【摘要】 黑龙江省依兰地区分布的黑龙江杂岩被认为是具有缝合带性质的构造混杂岩,其中所含变基性火山熔岩中含有的变质矿物不具有定向组构特征,因此称之为块状蓝片岩。特征变质矿物——蓝闪石的大量出现表明其经历过高压低温变质作用。常量地球化学分析表明,其SiO2含量均在53%以下,TiO2含量超过2%,Na2O+K2O的含量为2.77%~6.41%,Na2O的含量普遍大于K2O的含量,Na2O+K2O-SiO2变异图显示其具有碱性玄武岩特征;痕量元素地球化学分析显示其轻重稀土元素分异明显,稀土元素配分曲线表现为轻稀土元素富集、重稀土元素亏损的右倾型。球粒陨石标准化图解中,不具有Eu的负异常;Nb×2-Zr/4-Y、Ti/100-Zr-Sr/2与Ba-Th-Nb-La图解的综合分析表明,块状蓝片岩具有碱性洋岛玄武岩(OIB)的特征,它们应是佳木斯地块与松嫩地块之间古洋壳俯冲过程的残留,这为探讨佳木斯陆块与松嫩陆块之间古老洋盆俯冲消减过程提供了重要依据。更多还原

【Abstract】 Heilongjiang mélange distributed in Yilan area of Heilongjiang Province is regarded as the tectonic mélange with features of suture zone.Some metamorphic basic lavas consisting of quite a few metamorphic minerals without directional characteristics are named massive blue schist.The existence of large quantities of glaucophane,a characteristic metamorphic mineral,indicates that these basic lavas have undergone high P low T metamorphism.Geochemical analyses of major elements show that all the samples have the following characteristics: SiO2<53%,TiO2>2%,and Na2O+K2O=2.77%～6.41%.Geochemical analyses of trace elements reveal that the fractionation between LREE and HREE is quite obvious and the distribution pattern of REE is right oblique,with no negative Eu anomaly in the chondrite-normalized diagram.The Na2O+K2O-SiO2 variation diagram indicates that metamorphic basic lavas have characteristics of alkali basalt,and the Nb×2-Zr/4-Y,Ti/100-Zr-Sr/2 and Ba-Th-Nb-La diagrams all suggest that these metamorphic basic lavas have characteristics of alkali ocean island basalt(OIB).The above understanding provides important evidence for the research on subduction of the palaeo-ocean crust between Jiamusi continental block and Songnen continental block.更多还原