白云凹陷浅成岩浆侵入体发育特征、成因及油气地质意义  

Characteristics and Mechanisms of Shallow Igneous Intrusions and Their Implications on Hydrocarbon Geology in the Baiyun Sag

作　　者：望畅 孙启良 解习农[1] 宋慧兰 Wang Chang;Sun Qiliang;Xie Xinong;Song Huilan(Hubei Key Laboratory of Marine Geological Resources,China University of Geosciences,Wuhan 430074,China;Department of Earth Sciences,University of Oxford,Oxford OX13AN;Exploration and Development Research Institute of Huabei Oilfield,CNPC,Renqiu 062552,China)

机构地区：[1]中国地质大学海洋地质资源湖北省重点实验室,湖北武汉430074 [2]Department of Earth Sciences University of Oxford,Oxford OX13AN [3]中国石油华北油田分公司勘探开发研究院,河北任丘062550

出　　处：《地球科学》2022年第2期505-517,共13页Earth Science

基　　金：国家自然科学基金项目(No.41676051)。

摘　　要：珠江口盆地白云凹陷内发育大量早中新世(约15.5 Ma)浅成岩浆侵入体(侵入深度<3 km).目前对其形态特征、相互关系以及岩浆侵入诱发的强制褶皱等尚缺乏系统研究.通过利用高精度三维地震资料,细致刻画了侵入体的形态、岩浆运移通道以及岩床复合体内各岩床的空间关系,定量分析了强制褶皱与侵入体的几何关系.白云凹陷内岩浆侵入体形态多样,主要包括碟状、板状、舌状、透镜状等.岩床复合体内各岩床的形态和空间相对位置可以判断岩浆来源和流动方向.岩浆侵入体主要通过临近岩床侧向供给或下部岩墙垂向供给这两种方式侵入至目前所在层位.侵入体形态主要受控于岩浆的粘度、围岩内聚力以及侵位深度3个方面.塑性变形使褶皱幅度通常小于侵入体的厚度,强制褶皱可以形成圈闭,圈闭的规模主要由下伏侵入体的范围和厚度决定.侵入体上方由差异压实产生的断层为油气运输提供了有利通道.A large number of Early Miocene(ca.15.5 Ma)shallow igneous intrusions(intrusion depths<3000 m)have been identified in the Baiyun Sag of Pearl River Mouth Basin.Their morphological characteristics,relationships and forced folds above them have not been systematically studied.This paper detailedly describes the shapes,vertical migration pathways and spatial relationships(sill complexes)of igneous intrusions,using high-resolution 3 D seismic data.Moreover,the geomorphological relationship between the forced folds and the intrusions are quantitatively analyzed.The igneous intrusions are characterized by saucer,strata-concordant,tongue orlentoid shapes.The source and flow direction of magma could be indicated from the geomorphological characteristics and spatial relationship of sills.Magma emplacement is transported from adjacent sills(lateral supply)or from dykes(vertical supply).The geomorphological characteristics of igneous intrusion are mainly controlled by the viscosity of magma,the cohesion of host rock and the emplacement depth of magma.Moreover,some igneous intrusions could trigger sediment deformations of overlying strata and form forced folds.The amplitudes of forced folds are usually less than the thickness of the igneous intrusion,because of the plastic deformation.These folds could serve as hydrocarbon traps whose sizes are mainly influenced by the scale and thickness of underlying igneous intrusion.Furthermore,normal faults that are located within the folded strata and generated by differential compaction provide pathways for vertical hydrocarbon migration.

关 键 词：岩浆侵入体 岩浆供给关系 岩床 强制褶皱 白云凹陷 油气地质 

分 类 号：P67[天文地球—海洋地质]