海南岛周边海域表层沉积物中粘土矿物组合及其气候环境意义

X射线衍射分析结果显示,海南岛周边海域表层沉积物中粘土矿物主要由伊-蒙混层矿物、伊利石、高岭石和绿泥石等组成,其含量分别为34.2%,27.3%,21.1%和17.4%。采用人工判别分区和Q型聚类分析分区相结合的方法,将研究区按粘土矿物的相对含量和分布水深,划分出3个粘土矿物组合区,各分区的矿物组合特点显示它们的赋存现状受控于各种粘土矿物本身的粒度、形态特征、水动力条件和水深等因素。在南海海域首次鉴别出有较高含量的伊-蒙混层矿物存在,根据前人对伊-蒙混层矿物、伊利石和高岭石所指示气候条件的研究结果和本研究区内这些表层粘土矿物的含量、组合特征,判断海南岛及周边区域1 500 a以来一直处于比较温湿的气候环境。

THE ASSEMBLAGE AND ENVIRONMENTAL AIGNIFICANCE OF CLAY MINERALS IN THE SURFICIAL SEDIMENTS AROUND HAIMAN ISLAND

The species and contents of the clay minerals in the surficial sediments around Hainan Island are studied by X-ray diffraction analysis.The clay minerals of are mainly mixed clay minerals of illite/smectite(34.2%),illite(27.3%),kaolinite(21.1%) and chlorite(17.4%).Artificial discrimination and Q-type cluster analysis methods are used to study the assemblages and distribution trends of the clay minerals in the area.According to the quantifiable factors,the relative contents of various clay minerals and sampling depths,the shallow seafloor around the Hainan Island can be divided into three subareas with different clay mineral assemblages.The features of these assemblages were controlled by differential sorting of the clay minerals,the dynamics and depth of the sea water.For the first time in South China Sea,so much illite/smectite minerals were identified.From the research results,combined with the previous literatures,it is deduced that the Hainan island and its surround area had a worm and damp paleoclimate since 1 500 a.