苏北平原周庄镇浅钻沉积物粘土矿物分布特征及其环境意义

Environmental Significance and Clay Mineral Characteristics of YZ1 Core Sediments in Zhouzhuang,Northern Jiangsu Plain

利用X衍射法分析了苏北平原浅钻剖面（YZ1）的粘土矿物类型和含量,并对其环境意义进行了探讨。结果表明,YZ1浅钻沉积物粘土成分主要由4种粘土矿物（伊利石、高岭石、绿泥石、蒙脱石）和少量长石、石英碎屑组成;研究区的古气候环境演变主要经历3个阶段,13 770~11 600 cal a B.P.期间的低温冷干阶段;11 600~9 610cal a B.P.期间的逐步升温阶段;9 610~1 520 cal a B.P.期间的全新世暖湿阶段,在这3个大的阶段背景条件下也存在一些次级波动。

The clay mineral was widely distributed in the quaternary sediments.The present research shows that the clay mineral was a product which effects by the diagenesis and sedimentation,under the certain climatic and sediment source condition.And it was a good substitution index for reconstructing the change of palaeoenvironment.This paper chosed the lacustrine sediment as study object which was near the subsidence center of Subei plain.Based on X-ray diffraction（XRD） analysis,the clay mineral components and their assemblage feature of one core sediments（YZ1）in Subei plain were measured.The characteristics and environmentical significance of clay minerals were analyzed.The results show that the main clay minerals in YZ1 core sediments were illite,kaolinite,chlorite and smectite,and feldspar and quartz piece were minor.The palaeoclimate of the study area has experienced three stages： 13 770-11 600 cal a B.P.,relative cold-dry period in climate.During the period,kaolinite content was with relatively low value,illite,smectite content and crystallinity were relatively high,indicating a cold-dry palaeoclimate.11 600-9 610 cal a B.P.,it grew warmer and went intowarm-moisture period.Kaolinite content increased observably,and smectite and illite decreased,suggesting atemperature and humidity gradually increase palaeoclimate.9 610-1 520 cal a B.P.,relative warm-moisture period.Kaolinite content was with relatively high value,while illite and smectite content were relatively low.Crystallinity also showed relatively low,suggesting a relatively warm and humid palaeoclimate.In addition,theclay mineral indexes also recorded several sub cold-warm changes under the background of three main period.