辽宁大连地区震旦系甘井子组层序地层研究

STUDY ON THE SEQUENCE STRATIGRAPHY OF SINIAN GANJINGZI FORMATION IN DALIAN REGION,LIAONING PROVINCE

大连地区甘井子组是辽宁重要的新元古界层位,发育大量的碳酸盐岩.运用经典层序地层学理论,通过对野外实测剖面的综合分析,对大连地区新元古界震旦系甘井子组进行层序地层学研究,共识别出5个层序界面,划分了4个三级层序,15个准层序组和55个准层序.甘井子组碳酸盐岩沉积可划分为局限台地亚相和开阔台地亚相,进一步划分为潟湖、潮坪、潮下低能和浅滩微相.运用区域大地构造和天文旋回方法对甘井子组环境演化进行探讨,认为其经历了局限台地→开阔台地→局限台地的演化过程.受扬子旋回末期低幅度的构造升降作用影响,大连地区南关岭期末期—甘井子期出现了5次短暂暴露,形成了5个层序界面.同时受周期性天文旋回的影响形成了准层序、层对等高频旋回.通过对大连地区甘井子组进行层序地层和沉积演化研究,为探索辽东南地区的油气资源提供依据.

The Ganjingzi Formation of Dalian region is an important Neoproterozoic stratigraphic horizon in Liaoning Province where lots of carbonate rocks are developed.Based on the classical sequence stratigraphy theory,through the comprehensive analysis of field survey sections,the sequence stratigraphy of Sinian Ganjingzi Formation in Dalian is studied,and 5 sequence boundaries are identified,which are further divided into 4 third-order sequences,15 parasequence formations and 55 parasequences.The sedimentary facies of carbonate rocks can be divided into restricted platform and open platform subfacies,and subdivided into lagoon,tidal flat,low-energy subtidal and shoal microfacies.The regional tectonics and astronomical cycles are used to discuss the environmental evolution of Ganjingzi Formation.It is believed that process went through restricted platform→open platform→restricted platform.Under the influence of low-amplitude tectonic uplift and subsidence at the end of Yangtze cycle,5 short times of exposures took place during the late Nanguanling period-Ganjingzi period in Dalian area,which formed 5 sequence boundaries.Meanwhile,effected by periodic astronomical cycles,the high-frequency cycles of parasequences are formed.The study on the sequence stratigraphy and sedimentary evolution of Ganjingzi Formation in Dalian region provides a basis for the oil-gas exploration in southeastern Liaoning Province.