白杨河杨庄地区铀矿区基性岩脉地球化学特征及其源区性质

Geochemical Characteristics and the Provenance of Basic Dikes in Yangzhuang Area of Baiyanghe Uranium Ore Deposit

白杨河铀矿区近南北向分布的辉绿岩构成区内基性岩脉的主体。研究表明,杨庄地区铀矿床辉绿岩形成于大陆板内构造环境,地壳物质的混染作用影响不明显,基本表示了原始岩浆的成分。岩石具有明显的LREE富集(La/Yb)N=3.02~5.07和大离子亲石元素(K,Ba等)富集现象,亏损高场强元素Nb和Ta;略微高Eu正异常;源区与深俯冲作用引起的地幔交代作用有关;稀土元素及微量元素比值表明,杨庄地区铀矿床辉绿岩源区为过渡型地幔源区,其成因与白杨河地区地壳物质熔融和岩浆结晶分异作用有关。

The SN-extending diabase dikes are developed in Baiyanghe uranium lot. Geochemical characteristics and the provenance of diabase form Baiyanghe area uranium deposit have been studied form the aspects of major and trace elemental geochemistry. It can be concluded that the amphibolic diabases formed at internal plate tectonic setting with less crustal rocks assimilation during their intrusion and evolution,which mostly represent the primary magma form the mantle. The rocks are obvious enriched LREE enrichment( La / Yb)N= 3. 02 ~ 5. 07 and large ion lithophile elements( K,Ba,etc.),loss of high field strength elements Nb and Ta; slightly high Eu is abnormal. Source region associated with deep mantle metasomatism which caused by subduction. The ratio of rare earth elements and trace elements suggested that diabase Yangzhuang area uranium deposit source area for transitional mantle source region,and related to crust molten and magmatic crystallization differentiation of the Baiyanghe region.