朝鲜平南盆地埃迪卡拉系-下寒武统地层碳同位素特征  

Characteristics of carbon isotope of the Ediacaran and Lower Cambrian strata in the Pyongnam basin,DPR Korea

作　　者：金明哲[1] 杨正赫 彭澎[2] 翟明国[2] 朴贤旭 冯连君[2] 李忠日[1] 朱成赫 

机构地区：[1]朝鲜国家科学院地质研究所,平壤3812100 [2]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029

出　　处：《岩石学报》2016年第10期3180-3186,共7页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41210003)资助

摘　　要：中朝古陆(华北古陆)平南盆地位于朝鲜半岛中部,广泛发育新元古界-古生界地层。根据化石记录,一般认为燕滩群(自下而上包括飞狼洞组和棱里组)主体属于埃迪卡拉系,黄州(超)群坪山组和中和组主体属于下寒武统。然而,该套地层记录的新元古界-古生界界线处在什么位置,燕滩群是否记录冰期事件(如,Gaskiers冰期),尚有争议。本文对这些地层开展了碳、氧同位素分析。结果表明,飞浪洞组δ13C值从底部+2‰开始,在+2‰和+6‰之间变化,最上部为+2‰;棱里组从下到上从0降至-7‰;坪山组在-3.1‰~0‰之间变化;中和组基本上在-1.2‰^+1.9‰范围变化。这些数据表明,原先认为有冰碛岩的飞浪洞组可能没有记录Gaskiers冰期;棱里组δ13C值与Gaskiers或Marinoan等冰期不可对比,而可能对应于埃迪卡拉系最末期的负漂移。通过将平南盆地燕滩群-黄州群地层碳同位素值变化趋势与国际地层对比,明确地层时代属于埃迪卡拉系末期-下寒武统;由于不存在明确的的不整合,燕滩群-黄州群地层可以作为这一时期连续剖面。我们认为黄州群坪山组底部含磷、含金属硫化物黑色板岩可以作为界线标志层。The Pyongnam basin of the Sino-Korean block（ North China block） lies in Middle Korean Peninsula and contains extensive Neoproterozoic to Early Paleozoic strata.Based on fossils,it is generally accepted that the Yontan Group（ Pirangdong and Rungri Fms.from bottom up） belongs to the Ediacaran while the Pyongsan and Junghwa Fms.of the Hwangju（ Super-） group belong to the Lower Cambrian.However it is yet unclear whether the Yontan Group records glaciation（ e.g.,the Gaskiers glaciations） and where is the boundary between the Neoproterozoic and the Early Paleozoic.Carbon and oxygen isotope study show that the δ13C values start from ＋ 2 ‰ at the bottom,vary between ＋ 2 ‰ ～ ＋ 6 ‰,and finally back to ＋ 2 ‰ in the Pirangdong Fm.,from 0 to-7 ‰ in the Rungri Fm.,between-3.1 ‰ and 0 ‰ in the Pyongsan Fm.,and from-1.2 ‰ to ＋ 1.9 ‰ in the Junghwa Fm.The data negate the previous thought that there is tillite in the Pirangdong Fm.,which recorded the Gaskiers period.The negative drifting in the Rungri Fm.cannot match those during the Gaskiers or Marinoan period glaciation but is possibly corresponding to the drifting at the end of the Ediacaran.Based on a comparison of the carbon isotope variations with the global trend,it verifies that the Yontan Group and the Pyongsan and Junghwa Fms.of the Hwangju Group deposit during the Late Ediacaran-Early Cambrian.As there is no clear unconformtiy,the two groups can be regarded as a continuous section of the Late Ediacaran-Early Cambrian,and we propose that the phosphorous and sulphide-bearing black slate in the bottom of the Pyongsan Fm.of the Hwangju Group could be the boundary layer.

关 键 词：朝鲜半岛 中朝古陆(华北古陆) 埃迪卡拉系 下寒武统 碳同位素 负漂移 

分 类 号：P534.1[天文地球—古生物学与地层学] P597.2[天文地球—地质学]