渤海湾盆地歧口凹陷古近系沙一段物源-沉积体系重建

采用布格重力异常手段宏观地区分物源区和沉积区，根据重矿物特征分析物源区位置及影响范围，依据地震反射特征识别物源运移方向，通过砂分散体系精细分析和表征物源-沉积体系特征，并利用岩石地球化学资料进一步佐证物源-沉积体系分析。综合研究表明，渤海湾盆地歧口凹陷沙一段时期存在五个物源区，分别为葛沽物源、小站物源、增福台物源、钱圈物源和北大港潜山物源。葛沽物源为板桥次凹提供沉积物，且沉积物主体呈两支向歧口主凹进一步推进；小站物源、增福台物源和钱圈物源影响范围较小，均呈两支进入板桥次凹；北大港潜山物源为歧北次凹提供沉积物，向马棚口和高尘头地区推进时物源频繁分叉。综合岩芯、录井、测井和古生物等沉积成因标志，认为板桥次凹发育扇三角洲沉积体系，歧口主凹和歧北次凹发育深湖浊流体系。

Reconstruction of Provenance-Sedimentary System of the First Member of the Paleogene Shahejie Formation in the Qikou Sag,Bohai Bay Basin

Accoding to the characteristics of the Bouguer gravity anomalies,the source and deposition areas were macroscopically distinguished in this paper.Based on the characteristics of heavy mineral,the location and extent of the source areas were described.In addition,the direction of the sources were determined on the basis of seismic reflection characteristics.Furthermore,the characteristics of provenance-sedimentary system were finely pictured by the distribution of sandbody,and could be further verified through geochemical characteristics.Different ways exerted respective superiority,and various means revised each other,the provenance-sedimentary system of the first member of the Paleogene Shahejie Formation in the Qikou sag of the Bohai bay basin was reconstructed by these ways.The results suggested that,there were five sources in the first member of Shahejie Formation in the Qikou sag,that were Gegu source,Xiaozhan source,Zengfutai source,Qianquan source and Beidagang buried hill source.The Gegu source was the largest source in the Qikou sag,the direction was overall the northwest to southeast,it provided sediments for Banqiao sag,and the sediments were further promoted into Qikou sag mainly in two directions but terminated at the downthrow wall of the Qizhong fault,the migration direction of the source location evolved from the southwest to the northeast in the first member of the Shahejie Formation,but the scale of the migration is small.The Xiaozhan source developed along Xiaozhan to Baishuitou area,the extent was small,the sediments were promoted into Banqiao sag in SSE and SE,the migration direction of the source location evolved from northeast to southwest.The scale of the Zengfutai source was limited which was influenced by the Dazhangtuo fault,the sediments filled into the Banqiao sag,and the source location migrated along northeast.The location of the Qianquan source was unstable,the migration direction of the source location evolved from west to northeast,the extent of migration was large scale,the sediments were promoted into Banqiao sag in two directions.The sediments of the Beidagang buried hill source were carried to the Qibei sag along the downthrow wall of the Gangxi and Gangdong fault and extended to the Zhangbei fault which showed from northwest to southeast,and being frequent bifurcation when impelled into Mapengkou and Gaochentou area.Combined with well cores,drilling,logging and paleobiology,it showed that Banqiao sag developed fan delta sedimentary system which was controlled by the Cangdong fault,that included fan delta plain,fan delta front and front-fan delta.The Qikou sag developed deep-lake turbidite sedimentary system which was influenced by the strong activity of Changlu fault,it was involved from the sandbody of the fan delta sedimentary system which controlled by the Gegu source.The Qibei sag developed deep-lake turbidite sedimentary system located in the background of the semi deep-lake and deep-lake controlled by the Gangxi and Gangdong fault.The distribution of sedimentary system was obviously influenced by the direction,shape and extent of the source area.The research proved that this comprehensive analysis of multi-methods was effective for the reconstruction of provenance-sedimentary system.