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大兴安岭北部上护林盆地恩和大岭火山机构主要由白音高老组酸性熔岩、火山碎屑岩、次火山岩及火山-沉积岩组成。实测剖面显示,该火山机构由侵出相、溢流相、爆发相、次火山岩相及火山沉积相构成,不同岩性、岩相围绕火山口大致呈对称分布,产状外倾,为中心式喷发的穹状火山。溢流相的流纹岩和次火山岩相的正长斑岩锆石U-Pb测年结果分别为(115.3±2.3)Ma和(114.3±1.6)Ma,表明恩和大岭火山机构形成于早白垩世晚期。该火山机构为一次简单的火山喷发旋回一个喷发期次,大致的火山活动过程可分为四个阶段,第一阶段为早期岩浆溢流阶段,形成溢流相流纹岩夹少量流纹质角砾凝灰岩;第二阶段为晚期火山爆发阶段,产生大量的爆发相火山碎屑岩;第三阶段为岩浆侵入阶段,分别形成侵出相松脂岩、次火山岩相正长斑岩等;第四阶段为火山活动的间歇阶段,形成火山沉积相火山-沉积岩。
The Daheling volcanic unit in the upper part of the Da Hinggan Mountains is mainly composed of acid lava, pyroclastic rocks, subvolcanic rocks and volcanic-sedimentary rocks in the Baiyinogosao Formation. The measured sections show that the volcanic unit is composed of an invaded facies, an overflow phase, an eruption phase, a subvolcanic facies, and a volcanic sedimentary facies. The lithology and lithofacies distribute roughly symmetrically around the crater, Erupting dome volcano. The zircon U-Pb dating of rhyolites from the rhyolite and subvolcanic facies is (115.3 ± 2.3) Ma and (114.3 ± 1.6) Ma, respectively, indicating that the Enhe Da Ling volcano is formed in the early Late Cretaceous. The volcanic body is a simple volcanic eruption cycle an eruption period, the general volcanic activity can be divided into four stages, the first stage of the early magmatic overflow stage, the formation of overflow rhyolite clip a small amount of rhagales Gravel tuff; the second stage is late volcanic eruption stage, resulting in a large number of explosive phase pyroclastic rocks; the third stage is the magmatic intrusion stage, respectively, the formation of intrusive facies rosette, subvolcanic facies ZhengPe porphyry; the fourth stage Volcanic sedimentary facies volcano-sedimentary rocks formed during the interval of volcanic activities.