松辽盆地东缘下白垩统营城组二段火山碎屑沉积的过程、相和结构  

Processes,Facies and Architecture of the Early Cretaceous Pyroclastic Deposits of the Second Member,Yingcheng Formation,the Eastern Margin of the Songliao Basin

作　　者：程日辉[1] 刘万洙[1] 王璞珺[1] 侯景涛[1] 姜雪[1] 李飞[1] 

机构地区：[1]吉林大学地球科学学院,长春130061

出　　处：《吉林大学学报（地球科学版）》2007年第6期1166-1175,共10页Journal of Jilin University：Earth Science Edition

基　　金：国家"973"项目(2006CB701403)

摘　　要：松辽盆地东缘六台地区营城组露头地质调查和实验室分析显示,貌似正常碎屑岩的营二段是一套复杂的火山熔岩和沉积岩之间的过渡岩性。这套岩性包括了碎屑熔岩、凝灰岩、沉凝灰岩、凝灰质碎屑岩和正常碎屑岩,显示了它们形成于火山—沉积盆地的过渡环境,即火山斜坡过渡到冲积平原和湖泊环境。与火山作用有关岩相有4种端元的火山碎屑岩相:弹射坠落爆发空落相、喷射降落爆发空落相、热碎屑流相和热基浪相。火山物质堆积在火山斜坡以及前方的冲积平原上,往往以火山碎屑岩相或者冲积扇相、辫状河相保存;它们堆积在湖泊中则为三角洲相、扇三角洲相、较深水相和沼泽相。这些相的空间组合反映了火山喷发—碎屑堆积的过程。根据旋回发育营二段可以区分出3种类型的充填序列:沉积—火山充填序列、沉积充填序列和火山充填序列。较为完整的序列为粗碎屑岩—火山岩和火山碎屑岩—细碎屑岩,对应着裂谷类盆地断裂作用—火山作用—沉积充填的过程,记录在特定的地层结构中。Recent geological survey on the outcrops of the Yingcheng Formation exposed in the Liutai area at the eastern margin of the Songliao Basin and related laboratory analysis reveal that a set of seemingly normal clastic sedimentary rocks in the second member of the Yingcheng Formation is in fact a set of transitional rocks between lava and normal sedimentary rocks. This succession of rocks contain clastic lava, tuff, tuffite, tuff clastic rock and normal clastic rock, which suggest they were formed in a transitional environment of volcanic slope to fluvial plain or lake. There are 4 end members of volcanic clasts, including catapult airfall, ejection airfall, base surge and volcanic clasts flow. If the volcanic clasts were deposited on volcanic slope and/or fluvial plain, they would occur in the 4 faceis mentioned above or in alluvial fan and braid stream. If the volcanic clasts were deposited in lake, they would occur in delta, fandelta, shallow-deep lake, and swamp. The architecture of facies could present the forming process of volcanic eruption-clastic accumulation. The characteristics of sedimentary cycles of the second member of the Yingcheng Formation show that there are 3 kinds of basin fillings, sedimentary - valcanic, sedimentary and volcanic. The entire succession should be from coarse clastic rocks to volcanic rocks and volcanic clastic rocks and to fine clastic rocks, corresponding to rifting, volcanic activities and sedimentation in rift basin respectively.

关 键 词：松辽盆地 营城组二段 火山碎屑 沉积相 结构 

分 类 号：P618.13[天文地球—矿床学]