斯里兰卡普塔拉姆地区ZK593号钻孔沉积物的地球化学特征及意义

Geochemical characteristics and implication of ZK593 sediments in Puttalam,Sri Lanka

根据岩性、主微量元素特征和元素比值分析,斯里兰卡普塔拉姆地区ZK593钻孔的沉积物可分为6段。它们分别沉积于温暖潮湿、水动力较强的浅海一滨海相环境,经历了3次明显的海水进退。各层北美页岩标准化曲线平缓,轻重稀土元素没有明显的分异,Ce轻度亏损;球粒陨石标准化曲线斜率为负,轻稀土元素相对富集,各层Eu亏损明显,Ce轻度亏损,表明沉积物属于受陆源影响的陆棚沉积物。Ce负异常与碳酸盐沉积及气候环境有关。元素相关系数分析表明,Ca和Sr与生物作用关系明显;∑REE与Al_2O_3和SiO_2等微量元素与陆源碎屑关系密切。δ^(18)O的负向偏移与沉积后地下水的作用有关。

Sedimentsof ZK593 in Puttalam of Sri Lanka were divided into six parts according to lithology and the characteristics of geochemical elements. They indicate that sedimentary environment was warm and humid continental shelf with strong hydrodynamic force. Three sedimentary cycles of transgression and regression were recognized. The curve of the REEs normalization values（sample/NASA） is gentle. LREE and HREE do not separate obviously. The Ce in the each layer is lightly deficit. The curve of the REEs normalization values（ sample/ chondrite） is negative slope. The light REEs are relatively rich. The Eu in the each layer is greatly deficit, and Ce is lightly deficit, which suggests that the sediments of ZK593 have characters of shelf sediments, affected by Terrestrial detritus sediments. Negative Ce anomaly is mainly affected by climate and environment and carbonate. Correlative analysis shows that Ca and Sr have significant relationship with the biological role. ∑REE, A1203, SiO2 and trace elements probably came from the Alsilicate minerals. Negative offset of δ13C and δ18So is related to dilution effects of groundwater and early diagenesis.