贵州地区新元古代-三叠纪沉积岩中稀土元素地球化学特征与地壳演化

REE CHARACTERISTICS IN NEOPROTEROZOIC TO TRIASSIC SEDIMENTARY ROCKS AND ITS RELATION TO CRUSTAL EVOLUTION IN GUIZHOU PROVINCE

通过对贵州地区自新元古界板溪群—三叠系深水相泥质岩系统的稀土元素地球化学研究，发现寒武系、泥盆系和上二叠统这３个稀土元素组成明显不同于其他层位和后太古代页岩稀土元素特征的异常层，并由此构成了地质历史中３个明显的稀土元素地球化学旋回。这３个稀土元素地球化学旋回与本区的大地构造旋回具有明显的一致性，且上述的３个稀土元素地球化学异常层正好与盆地发育的明显的拉张裂陷时期相对应，说明在盆地拉张裂陷时期来自盆下深部物源的加入是造成稀土元素地球化学异常的根本原因。这为我们正确认识本区的地壳演化提供了强有力的地球化学证据。

hrough the systematic study of REE geochemistry of mudstone from Neoproterozoic to Triassic in Guizhou Province, three geochemical abnormal horizons, Cambrian, Devonian and Upper Permian, in which the REE characteristics are quite different from those of the other strata, are discovered. Because of the alternate occurrence of the three geochemical abnormal horizons, three REE geochemical cycles can be distinguished, and they are corresponding to the geotectonic cycles. This point provides a strong geochemical evidence for understanding the geotectonic evolution of this area.