【摘要】 湘西中、上寒武统花桥组和车夫组主要由斜坡相和盆地边缘相的碳酸盐岩、泥质碳酸盐岩及钙质泥岩组成。重力流沉积十分发育，其中花垣排碧剖面以碎屑流砾屑灰岩和近源浊积岩为主；永顺王村剖面以浊流沉积为主；桃源瓦尔岗剖面则以远源浊积岩为主。成岩作用主要为海底埋藏胶结作用、新生变形作用和白云石化作用。排碧剖面大多数岩样酸不溶物重量含量在１０％以下，王村和瓦尔岗剖面大多数岩样在１０％以上。全岩δ１８Ｏ值介于－１１．２‰至－５．６‰（ＰＤＢ）之间；δ１３Ｃ值为－１．９‰至３．４‰（ＰＤＢ）。从Ｌｉｎｇｕａｇｎｏｓｔｕｓｒｅｃｏｎｄｉｔｕｓ带开始，δ１３Ｃ有较大的正漂移，漂移值达３‰（ＰＤＢ）以上。沉积花桥组和车夫组时，湘西过渡区经历了４次海平面升降事件，台缘斜坡逐渐变陡，由缓坡型逐渐发展为镶边型和沟槽型。在湘西的诸多剖面中以王村剖面最适合于作为中、上寒武统界线层型候选剖面，界线选择在花桥组顶部。更多还原

【Abstract】 Huaqiao and Chefu formations of the Middle and Upper Cambrian in western Hunan a re mostly composed of alternating beds of argillaceous and lime-riched carbon at es (calcilutites to calcirudites) containing gravity flow deposits, which consi s t of shallow water limestone clasts and identifiable allochems derived from the adjacent Yangtze Platform. Debris flow sediments mainly occurring near Paibi vi l lage in Huayuan County represent upper continental slope deposits. The formation s in Wangcun, Yongshun County, comprising turbidites and autochthonous sediments , are interpreted to have been deposited in the lower slope belt. While the unit s consisting of distal turbidites and hemipelagic sediments in Wa′ergang, Taoyu a n County, suggest basin margin environments. Diagenetic processes mainly include burial cementation, neomorphisms and dolomization. The whole rock δ 13 C(PDB) values of the well preserved carbonates range b etween - 1.9‰ and 3.4‰, and the δ 18 O(PDB) values range from -11.2‰ to -5.6‰. A large posi tive δ 13 C excursion begins with the first occurrence of Linguagnostus r econditus. The excursion reaches values of more than 3‰. Most rock samples ha ve less t ha n 9 wt% MgO. The lowest CaO content is 11.8%, and the highest is 53.4%. Generall y, rocks from Paibi section contain <10wt% acetic-acid-insoluble residues; whe re as the acetic-acid-insoluble residues content of rocks from Wangcun and Wa′er gang sections is more than 10%. Four eustatic events of sea level are interpreted from the deposits of Huaqiao a nd Chefu formations by means of facies analysis and sequence stratigraphy. Three condensed sections containing pyrite and spongy bone needle indicate that deepe st water deposition occurred near the beginning of the Ptychagnostus atavus and Lejopyge laevigata biochorons, and the midway within the P. punctuousus biochron . The forth occurred in Gushan Stage. Incipiently drowned platform and ramp evol ved into accretionary platform and steepened ramp. Of all sections, richly fossi liferous, easily accessible, excellently exposed and continuous stratigraphic section in Wangcun is most competitive candidate section for the middle-upper c ambrian boundary stratotype.更多还原