古黄河三角洲典型钻孔XJ01第四纪沉积物地球化学特征

Geochemical characteristics of Quaternary sediments of typical borehole XJ01 in ancient Yellow River Delta

江苏古黄河三角洲为全球海陆相互作用研究的典型地区,研究其第四纪沉积环境演化有助于进一步认识和理解海陆变迁、气候变化特征。本文基于XJ01典型钻孔第四纪沉积物的常量、微量元素地球化学,开展了沉积环境示踪。常量元素Al_(2)O_(3)、Fe_(2)O_(3)、FeO、MgO、CaO、MnO、P_(2)O_(5)、TiO_(2)总体上与SiO_(2)呈负相关关系。钻孔中地球化学元素曲线中,CIA、SiO_(2)/Al_(2)O_(3)、SiO_(2)/(Al_(2)O_(3)+Fe_(2)O_(3))、SiO_(2)/(K_(2)O+Na_(2)O+CaO+MgO)等变化趋势基本一致,微量元素Be、Rb、Cr、Cu与Rb/Sr变化趋势基本一致。地球化学元素曲线钻孔中沉积物分为10个带,分带反映该孔第四纪沉积环境由还原到氧化、水环境由深水到浅水、沉积相由陆相到海相、古气候由湿热到干冷频繁交替的特征。该研究成果为恢复古黄河三角洲地区第四纪地质演化过程提供了基础地质资料。

The ancient Yellow River Delta in Jiangsu is a typical area for the study of global land-sea interaction.The study of the evolution of the Quaternary sedimentary environment can better understand the characteristics of land-sea changes and climate change.This paper uses the geochemistry of major and trace elements in the Quaternary sediments of the typical XJ01 borehole to conduct sedimentary environment tracing research.The results show that Al_(2)O_(3),Fe_(2)O_(3),FeO,MgO,CaO,MnO,P_(2)O_(5),and TiO_(2)are negatively correlated with SiO_(2).In the geochemical element curves in the borehole,the change trends of CIA,SiO_(2)/Al_(2)O_(3),SiO_(2)(/Al_(2)O_(3)+Fe_(2)O_(3)),and SiO_(2)(/K_(2)O+Na_(2)O+CaO+MgO)are basically consistent,and the change trends of trace elements Be,Rb,Cr,and Cu are basically consistent with Rb/Sr.The geochemical element curve shows that the sediments in the borehole are divided into 10 zones,which reflect the frequent alternation of the Quaternary sedimentary environment from reduction to oxidation,the water environment from deep water to shallow water,the sedimentary phase from continental to marine,and the paleoclimate from humid and hot to dry and cold.The research results provide basic geological data for presenting the Quaternary geological evolution process in the ancient Yellow River Delta area.