摘要
对龙江地区龙江组建组剖面进行了岩石地层、生物地层、同位素年代和岩石地球化学等多方面的研究,重新厘定了龙江组的含义.新义龙江组岩石组合由安山岩、英安岩及其火山碎屑岩、流纹质火山碎屑岩和沉积碎屑岩组成;生物化石属于EosestheriaLycoptera-Ephemeropsis trisetalis热河生物群中期生物化石组合,其中叶肢介化石以Eosestheria opima-E.（Dongbeiestheria）guanghuaensis（丰满东方叶肢介-光华东北东方叶肢介）组合为代表;火山岩的岩石地球化学SiO2含量在59.71%-75.65%之间,具有高Al2O3（12.19%-19.39%）和高Na2O（1.04%-5.24%）,较富碱性（Na2O＋K2O 3.65%-6.25%）的特点,火山岩属于高钾钙碱性岩系列;轻稀土（LREE）富集.全岩激光^40Ar/^39Ar同位素年龄等时线年龄值为125.4±1.8Ma.
On the basis of field survey, the stratotype section of Longjiang Formation is researched particularly on the lithostratigraphy, biostratigraphy, isotope chronology and lithogeochemistry. The meaning of Longjiang Formation is redefined. The neologism of Longjiang Formation consists of andesite and dacite with its pyroclastic rocks, rhyolitic pyroclastic rocks and sedimentary clastic rocks. The paleontological fossils belong to Eosestheria-Lycoptera-Ephemeropsis trisetalis fossil assemblage of the Middle Jehol Biota. Among them, Conchostracans are represented by the Eosestheria opima-E.（Dongbeiestheria）guanghuaensis assemblage. The volcanic lithogeochemistry is characterized by SiO2contents between 63.88% and 75.65%, high Al2O3（12.19% to 19.39%）, high Na2O（1.04% to 5.24%）, rich alkalis（Na2O＋K2O3.65% to 6.25%）and strong enrichment in light rare earth elements（LREE）. The isotopic age of ^40Ar/^39Ar is 125.4±1.8 Ma.
出处
《地质与资源》
CAS
2014年第3期215-221,234,共8页
Geology and Resources
基金
中国地质调查局"松辽外围中新生代盆地群油气地质综合调查"项目(编号1212010782001)资助
