【摘要】 生物礁生长对水体环境参数要求苛刻,因而生物礁体系垂向演化藴藏了丰富的古海平面、古环境变化信息。基于海平面变化的层序格架内,生物礁体中元素地球化学指标呈现出较好的规律性分布。利用Panalytical衍射仪和Itrax岩心扫描仪分别对西科1井第四系生物礁滩体进行了矿物组分和元素地球化学分析,其中矿物组分结果显示不稳定的文石、高镁方解石主要分布在第四系浅层,而深层以低镁方解石为主。根据矿物组分,将第四系划分为2段:富文石段和富方解石段,分别选用不同元素指标采用频谱分析和小波变换,有效地进行了五级层序、六级层序划分,其中富文石段可进一步划分出6个五级层序和24个六级层序,富方解石段划分出21个五级层序和74个六级层序,划分结果显示,高频单元内元素指标亦呈现出规律性变化,反映了周期性的环境变化。更多还原

【Abstract】 Reef growth requires strict water conditions,and thus,the vertical evolution of the reef-bank system contains abundant information about paleo-sealevel and paleo-environment changes.Under the sequence stratigraphic frameworks based on sea level changes,geochemical indexes in the reef body may present regular distribution.The Panalytical diffractometer and Itrax Corescanner element scanner are utilized to analyze the mineral and geochemistry compositions of the Quaternary reef-bank system,respectively.Mineral composition results show that aragonites and high-Mg calcites are mainly distributed in shallow layers of the Quaternary strata,while low-Mg calcites are dominant in deep layers.Based on mineral compositions,the Quaternary strata can be divided into two sections:the aragonite-rich section and the calciterich section.Different element indexes are selected to carry out spectral analysis and wavelet transformation.This helps identify the fifth-order and sixth-order sequences effectively.The aragonite-rich section can be further sub-divided into 6fifth-order sequences and 24six-order sequences,while the calcite-rich section can be further sub-divided into 21fifth-order sequences and 74sixth-order sequences.Geochemical indexes in subdivision results also display regular distribution,suggesting the periodic environmental changes.更多还原