摘要
滇西保山地区广泛发育奥陶系−志留系仁和桥组黑色岩系。为了建立其笔石地层时空对比框架,以云南保山市施甸县半坡剖面和茶地剖面为研究对象,开展了生物地层学和岩石学研究。研究表明,研究区仁和桥组总厚度约71.6 m,底部发育一层厚约25 cm的古风化壳,与下伏蒲缥组呈平行不整合接触,证明研究区在晚奥陶世曾暴露于地表。基于高分辨率笔石化石调查,识别出了上奥陶统赫南特阶至志留系兰多维列统特列奇阶共9个笔石带,自下而上依次为Metabolograptus persculptus带(仁和桥组第1笔石带,后续简称R1)、Akidograptus ascensus带(R2)、Parakidograptus acuminatus带(R3)、Cystograptus vesiculosus带(R4)、Coronograptus cyphus带(R5)、Demirastrites triangulatus带(R6),Lituigraptus convolutus带(R7),Stimulograptus sedgwickii带(R8)和Spirograptus guerichi带(R9)。与扬子地区龙马溪组笔石生物地层对比表明,保山地区仁和桥组9个笔石带能够与龙马溪组LM1~LM9笔石带相对应。此研究成果为保山地区仁和桥组页岩气调查评价建立了良好的笔石生物地层学基础。
The Ordovician to Silurian Renheqiao Formation,characterized by a sequence of well-preserved black shales,is extensively developed in the Baoshan region,southwestern Yunnan Province,China.[Objective]The primary goal of this study is to establish a graptolite biostratigraphic framework for the Renheqiao Formation.To achieve this,the research focuses on the Banpo and Chadi sections in Shidian County,Baoshan City,Yunnan Province,which are critical outcrops for biostratigraphic analysis in the area.[Methods]A combination of highresolution biostratigraphic and lithologic records was conducted to precisely define the stratigraphy and identify key biozones within the formation.[Results]The Renheqiao Formation in the study area is approximately 71.6 meters thick,with a about 25 cm of paleo-weathering crust at the base.It unconformably overlies the Pupiao Formation,indicating that the study area was subaerially exposed during the Late Ordovician.Based on detailed fieldwork and high-resolution surveys,a total of nine graptolite zones were identified,spanning from the upper Hirnantian in the Ordovician to the Silurian Llandovery Telychian stage.These identified graptolite zones are in ascending order as follows:the Metabolograptus persculptus zone(R1),Akidograptus ascensus zone(R2),Parakidograptus acuminatus zone(R3),Cystograptus vesiculosus zone(R4),Coronograptus cyphus zone(R5),Demirastrites triangulatus zone(R6),Lituigraptus convolutus zone(R7),Stimulograptus sedgwickii zone(R8),and Spirograptus guerichi zone(R9).[Conclusion]The nine graptolite zones of the Renheqiao Formation in the Baoshan region correlate well with those of the Longmaxi Formation(LM1–LM9)in the Yangtze region.This correlation not only strengthens the regional stratigraphic framework but also provides a solid basis for future shale gas exploration and assessment in the Baoshan region.
作者
郑书粲
冯庆来
龙精杰
陶振鹏
ZHENG Shucan;FENG Qinglai;LONG Jingjie;TAO Zhenpeng(School of Architectural Engineering of Huanggang Normal University,Huanggang Hubei 438000,China;School of Earth Science,China University of Geoscience(Wuhan),Wuhan 430074,China;Hunan Province Geological Disaster Survey and Monitoring Institute,Changsha 410029,China)
出处
《地质科技通报》
北大核心
2025年第4期256-272,共17页
Bulletin of Geological Science and Technology
基金
湖北省自然科学基金计划项目“滇西下志留统仁和桥组黑色岩系成烃生物类型对有机质富集的影响机理研究”(2024AFB337)
黄冈师范学院高级别培育项目“保山地块仁和桥组黑色泥页岩成烃生物演化规律研究”(202525404)
湖北省教育厅哲学社会科学研究项目“鄂东古生物化石的调查、发掘与开发利用研究”(23Q072)
中石化勘探分公司项目“保山地块页岩气资源调查与评价”(合同编号“35450003-22-ZC0607-0003”)。
关键词
奥陶系−志留系
仁和桥组
笔石生物地层
龙马溪组
滇西保山地区
Ordovician-Silurian
Renheqiao Formation
graptolite biostratigraphy
Longmaxi Formation
Baoshan region,southern Yunnan
