陕西秦岭元古宇松树沟岩组变质火山岩的地球化学特征及地质意义

中新元古界松树沟岩组出露于周至黑河黄草坡南及榨水丰河街北等地,为一套呈残块分布的含气孔、杏仁,局部具枕状构造,角闪岩相变质的中基性火山岩系夹少量碎屑岩。通过对该岩组的分析,其与洋中脊岩石化学特征较为相似,曲线较为平坦,轻稀土元素相对富集、重稀土元素相对亏损。微量元素蛛网图显示高场强元素及大离子亲石元素富集的特征。从构造环境进行分析,松树沟岩组形成于洋中脊环境。

Geochemical characteristics and tectonic significance of Proterozoic Songshugou Formation volcanic rock in Qinling Mountain, Shaanxi Province

The middle-upper Proterozoic Songshugou Formation is exposed in the south of Zhouzhiheihe Huangcaopo and the north of Zhashuifeng Street. It consists of basic igneous rocks with vesicular structure, amygdaloidal structure and local pillow structure, together with small amounts of clastic rocks. The basic igneous rocks experienced amphibolite facies metamorphism. An analysis of the Sognshugou Formation shows that, it is similar to the mid ocean ridge in petrochemical characteristics. The curve is flat, and there exists the enrichment of LREE relative to HREE. The trace element spider diagram shows it is rich in high field elements and large ion lithophile elements. An analysis of the structural environment shows that it is characteristic of the mid ocean ridge.