燕山造山带中生代火山喷发及岩浆演化

Volcanic Eruption and Magma Evolution in the Yanshanian Orogenic Belt in the Mesozoic Era

燕山造山带是中国东部中生代火山活动最强烈的地区之一,火山喷发主要有早侏罗世南大岭阶段、晚侏罗世髫髻山阶段、早白垩世东岭台阶段和东狼沟阶段。多阶段火山喷发可分为早侏罗世近EW向喷发带、晚侏罗世NE向喷发带和早白垩世NNE向喷发带。火山—沉积盆地主要有早侏罗世继承性坳陷盆地、晚侏罗世继承性断陷盆地、早白垩世新生性上叠式断陷盆地。火山喷发主要有南大岭阶段夏威夷型喷发、髫髻山阶段斯特朗博利型喷发、东岭台阶段普林尼型喷发3种类型。岩浆成分变化规律为:早侏罗世南大岭阶段以基性岩浆为主,晚侏罗世髫髻山阶段中性岩浆规模大,早白垩世东岭台阶段酸性岩浆活动强烈。

In the Yanshanian orogenic belt, volcanic eruptions were most strong and frequent in the Mesozoic. According to the tectono-magmatic cycles, the eruptions can be divided into four stages:the Early Jurassic Nandaling, the Late Jurassic Tiaojishan, the Early Cretaceous Donglingtai and Donglanggou stages. The distribution of volcanic rocks shows that the Early Jurassic eruption belts are nearly EW, the late Jurassic belts are NE, and the Early Cretaceous belts are NNE. The volcanic-sedimentary basins have different characters; the Early Jurassic basins are inherited down-warped basins, the late Jurassic ones are inherited fault basins, and the Early Cretaceous ones are neogenic stacked fault basins. There are three volcanic eruption types: the Nandaling eruption belongs to the Hawaiian type, the Tiaojishan eruption belongs to the Strombolian type; the Donglingtai eruption belongs to the Plinian type. From the Early Jurassic to the Early Cretaceous, the compositions of magma changed from the basic, intermediate to the acidic magma.