松辽盆地营城组火山物质分散-堆积及古火山机构重建

Regrettably, people have been unable to enter the crater in the process of volcanic edifice research. The crater section of Yingcheng formation outcropped in Jiutai area of Songliao basin has been cut into two parts. The cutted section provides the potential to solve the above problem. On the basis of field geological investigation and petrographic study in the volcanic edifice in Yingcheng formation, the volcanic strata was subdivided into volcanic cycle, volcanic period, stratigraphic unit group and stratigraphic units. To build volcanic rock composition longitudinal changes sequence and make the lateral correlation, in this study we present the whole rock geochemistry of lava, and carry forward the research of pyroclastic deposits accumulation and lava emplacein in crater. Combine high precision chronology analysis results and summarize the spatial and temporal distribution of volcanic materials in the volcanic vent. Restore the crater evolution process and reconstruct palaevolcano edifice evolution model. The significance of this project is that the using of palaevolcano edifice model in volcano geological bodies recognition would improve the precision of volcanic rocks reservoir prediction.

火山机构的研究一直有着无法进入火山口内部的遗憾，松辽盆地九台地区出露的营城组火山机构大剖面为走进火山口，重建火山机构提供了可能。本项目在对营城组火山机构内部进行野外调研和岩相学研究基础上，划分火山地层单元、单元组与火山旋回、期次；结合详细的全岩地球化学分析，开展火山口火山碎屑堆积与熔岩流的侵位作用及相模式研究，建立松辽盆地九台地区营城组火山岩组分纵向变化序列及其横向对比；结合高精度年代学分析结果，总结火山口内火山物质的时空分布规律，恢复火山口演化过程，重建古火山机构演化模式；并将此模式应用于火山地质体的地震识别，提高火山岩储层预测的精度。

本项目在对九台地区营城组火山机构内部进行野外调研和岩相学研究基础上，划分火山地层单元、单元组与火山旋回、期次；结合详细的全岩地球化学、岩石中火山玻璃的原位微区组成分析，开展火山口火山碎屑堆积与熔岩流的侵位作用及相模式研究，结合高精度年代学分析结果，得到以下认识：1）修正了松辽盆地营城组火山旋回时限值，建立了松辽盆地营城组火山地层的年代学；2）划分了火山岩地层，识别了火山口岩相，建立了火山口相堆积模式；3）划分了火山岩地层，识别了火山斜坡岩相，建立了火山口相堆积模式；4）恢复了九台地区营城组一段火山机构，建立了火山机构发育模式。此模式可应用于火山地质体的地震识别，提高火山岩储层预测的精度。