辽河坳陷雷家地区沙四段富有机质页岩沉积环境及有机质聚集影响因素OA

The Es4 Member in the Leijia Area of the Liaohe Depression contains abundant organic-rich shales.To further elucidate the depositional conditions and key controls on organic matter accumula-tion,this study conducted total organic carbon(TOC),major element,and trace element analyses on shale samples from a key well.The results indicate that the w(TOC)values of the Es4 Member shale are generally high,with three high w(TOC)intervals developed at the bottom,middle,and upper-middle layers.The shale samples exhibit high w(V)/w(Cr)ratios,low w(Mo)concentrations,and low w(Ti)contents,suggesting they deposited in an anoxic environment with limited input of coarse-grained terrig-enous detritus,which favored organic matter preservation and provided a foundation for its accumula-tion.The w(Ni)/w(Al),w(Cu)/w(Al),and w(P)/w(Ti)values show positive excursions in the bot-tom,middle,and upper-middle layers,correlating well with w(TOC)variations,indicating that paleo-productivity fluctuations are key factors controlling the vertical change of w(TOC)values.Variations in w(Al)/w(Ti)ratios exhibit an intrinsic relationship with w(P)/w(Ti),w(Ni)/w(Al),and w(Cu)/w(Al)trends,implying that lake-level fluctuations also influenced organic matter accumulation.This study provides important insights for shale oil exploration and development in the Leijia Areaofthe Liao-he Depression.