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朝鲜平南盆地与东华北克拉通(中朝克拉通)中新元古代盆地的对比存在争议,准确厘定相关沉积建造的沉积时限是解决这些争议的关键。朝鲜平南盆地的地层主体为祥原超群,从下往上依次为直岘群、祠堂隅群、默川群、灭恶山群和燕滩群。直岘群是祥原超群的最下部层位,大部分由陆源碎屑岩组成。从平南盆地“北部型”和“南部型”直岘群碎屑岩中分选锆石,测得LA-ICP-MS U-Pb年龄,限定祥原超群沉积时代晚于1100Ma,并且得出所谓的“北部型”和“南部型”地层没有时代和物源差异。鉴于默川群的基性岩床时代为~900Ma,祥原超群的沉积时代为新元古代早期(1000~900Ma),燕滩群的时代可能稍晚。这说明平南盆地与华北徐淮盆地和旅大盆地等同时。祥原超群碳酸盐岩样品的δ~(13)C值数据表明,默川群时期碳同位素发生了负漂移(δ~(13)C值为-6‰~-5‰)。鉴于侵入到默川群的基性岩床的时代为~900Ma,我们认为该碳同位素(δ~(13)C值)负漂移略早于~900Ma,可能与同一时期的岩浆活动有关。
The contradiction between the Neoproterozoic basins in North China’s Pingnan basin and the East China Craton (China-North Korea Craton) is controversial. It is the key to solve these disputes accurately to determine the deposition time limit of the related sedimentary structures. The stratigraphic main body of the Pingnan Basin in North Korea is the Xiangyuan superb group, which is the straight Daoxian group, the Ancestral Temple corner group, the Suochuan group, the Micious Mountain group and the Yantan group from the bottom up. Straight Daoxian group is the lowest level of the Cheung original, most of the terrigenous clastic rock. Zircons were sorted from Straight Daoxian clastic rocks in the Pingnan Basin “North Type” and “Southern Type” strata. LA-ICP-MS U-Pb ages were measured to determine that the Cheungwon superdepositional depositional period was later than 1100 Ma , And come to the conclusion that there is no difference of epoch and provenance in the so-called “North Type” and “Southern Type” strata. In view of the age of Mesozoic bedrock of ~ 900 Ma in the Early Triassic, the epoch of the Cheungwon prehistoric period was the early Neoproterozoic (1000 ~ 900 Ma), the age of the Yantan group may be slightly later. This shows that the Pingnan Basin and North China Xuhui Basin and Luda Basin at the same time. The δ ~ (13) C data of the Xiangyuan ultra-carbonate samples show that the carbon isotopes have a negative drift (δ ~ (13) C value of -6 ‰ ~ -5 ‰) during the Meichuanqu Period. In view of the fact that the age of the basic bedrock infiltrated into the Mochuan Formation was ~ 900 Ma, we believe that the carbon isotope (δ ~ (13) C) value slightly drifts slightly earlier than ~ 900 Ma, which may be related to magmatic activity in the same period.