黑龙江省东部晚三叠世-中侏罗世硅质岩地球化学特征及形成环境

孙雷; 曾振; 崔维龙; 王晓杰; 赵青年; 郝振群; 李寒; 张宏泽; 周江

doi:10.13686/j.cnki.dzyzy.2021.06.001

黑龙江省东部晚三叠世-中侏罗世硅质岩地球化学特征及形成环境

GEOCHEMISTRY AND FORMATION ENVIRONMENT OF THE LATE TRIASSIC-MIDDLE JURASSIC SILICEOUS ROCKS IN EASTERN HEILONGJIANG PROVINCE

摘要

摘要: 黑龙江省东部那丹哈达增生杂岩主要由晚三叠世-中侏罗世含放射虫硅质岩组成，并夹有镁铁-超镁铁质杂岩和晚古生代浅海沉积岩.对黑龙江省东部石场、勤得利和胜利农场地区硅质岩分析显示，样品Al₂O₃、TiO₂、CaO、Al₂O₃/（Al₂O₃+TFe₂O₃）及ΣREE整体上偏低，具有较高的SiO₂含量，为纯硅质岩.结合Al-Fe-Mn三角图和K₂O/Na₂O值，表明该地区硅质岩的形成过程与海底热液作用无关.元素判别图解及地球化学特征揭示，黑龙江东部三个地区的硅质岩形成于大陆坡及边缘海环境.

Abstract: The Nadanhada accretionary complex in eastern Heilongjiang Province is mainly composed of the Late Triassic-Middle Jurassic radiolarian siliceous rocks intercalated with the mafic-ultramafic complex and Late Paleozoic shallow sea sedimentary rocks. The analysis results of siliceous rocks from Shichang, Qindeli and Shengli Farm areas in eastern Heilongjiang Province show that the samples, characterized by generally low Al₂O₃, TiO₂, CaO and ΣREE contents and low Al₂O₃/(Al₂O₃+TFe₂O₃) ratio and high SiO₂ content, are pure siliceous rocks. Combined with the Al-Fe-Mn triangle diagram and K₂O/Na₂O ratio, it is indicated that the formation of siliceous rocks has nothing to do with seafloor hydrothermal process. The element discrimination diagram and geochemical characteristics reveal the siliceous rocks in the above three areas were formed in continental slope and marginal sea environment.

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