安徽栏杆地区橄榄辉长岩地球化学特征及其与金刚石成矿的关系

安徽栏杆地区碱性基性岩岩性为橄榄辉长岩,微量元素特征表现为大离子亲石元素(K、Rb、Sr、Th和Ba)富集,但高场强元素(Nb、Ta、Zr和Hf)无明显亏损,表明岩石形成于大陆板内环境,为地幔低度部分熔融的产物;稀土元素特征表现为LREE强烈富集,而HREE相对亏损,暗示了源区富集特征,Eu负异常显示岩浆经历了明显的斜长石结晶分异。结合中国东部碱性基性岩的金刚石成因条件及地球化学特征分析,认为本区碱性基性岩具有金刚石成矿地质条件。

Geochemical features of the olivine-gabbros and their relationship with diamond-mineralization in the Langan area,Anhui province

Langan olivine-gabbros in Anhui province belong to alkaline-basic rocks. Their major ele- ments and trace elements indicate that the rocks formed in a intraplate setting, with the characteristics of enrichment in LILE （ K, Rb, St, Th, Ba, etc. ） , and depletion in HFSE （Nb, Ta, Zr and Hf ） . The rocks are also strong enriched in LREE and relatively depleted in HREE. The REE features demonstrate the rocks coming from the deep mantle （ garnet peridotite mantle） and undergoing, before their emplace- ment , a low-degree partial melting of pyrolite. The Eu negative anomaly is obvious, showing that plagio- clases involved a fractional crystallization. According to the environment of diamond-mineralization and ge- ochemical features of alkaline-basic rocks in eastern China, it is considered that the alkaline-basic rocks in Langan area ,Anhui Province, possess favourable geological conditions for diamond-mineralization.