摘要
中国白垩纪大陆科学钻探松科1井连续取明水组岩心长558.94m,岩心收获率为93.69%,是迄今获取的最连续完整的沉积记录。文章对此进行了厘米级(分层厚度2~5cm)沉积地质描述。明水组沉积时期与坎潘晚期至丹尼期对应。通过对松科1井明水组岩心的精细描述,揭示其岩性-岩相-旋回的沉积序列及其作用过程。明水组共识别出15种基本岩石类型,为曲流河、浅湖和滨湖亚相的河床滞留、点砂坝、天然堤、决口扇、决口水道、河漫滩、河漫湖、浅湖静水泥、临滨砂坝、风暴沉积、沙滩、泥滩、浊流、重力流水道等15种沉积微相。在岩相序列上识别出20种共361个米级旋回(六级旋回)、109个五级旋回、29个四级旋回、3个三级旋回。完整组段的厘米级刻画为高精度沉积过程研究提供了可能,明水组全井段取心对松辽盆地富氧事件、K/Pg界线、坳陷盆地晚期构造演化以及盆地浅层生、储、盖组合的研究具有重要意义,该文的精细描述资料为今后相关的深入研究提供了迄今最精准的基本地质素材。
China Cretaceous Continental Scientific Drilling(CCSD) in the Songliao Basin,called SK1 project,collected 558.94 m of Mingshui Formation which corresponded to the late Campanian to Danian.The borehole got a highly continuous core section with recovery of 93.69%,that is the most complete and precise sedimentary records up to now in the basin.Thicknesses of the description can be as thin as 2-5 cm for the interbedding sequences.We described in centimeter-scale the sedimentary sequence,lithology,lithofacies and cyclic stratigraphy at the drilling spot.Fifteen litho-types were recognized in the section.Sedimentary facies are predominantly river and lacustrine that can be subdivided into fifteen microfacies including point bar,natural levee,crevasse splay,crevasse channel,flood plain,flood lake,mudstone of still water,nearshore bar,tempestite,sandy beach,mudy beach,turbidite and gravity flow channel microfacies.The whole sequence is composed of 361 meter-scale cycles(sixth-order cycle),109 fifth-order cycles,29 fourth-order cycles and 3 third-order cycles.Centimeter scale depiction of the section revealed some previously unknown horizons,which is very important for us to interpret basin evolution features such as lake oxic events,K/Pg boundary,tectonism in late sag basin stage and the source-reservoir-cap rock assemblages in shallow stratigraphy.That is to say,the scientific drilling provides us with powerful insight into the basin.Researchers who are interested in the basin can do their reasonable analysis of the basin on the basis of the precise original materials in the paper.