对山东省第四纪史家沟组划分的再认识

Classification of Shijiagou Formation in Quaternary in Shandong Province

史家沟组的时代归属一直存在争议。在系统梳理山东省史家沟组地层划分沿革的基础上,对蓬莱、长岛和无棣3个地区的11个史家沟组露头剖面进行系统采样,获取了14个K-Ar年龄和2个ESR年龄,通过与前人测年数据对比分析,发现在山东境内仅在无棣碣石山(0.87 Ma)和蓬莱市北沟镇迎口山(1.51 Ma)出露有第四纪更新世玄武岩,其他测试年龄均为新近纪(9.24-5.02 Ma)。蓬莱和长岛地区的玄武岩地层多属中新世晚期(蓬莱北沟镇迎口山除外)尧山组,仅有少量属第四纪史家沟组。建议将无棣大山、蓬莱北林院迎口山区域玄武岩划为第四纪,其他区域出露的第四纪史家沟组划为新近纪。

The chronological age of Shijiagou Formation is always controversial.On the basis of systematical summary of the stratigraphic division of Shijiagou Formation in Shandong Province,the authors in this paper have systematically sampled 11 profile outcrops of Shijiagou Formation in Penglai,Changdao and Wudi,and obtained 14 K-Ar ages and 2 ESR ages.Through the comparative analysis with previous dating data,it is found that Quaternary Pleistocene basalt is only exposed in Jieshi Mountain(0.87 Ma)in Wudi and Yingkou Mountain(1.51 Ma)in Beigou Town,Penglai City in Shandong,while other test ages are Neogene(9.24-5.02 Ma).The basalt strata in Penglai and Changdao areas mostly belong to the Yaoshan Formation in the Late Miocene(except for Yingkou Mountain in Beigou Town of Penglai City),while only a few belong to the Quaternary Shijiagou Formation.It is suggested that the basalt in Wudi Mountain and Yingkou Mountain of Beilinyuan in Penglai should be classified as Quaternary,and the Quaternary Shijiagou Formation exposed in other areas should be classified as Neogene.