冀北滦平盆地九佛堂组—沙海组叶肢介化石的发现与陆相建阶问题的讨论

The discovery of the conchstracan fossils in Jiufotang Formation and Shahai Formation of Luanping Basin, north Hebei Province, and discussion of established stage of the land facies strata

2007—2008年,在滦平县西瓜园东滦河南岸发现九佛堂组底部砾岩与西瓜园组连续的直接接触关系,其后,又在滦平以西巴克什营至滦平公路鹞子梁发现九佛堂组底部砾岩鹞子梁砾岩,并向西追索到拉海沟北的得胜岭北山,九佛堂组剖面就是从得胜岭北山鹞子梁砾岩底部开始向北测制。在滦平县以西的山湾、杨树沟、小乔木沟、德胜岭等地都采到了叶肢介化石,特别是在该组下部采集到了阜新东方叶肢介和九佛堂东方叶肢介;顶部采集到了沙海组的典型分子延吉叶肢介属的几个种,证明在滦平盆地西瓜园组之上、阜新组(青石砬组)之下确有九佛堂组—沙海组,解决了长期以来有关滦平盆地"大西瓜园组"或"大九佛堂组"的争论。至此,大北沟组、大店子组、西瓜园组、九佛堂组与沙海组的叶肢介化石组合序列初步建立起来。结合滦平盆地晚期中生代沉积盆地演化,讨论有关陆相建阶问题,结合前人资料,冀北-辽西晚期中生代自下而上拟初步建立三宝营阶(土城子阶)、榆树下阶(大北沟阶)、张家沟阶(原大店子组)、李营阶(义县阶)、鹞子梁阶(九佛堂阶)-清河门阶(沙海阶)、海州阶和"孙家湾阶",以供今后讨论有关陆相建阶问题时参考。

In 2007 and 2008,abundant chonchostracan fossils were collected from Cretaceus Jiufotang Formation and Shahai Forma-tion at Shanwan Village,Yangshugou Village,Xiaoqiaomugou Village,and Deshengling Village in Luanping County,Hebei Province.The conchostracan fossils are divided into 6 genera and 26 species,including one new genus and 22 new species.According to the stan-dard of an erected stratotype,many methods were used.The authors divided the section into three lithologic units,and erected five con-chostracan biostratigraphic assemblages.Therefore,it is suggested that the occurrence of conchostracan Eosestheria fuxinensis and Eoses-theria jiufotangensis should be regarded as the indication of the bottom boundary.At the same time,the land facies Stage of the Jurassic and Cretaceous strata is established as Sanbaoying Stage,Yushuxia Stage,Zhangjiagou Stage,Liying Stage,Yaoziliang Stage,Qinghemen Stage,Haizhou Stage,and Sunjiawan Stage in the Northern Hebei Province and Westhern Liaoning Province,China.