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“火山—构造洼地”指受火山作用与区域构造作用双重控制而形成的一种大型负向火山构造。区域构造作用集中体现在:断裂构造为岩浆上升和早期火山喷发提供了通道,在火山-构造洼地内形成与区域构造线方向一致的,由不同数目火山机构组成的裂隙-中心式火山喷发带;断块沉陷基本上限定了火山喷发物的堆积范围,使洼地边界显示一定线性几何形态特征。洼地底部,通常有沉陷初期形成的内陆湖盆相沉积;其上火山岩广覆,它们可以是同一旋回产物,也可是多旋回产物迭加。
“Volcano-tectonic depression” refers to a large-scale negative volcano structure formed by dual control of volcanism and regional tectonics. The regional tectonism is concentrated in the following aspects: the fault structure provides a channel for the magma to rise and the early volcanic eruption, and the fissure-center volcanic eruption belt formed by volcanic bodies of different numbers in the volcano-tectonic depressions is formed in the same direction as the regional tectonic line; Fault block subsidence basically limits the accumulation of volcanic eruptions, so that the depression boundary shows a certain linear geometric characteristics. At the bottom of the depression, there are usually inland lacustrine facies sediments formed at the initial stage of subsidence. The volcanic rocks are widely covered, and they can be the same cycle product or multiple cycle products.