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地质学报  2001 

中国大陆科学钻探工程预先导孔中片麻岩-花岗质片麻岩的岩石学和地球化学研究

, PP. 70-81

Keywords: 片麻岩,花岗质片麻岩,地球化学,成因机制,预先导孔CCSD-PP1,东海

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Abstract:

中国大陆科学钻探工程预先导孔(CCSD-PP1)中岩心的岩性十分复杂,主要由片麻岩-花岗质片麻岩、超基性岩、榴辉岩及少量多硅白云母石英片岩、斜长角闪岩及角闪云母片岩组成。其中片麻岩-花岗质片麻岩是最重要的岩石类型。根据片麻岩的岩相学及其地球化学特征,确定片麻岩类岩石的原岩为一套具有较高成熟度的碎屑沉积岩-低成熟度的酸性火山岩、碎屑沉积岩建造,并与在其内部里夹层形式存在的榴辉岩一起经历了超高压变质作用。花岗质片麻岩可分为三种类型:绿帘黄铁二长花岗质片麻岩、绿带黑云二长花岗质片麻岩和绿帘二云二长混合片麻岩。绿帘黄铁二长花岗质片麻岩SiO_2含量最高,为76.72%~78.86%,具有强烈的负Eu、Ba异常,Eu/Eu~*=0.125,Ba/Ba~*=0.095~0.396,其稀土和微量元素的配分模式与具有极高成熟度碎屑沉积岩部分熔融而成的花岗岩性质十分相似。该类花岗质片麻岩可能在苏鲁超高压变质带形成之前,由具有极高成熟度的碎屑沉积岩部分熔融而成的岩浆,侵入到片麻岩类的表壳岩中,并经历了超高压变质作用。绿帘黑云二长花岗质片麻岩、混合片麻岩的SiO_2含量明显偏低,且稀土、微量元素配分模式明显不同于绿帘黄铁二长花岗质片麻岩,该类岩石可能由片麻岩类岩石在超高压变质作用峰期阶段和近等温减压第一阶段深

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