识别陆相层序界面的地球化学方法

Geochemical Methods for Identification of Continental Sequence Interfaces

粘土矿物、微量元素普遍存在于各种类型的沉积物和沉积岩中,它们对环境的变化极为敏感,同时它们的沉积分异、组合特征、矿物成分及其含量都从不同的角度记录了形成过程中各种环境因素的变化。这些对恢复古环境,研究陆相湖盆水深变化具有重要的指示意义。通过对东营凹陷胜北断层下降盘沙三段—沙四上段各层序内部单元中岩石地球化学标型参数的研究发现,地层单元形成过程中,在古气候驱动下的湖平面变化旋回中,沉积岩中的矿物成分(主要指粘土矿物和胶结物)、化学成分(微量元素)等皆发生周期性变化。

Clay minerals and tr ace elements are universally distributed in various deposits and sedimentary roc ks.They are extremely sensitive to environmental changes.And the characteristi cs of their sedimentary differentiation and combination as well as mineral compo sition and con-tents have recorded the changes of various environmental factors when they formed.It is of an important indicating significance to reconstruct paleo-environment and to study continental lake basin's varied water depth.T aking each sequential element of the third member and the fourth upper member o f Shahejie formation in Sengbei fault's downthrow,Dongying sag as an example,t he lithologic geochemical typomorphic parame-ters are studied.It is suggested that in cyclic lake-level changes controlled by paleo-climate,cyclic changes could occur in mineral composition(clay minerals and cements),chemical compo sition(trace element),etc.,in sedimentary rocks.