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托云盆地晚白垩世—早第三纪碱性橄榄玄武岩Sr、Nd、Pb同位素组成表明 ,本区玄武岩以低Sr、Pb和相对高的Nd同位素值 (87Sr/ 86 Sr为 0 .70 3554～ 0 .70 3884 ;14 3Nd/ 14 4 Nd为0 .512 838～ 0 .512 90 4 ;2 0 6 Pb/ 2 0 4 Pb为 18.0 0 6 3～ 18.4 72 0 ;2 0 7Pb/ 2 0 4 Pb为 15.4 4 11～ 15.50 6 0 ;2 0 8Pb/ 2 0 4 Pb为 37.80 72～ 37.92 90 )为特征 ,相似于夏威夷的洋岛玄武岩。玄武质岩石的主要元素、微量元素和稀土元素特征进一步揭示 ,本区玄武质岩石起源于交代富集型地幔。这种富集型地幔经低度熔融形成原始岩浆 ,并在上升过程中经高位岩浆房的分离结晶作用 ,最终形成玄武质岩石。
The Sr, Nd and Pb isotopic composition of the Late Cretaceous-Oligodectic basaltic olivine basalts in the Tuoyun Basin show that the basalts in this area are characterized by low Sr, Pb and relatively high Nd isotopic values (87Sr / 86 Sr 0.70 3554 ~ 0 .70 3884; 14 3Nd / 14 4 Nd is 0.512 838 ~ 0 .512 90 4; 20 6 Pb / 2 0 4 Pb is 18.0 0 6 3 ~ 18.4 72 0; 2 0 7 Pb / 2 0 4 Pb 15.4 4 11-15.50 6 0; 208 Pb 2 0 4 Pb is 37.80 72-37.92 90), similar to the oceanic island basalts in Hawaii. The main elements of the basaltic rocks, trace elements and rare earth elements further reveal that the basaltic rocks in this area originated from the enriched mantle. This enriched mantle melts to form the original magma, which is separated and crystallized by the upper magmatic chamber during the ascending process to finally form basaltic rocks.