对比研究,划分出成都平原黏土矿物变化的5个阶段,得出成都平原的气候变化经历了由温凉偏干与温暖潮湿的交替,在2 500 aBP发生了较为明显的快速降温过程。通过对比探讨了古人类活动对黏土矿物的影响尺度,认为古人类活动的影响较低,黏土矿物的成分和含量可以作为气候变化的指示剂。

Abstract: By the analyses of the X-ray diffraction, contents of clay minerals of the sediments from Jinsha site IT6814 of Chengdu are measured. The results show that the main types of the clay minerals are illite, chlorite, illite-montmorillonite and kaolinite. Analyses and study on these clay mineral types and contents show that Chengdu plain can be divided into five phases. Climate in Chengdu plain went from temperate-cool and a little dry to warm and moist. The temperature decreased abruptly since 2 500 aBP.And the influence of the ancient activity on the clay mineral is low. So the ingredient and content of clay mineral may be taken as the climatic indicator.