济阳拗陷新生代火成岩的识别

Identification of Cenozoic igneous rocks of Jiyang depression

火成岩与沉积岩的岩石物性有明显区别,具有密度大、电阻率高、磁化率高、地震波速度高及对地震波能量 衰减强烈等特点,因此火成岩在沉积盆地内会产生明显的地球物理异常特征。研究表明,济阳拗陷是一个中、新 生代的断陷盆地,盆地内发育了古近纪早期、古近纪晚期、新近纪-第四纪等三期新生代火成岩,具有较明显的 板状、丘状、盆状、蘑菇状、杂乱状等地震反射特征,表现为显著的重力正异常和磁性异常,异常主要集中在南部 的高青和北部的无棣两大异常中心区,代表了济阳拗陷火山活动的两个中心。综合分析地震、钻井、重力、磁力 等资料后认为,济阳拗陷火成岩总体沿深断裂分布,火成岩岩性以基性岩为主,可以分为南、北两带,新生代火 成岩主要分布于东营凹陷西部和惠民凹陷东部,岩浆活动由北向南迁移。

There is significant difference in petrophysical property between the igneous rock and sedimentary rock,the former is characteristics of large density, higher resistivity and magnetic susceptibility higher velocity of seismic wave and strong attenuation of energy of seismic wave, therefore, the igneous rock can produce significant geophysical anomalous feature in sedimentary basin. The studied results showed that the Jiyang depression is Mesozoic and Cenozoic fault basin,the three epochs of Cenozoic igneous rock such as Early Paleogene,Late Paleogene and Neogene-Quaternary have been developed in the basin that have distinguished seismic reflection feature of sheetlike, dome, basin-shaped, mushroom and fuzzy and appear distinguished positive gravitational anomaly and magnetic anomaly. The anomaly manly concentrates in two central anomaly zones: Gaoqing in the south and Wudi in the north where the two centers of volcanic activity in Jiyang depression are presented. It is considered after integrative analysis of seismic,drilling,gravitational and magnetic data that the igneous rocks in Jiyang depression generally distribute along the deep faults, the igneous lithology mainly is basic rock that could be divided into two belts:the south and north belts. The Cenozoic igneous rocks mainly distribute in the west part of Dongying sag and the east part of Huimin sag, magmatic activities tends to migrate from the north to the south.