贵州关刀剖面中-晚三叠世之交牙形石生物地层再研究  

RESTUDY ON CONODONT BIOSTRATIGRAPHY ACROSS THE MIDDLE-LATE TRIASSIC BOUNDARY AT THE GUANDAO SECTION,GUIZHOU,SOUTH CHINA

作　　者：覃斌贤 江海水[2] 陈龑 吴先浪 QIN Bin Xian;JIANG Hai Shui;CHEN Yan;WU Xian Lang(School of Tourism Management,Guilin Tourism University,Guilin 541006;School of Earth Science,China University of Geosciences,Wuhan 430074)

机构地区：[1]桂林旅游学院,旅游管理学院,广西桂林541006 [2]中国地质大学(武汉)地球科学学院,湖北武汉430074

出　　处：《地层学杂志》2023年第3期306-323,共18页Journal of Stratigraphy

基　　金：国家自然科学基金(41830320、41972033);科技部基础性工作专项(2015FY310100-11)共同资助。

摘　　要：贵州省南部关刀地区在三叠纪位于南盘江盆地内的大贵州滩北西缘,属于碳酸盐台地边缘斜坡相沉积环境。关刀剖面因产出丰富的三叠纪牙形石而备受关注,前人已对该剖面的牙形石进行了详细的报道。本文在前人研究的基础上,详细重建了关刀剖面中-晚三叠世之交的牙形石序列,识别出安尼期晚期至卡尼期早期的8个牙形石间隔带,由下至上分别为:Neogondolella cornuta带、Budurovignathus truempyi带、Budurovignathus hungaricus带、Budurovignathus mungoensis带、Paragondolella inclinata带、Paragondolella foliata带、Quadralella polygnathiformis带和Quadralella intermedius带。其中,Paragondolella foliata带和Quadralella intermedius带首次识别于该剖面。据此,本文重新厘定了该剖面拉丁阶的底界和顶界。其中,以Budurovignathus truempyi的首现为标志,将拉丁阶的底界下移了14.8 m;以Budurovignathus mungoensis的首现为标志划分出了拉丁阶内Fassanian与Longobardian亚阶的界线;以Quadralella intermedius的首现代替Quadralella polygnathiformis的首现作为拉丁阶顶界的标志,将该剖面的上三叠统底界下移了10.2 m。The Guandao Section occurs on the basin-margin slope on the northwestern flank of an isolated carbonate,the Great Bank of Guizhou in the Nanpanjiang Basin of south China during the Triassic.The previous studies demonstrated detailed conodont sequences through the Triassic at the Guandao Section,due to the well-exposed Triassic marine stratigraphic sequences.In this study,we enable a detailed conodont biostratigraphic restudy on the Middle-Late Triassic transition at the Guandao Section combined with previously reported data.A total of eight late Anisian-early Carnian conodont interval zones were recognized,in ascending order,including the Neogondolella cornuta Zone,the Budurovignathus truempyi Zone,the Budurovignathus hungaricus Zone,the Budurovignathus mungoensis Zone,the Paragondolella inclinata Zone,the Paragondolella foliata Zone,the Quadralella polygnathiformis Zone and the Quadralella intermedius Zone.Among these zones,the Paragondolella foliata Zone and the Quadralella polygnathiformis Zone are recognized for the first time at this section.Based on the updated distribution of conodonts,the relative(sub)stage boundaries of the Ladinian stage at Guandao are refined.The base boundary of the Ladinian stage is marked by the first occurrence of Budurovignathus truempyi,about 14.8 m lower than the previous definition.The Fassanian-Longobardian boundary is defined based on the first occurrence of Budurovignathus mungoensis.The top boundary of the Ladinian stage is redefined by the first occurrence of Quadralella intermedius,about 10.2 m lower than the previous definition by the first occurrence of Quadralella polygnathiformis.

关 键 词：牙形石 生物地层 三叠纪 间隔带 贵州南部 

分 类 号：P534.51[天文地球—古生物学与地层学]