摘要： 火山活动或热液活动提供的深源物质可以保存在沉积岩中。在滦平盆地西瓜园组下段存在以玄武岩、泥晶碳酸盐岩纹层为代表的深源物质,可用通过薄片观察和地球化学分析手段,针对深源物质对其环境及油气成藏的影响进行分析。结果表明,西瓜园组下段的深源物质主要是通过水下火山喷发和热液喷流活动进入沉积岩中的。通过环境指标(Th/U、V/Cr、V/(V+Ni)、CIW、Sr/Cu等)的变化规律,发现热液喷流活动对环境是频繁、剧烈的短暂影响,而水下火山喷发对环境是间或、较弱的长期影响。通过富有机质层与热液强度指标((Fe+Mn)/Ti、Al/(Al+Fe+Mn))的对比发现,富有机质层具有高(Fe+Mn)/Ti值、低Al/(Al+Fe+Mn)值的特点。根据以上研究表明,深源物质的参与极大地提高了古生产力,其喷发、喷流机制使得水体缺氧、分层,为有机质提供了良好的保存条件。

关键词: 滦平盆地, 白垩系, 深源物质, 热液喷流, 水下火山, 油气成藏

Abstract: The deep source material mainly enters the sedimentary rock through volcanic activity or hydrothermal activity. The lower member of Xiguayuan Formation in Luanping Basin is a set of fine-grained sedimentary rocks affected by deep source material,so thin section observation and geochemical analysis were carried out to study the influence of deep source material on the environment and hydrocarbon accumulation in the study area. The results show that the deep source material in the lower member of Xiguayuan Formation mainly entered the sedimentary rocks through underwater volcanic eruptions and hydrothermal jet activities. Through the variation law of environmental indicators(Th/U,V/Cr,V/(V+Ni),CIW,Sr/Cu,etc.),it is found that hydrothermal jet activities have frequent and severe short-term effects on the environment,while underwater volcanic eruptions have occasional,weak long-term effects on the environment. By comparing the organic-rich layer with the hydrothermal strength index((Fe+Mn)/Ti,Al/(Al+Fe+Mn)),it is found that the organic-rich layer has high value of (Fe+Mn)/Ti,low value of Al/(Al+Fe+Mn)characteristics. According to the above studies,the participation of deep source materials has greatly improved the ancient productivity,and its eruption and jet flow mechanism has made the water body anoxic and stratified,providing good preservation conditions for organic matter.

Key words: Luanping Basin, Cretaceous, deep source material, hydrothermal jet, underwater volcano, hydrocarbon accumulation

中图分类号: 

• P588.21