滇东寒武系层序地层学特征

    CAMBRIAN SEQUENCE STRATIGRAPHY OF EASTERN YUNNAN

    • 摘要: 介绍了对滇东寒武系进行层序地层学研究所采用的方法、层序的基本特征及取得的主要成果。确定有10个层序,其时限为1~10Ma,其中下寒统武有6个,中、上寒武统各2个。此外还划分出次层序27个、组合层序2个。此项研究工作对本区寒武系地层划分与对比、界线的确定具有重要意义:(1)沧浪铺阶生物地层的争论,是由于滇东存在两个Ⅰ型层序边界,乌龙箐段与红井哨段为假整合关系,故生物带发育不完整;(2)双龙潭组与西王庙组应为同时异相沉积体;(3)双龙潭组顶部时限,以SB2i为标志,应与娄山关组底部边界对比,故可能上延至晚寒武世早期

       

      Abstract: Field sequence stratigraphic analysis of the Cambrian strata of eastern Yunnan permits recognition of ten sequences, each with a time interval of 1-10 Ma. There are six sequences in the Early Cambrian, two in the Middle Cambrian and two in the Late Cambrian. Each sequence is subdivisible into two to five subsequences: There are a total of 27 subsequences. According to the forms of accumulation of the deposits, the relative lowstand (RL) and relative highstand (RH) and sometime condensed interval (CI) may be distinguished.The study of sequence stratigraphy has important significance for the stratigraphic correlation and boundary determination, which is manifested as follows: (1) There is dispute over the biostratigraphy of the Canglangpu Stage. As two Itype sequence boundaries exist in eastern Yunnan, the contact between the Wulongqing Member and the Hongjingshao Member is disconformable. The biozones are not complete, so the scheme of size biozones proposed by Zhou Zhiyi should be adopted. (2) The Shuanglongtan and Xiwangmiao Formations are both synchronous heteropic deposits, marked by SB 2h and SB 2i. (3) The top boundary of the Shuanglongtan Formation is marked by SB 2i, which may be correlated with the base boundary of the Loushanguan Formation. Its age may range upward into the early Late Cambrian.

       

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