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大兴安岭北部战备村地区出露一套火山岩,岩石组合主要为一套浅灰色、灰白色流纹质火山碎屑岩、流纹质火山熔岩、碎屑熔岩夹少量火山沉凝灰岩。在1∶5万区域地质填图的基础上,查明该套地层下部呈角度不整合覆盖于晚三叠世二长花岗岩之上,上部被中—上侏罗统塔木兰沟组平行不整合覆盖,锆石U-Pb同位素年龄为178~192Ma,时代为早侏罗世。根据《中国地层指南》关于新建“组”的要求,指定战备村剖面为层型,新建为战备村组。下侏罗统地层单位的建立,对大兴安岭早中生代火山构造岩浆活动的研究及中生代火山岩地层划分对比具有重要地质意义。
A volcanic rock is exposed in the area of Beibu village of northern Da Hinggan Mountains. The rock assemblage is mainly composed of a series of light gray, gray-flow rhyolitic pyroclastic rocks, rhyolitic volcanic lava and clastic lava with few volcanic sedimentary tuffs. Based on the 1: 50000 regional geological mapping, it is found that the lower part of this set of layers is angularly unconformable over the Late Triassic monzonitic granite, and the upper part is parallelly unconformable by the Middle-Upper Jurassic Tuamulang Formation Overlay, zircon U-Pb isotope age 178 ~ 192Ma, the era of the early Jurassic. According to the requirements of the “China Stratigraphy Guide” for the newly-built “Group”, the section of ZhanBai Village is designated as a layer type and a new battle preparation village group is newly established. The establishment of Lower Jurassic strata has important geological significance for the study of Early Mesozoic volcanic tectonic magmatism and the comparison of Mesozoic volcanic strata in the Greater Xing’an Mountains.