郯庐断裂带鲁皖段新生代玄武岩形成机制的稀土判别

Discrimination of Mechanism of Formation of Cenozoic Basalts along Shandong-Anhui Part of Tan-Lu Fault Zone by Using Rare Earths

根据郯庐断裂带鲁皖段早第三纪、中新世以及更新世玄武岩的稀土元素特征的研究,应用稀土判据探讨了区内玄武岩的形成机制。稀土元素和常量元素的相关关系显示,郯庐断裂带新生代3个阶段玄武岩成岩过程中分离结晶作用不明显,其形成机制应该为上地幔部分熔融作用。通过多种稀土元素联合协变关系也同样反映了这些玄武岩的形成机制为上地幔部分熔融作用,同时也显示区内新生代玄武岩的稀土元素特征继承了其源区物质的稀土元素特征。这一结论与区内Sr,Nd同位素研究的结果相吻合。

Based on the characteristics of rare earth element in Paleogene, Miocene and Pleistocene basalts along Shandong-Anhui part of the Tan-Lu fault zone, the mechanism of formation of basalts was discussed. The correlativity of rare earth elements and major elements shows that the fractional crystallization is undistinguishable during the formation of the three stages of Cenozoic basalts, and the mechanism of formation of basalts should be the partial melting of the upper mantle. The study of the relationship of manifold rare earth elements also shows that the mechanism of formation of these basalts is the partial melting of the upper mantle. The results also show that the rare earth elements in Cenozoic basalts inherit the characteristics of those in its source materials. The research results coincide with Sr, Nd isotope examination. It has very important implications to discuss further sapphires deposit.