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湘东北中生代发育以辉绿岩类和煌斑岩类为代表的基性岩脉,属陆内拉斑玄武岩系,部分煌斑岩属于碱性系列。岩石富集LREE,δEu负异常不明显,其形成主要受软流圈地幔部分熔融作用制约。煌斑岩类微量元素总体上具有洋岛玄武岩(OIB)岩浆源区特征,富集Nd、P、Cs而K、Rb、Sr、U、Th等富集程度不明显,Ta、Nb略有富集。辉绿岩类表现出Ta、Nb、Ti亏损,但LILE并不富集,反映地壳混染程度的增强。基性岩脉形成于陆内拉张带的构造环境,岩浆活动未受到中生代大洋板块俯冲的影响。基性岩脉在时、空及物质组成上与湘东南玄武质岩石基本一致,属于整个湘东南岩石圈拉张-减薄带的一部分。
The Mesozoic dikes represented by diabase and lamprophyre are of Mesozoic development in Mesozoic in northeastern Hunan. They belong to continental basalt strata and part of lamprophyre belong to alkaline series. The rock is enriched in LREE and the δEu negative anomaly is insignificant. Its formation is mainly controlled by the partial melting of asthenospheric mantle. The lamprophyre trace elements generally have the features of magmatic source of oceanic basalts (OIB), enrichment of Nd, P, Cs and the concentration of K, Rb, Sr, U, Th and other enrichment is not obvious, Ta, Nb slightly rich set. The diabase types show Ta, Nb and Ti losses, but LILE is not enriched, reflecting the enhancement of crustal contamination. The basic dykes are formed in the tectonic environment of the intracontinental tensile zone, and the magmatism is not affected by the subduction of the Mesozoic oceanic plate. The basic dikes are basically the same as the basaltic rocks in southeastern Hunan in terms of time, space and material composition, and are part of the tension-thinning belt in the southeastern part of Hunan Province.