中文摘要：

辽宁营口后仙峪硼矿区的超镁橄榄岩是该区硼镁石型硼矿的主要赋存岩石，其地质地球化学特征是：①超镁橄榄岩呈带状、透镜体状分布．它整合于古元古代的火山一沉积岩系中的含硼岩系富镁硼酸盐岩组中。岩石几乎由镁橄榄石组成．具有变余的火山沉积的组构。②主量元素说明岩石化学成分具富镁、富铁的特点。③非活动性微量元素较高，如Zr．Hf．Ta等，与一般超基性岩相似；Cr．Ni含量低，显示岩浆为非原始岩浆；Nb^＊大于1以及（La/Yb）N-（Yb）N图解均说明岩石的幔源性。④稀土元素总量为7.41×10^--46．82×10^-6，与上地幔相当。轻、重稀土分馏不太明显，负Eu异常明显。具有与纯橄榄岩一致的“V”型稀土元素分布模式。⑤εNd为-7.51961-9.0654，亦反映出壳幔混染的特点。由地质地球化学特征可以推测岩石为经过地壳混染的地幔橄榄岩较大程度部分熔融后而残留的富镁岩石．

英文摘要：

Super-magnesium peridotite is the main host rock of boromagnesite ore in the Houxinyu boron deposit, Yingkou, Liaoning Province. The geological and geochemical characteristics of the rock are as follows： （1） The rock occurs as concordant belts and lenses in magnesium-rich borate rocks of a boron-bearing rock sequence of the Paleoproterozoic volcano-sedimentary a blastic exhalative-sedimentary fabric. （2） rock series, and is almost all made up of forsterite and has The major elements indicate that the rock is rich in magnesium and iron. （3） Inactive trace elements such as Zr, Hf and Ta are rich, which is similar to the case of typical ultramafic rocks; the lower contents of Cr and Ni suggest a non-primitive magma, and Nb^＊〉 1 and the （La/Yb） N-（Yb） N diagram both indicate a mantle origin for the rock. （4） The total REE content ranges from 7.41 ×10^-6 to 46.82×10^-6, being similar to that of the upper mantle; the fractionation of LREE and HREE is not pronounced, with a pronounced negative Eu anomaly; and the chondrite-normalized REE patterns of the rock are ＂v＂- shaped, being similar to those of dunite. （5） The values of εNd range from -7.51961 to 9.0654, which indicates the feature of mixing of the mantle and crust. From the above-mentioned geological and geochemical characteristics, it may be inferred that the rock is magnesium-rich rock left after relatively high degrees of partial melting of mande peridotite contaminated by the crust.