辽南地区晚第三纪红色风化壳及更新世高海面问题探讨

以辽南地区石槽剖面与城山头剖面的红色风化壳为研究对象,利用X射线荧光光谱仪,对风化壳剖面样品进行分析。结果表明：剖面中各采样点样品的主要化学元素含量自剖面底部到顶部无规律性变化,显示了主要化学元素在风化过程中的地球化学行为较为一致,符合风化壳沉积类型特征;剖面的主要化学成分为SiO₂、Al₂O₃、Fe₂O₃,结合各采样点样品的主要化学元素含量及SiO₂/Al₂O₃及SiO₂/R₂O₃系数,可以认为这套红色风化壳应是在高温高湿的环境条件下风化作用的产物。通过与山东庙岛群岛风化壳的对比及风化壳厚度的计算,可以认为该套风化壳的形成时代应在上新世或更早。依据风化壳在滨海地区的残存高度可以推断,自第三纪晚期以来辽南地区最高海平面高度未超过今天的海平面高度。

Neogene Red Weathering Crusts in the Southern Liaoning Province and the Discussion of High Sea Level in Pleistocene

The red weathering crust of Shicao profile and Chengshantou profile in the southern of Liaoning Province is studied by studying variation characteristics of elements, geochemical index, in order to reveal its geochemical characteristics. Based on analyzed the Neogene red weathering crusts in the southern Liaoning, the climatic and sea level changes were discussed. All the samples of the red weathering crust were analyzed for major geochemical elements by X-ray Fluorescence Spectrometry. The concentrations of major geochemical elements of the red weathering crust profile shows irregular change from the bottom to the top. By geochemical analyses, the profile has the characteristics of sedimentation type. SiO₂、Al₂O₃ and Fe₂O₃ are the three main parts in the red weathering crusts. The content of SiO₂ ranged from 49.41%-60.02%, mean average is 54.44%. The content of Al₂O₃ profile ranged from 18.61%-26.48%, mean average is 22.57%. The content of Fe₂O₃ in profile ranged from 5.92%-10.79%, mean average is 8.30%. The ratios of SiO₂/Al₂O₃ ranged from 3.19%-4.99%, mean average is 4.15%. The ratios of SiO₂/R₂O₃ ranged from 2.53%-4.21%, mean average is 3.37%. Based on analyzed SiO₂/Al₂O₃, SiO₂/R₂O₃ and the concentrations of major geochemical elements, the red weathering crusts were developed under high temperature and high humidity condition. Calculation the thickness of weathering crust and compare with the weathering crust of Shandong MiaoDao, it is believed that the formation time of this weathering crust should be Pliocene or earlier. According to the remaining height of the weathered crust of Chengshantou profile in the coastal area, the sea level today is close to the highest sea level of the southern of Liaoning province since late neogene. The remaining height of the weathered crust of Chengshantou profile in the coastal area can be used as the symbol of the highest sea level of the southern of Liaoning Province since the formation of the red weathering crust.