苏北东海榴辉岩地球化学及原岩成因

苏北东海榴辉岩的原岩为蛇绿岩基性熔岩和堆积镁铁岩。其玄武岩的化学成分相当于洋脊拉斑玄武岩，并富集大离子亲石元素、稀土元素和轻稀土元素，属于Ｅ型洋脊玄武岩。它们形成于扬子古大陆板块北缘苏北－胶南地体与胶北地体间洋盆环境中的局部异常脊，是由富集地幔低程度部分熔融和来自深部岩浆的分离结晶作用而形成，由于俯冲消减作用遭受相对低温高压（超高压）的榴辉岩相变质和强烈破碎，被挤压到东海群下部不同构造层位中，是外来的被肢解的蛇绿岩块。

Geochemistry of Donghai Eclogites in northern Jiangsu and Origin of Their ProtoIiths

Eclogite masses and some other rocks in Donghai-Ganyu area of JiangsuProvince show many chairactoristics of ophiolites and seem to be relict fra-gments of the oceanic crust.The protoliths must be basic lava and cumulatemafic rocks of ophiolftes,The basalt exhibits chemical composition of oceanicridge tholeiite and contains abundant large-ion lithophile elements,REE andLREE,thus belonging to E-MoRB,These rocks were formed in an ocearnicbasin environment between the Subei-Jiaonan terrane and the Jiaobei terra-ne,with their magma derived from the partial melting of the enriched ma-ntle and the deep mantle current.As a result of plate subduction and colli-sion,these plutonic eclogites were emplaced in different horizons of the Do-nghai Group.