Petrology, geochemistry and petrogenesis of the metabasalts of the Hutuo Group, Wutai Mountains, Shanxi, China.

Based on the field work, this paper focuses on petrology and geochemistry of the metabasalts from Sijizhuang, Qingshicun and Hebiancun formations in Hutuo group. The results show that the basalts are rich in TiO2、TFeO, and poor in MgO, suggesting the features of evolved basic magma. With high concentration of total REE contents, the LREE is moderately enriched, but the Eu anomaly is weak (or slight). The contents of Cr、Ni in the basalts change greatly and are positively corrrelated with Mg#. In spidergrams to normalized in NMORB, the basalts in Hutuo group are different from IAB in strongly negative Sr anomaly, Nb, Ta and Ti anomaly in some samples, but the Zr、Hf anomaly is absent. In addition, Nb and Ta in the basalts are not differentiated. The Zr/Hf ratio is higher than that of the MORB, being consistent with that of the intraplate basalt. The basalts of the Hutuo group might erupt in rift environment. In the ascending process of the basic magma, the fractional crystallization of olivine and spinel occurred and the basalts suffered the assimilation of crust materials to varying degree.