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长岭断陷早白垩世火山岩富硅、富碱,岩石以非碱性系列为主,包括钙碱性和高钾钙碱性系列,碱性系列火山岩为钾玄岩系列。酸性岩与中、基性岩的微量元素特征差别明显,岩石总体微量元素特征与造山带火山岩相似,富集LREE、Rb、K和大离子亲石元素,TiO2含量低,贫Sr。火山岩的形成与造山带岩石圈拆沉作用引起地壳拉张减薄的大地构造背景有关。研究区基性火山岩为地幔岩部分熔融作用的产物,岩浆演化过程中存在单斜辉石和橄榄石等矿物的分离结晶作用,中性岩为原生玄武质岩浆分异演化的产物,营城组酸性火山岩的形成与构造活动存在直接关系,为构造剪切挤压应力致使上地壳重熔的结果。
The volcanic rocks of the Early Cretaceous in the Changling fault depression were rich in silicon and rich in alkali. The rocks are mainly non-alkaline series including calc-alkaline and high-K calc-alkaline series and basic series of volcanic rocks series of potash. The characteristics of trace elements in acid rocks and basic rocks are obviously different. The overall trace elements in rocks are similar to volcanic rocks in the orogenic belt. They are enriched in LREE, Rb, K and large ion lithophile elements and have low TiO2 content and poor Sr content. The formation of volcanic rocks is related to the tectonic setting of the earth caused by the delamination of the lithosphere in the orogenic belt. The basic volcanic rocks in the study area are the products of partial melting of mantle rocks. There are the crystallization and separation of minerals such as clinopyroxene and olivine during the evolution of magmatism. The neutral rocks are the products of the differentiation and differentiation of primary basaltic magmatic magma. The acidity The formation of volcanic rocks is directly related to the tectonic activity, which is the result of remelting upper crust for the purpose of tectonic shear compression stress.