沉积学报2025，Vol.43Issue(2)：387-407,21.DOI:10.14027/j.issn.1000-0550.2023.022
扬子西北缘二叠纪瓜德鲁普统—乐平统界线识别及意义
Identification and Significance of the Permian Guadelup-Lopingian Series Boundary in the Northwestern Margin of the Yangtze Craton
摘要
Abstract
[Objective]The Guadelup-Leping boundary(PLB boundary)of the Middle-Late Permian has long been considered a difficult academic issue for geoscientists.On the one hand,the uplift movement at the turn of the Middle and Late Permian caused a sedimentary discontinuity and differential denudation,which made determining the boundary and comparing it with the global profile difficult.On the other hand,the reason several profiles recorded negative carbon isotope drift events related to the PLB boundary with different occurrence is still unclear.[Methods]This study selected seven sections of the late Guadalupian strata(including Sandui Town,Wangjiagou,Daliang Township)along the northwest margin of the Yangtze Plate as research object and identified the formation time limit through lithological characteristics and conodonts.Major trace and rare earth element analyses also complement the environmental evidence of regional carbon isotope drift events.[Results]The results show that:(1)From the Jinogo-ndolla.postserrata to Clarkina.dukouensis zone,the field sections can be divided into four lithologic sections,bioclas-tic limestone(containing dolomite),siliceous limestone(argillaceous limestone),coal seam,and marl-bearing lime-stone,representing three stages of sea level:stabilization-decline-rise.(2)The characteristic key bed of the PLB boundary identified based on the paleoexposure,lithologic mutation,and first appearance surfaces of the C.dukouen-sis is marked as the lowest Leping boundary.(3)Two regression events were recorded in the J.postserra-J.shannini zone and J.altudaensis-J.xuanhanensis zone of the Sandui Town profile,resulting in synchronous negative deviation of Sr/Ba and Y/Ho values and relative enrichment of light rare earth elements.[Conclusions]The Emeishan Large Igneous Province began to move in the J.altudaensis belt,and the input of hydrothermal fluid caused a sharp increase in the total rare earth elements in the region.The biological population was affected by the extinction event in the J.postserrata belt that lasted until the PLB boundary.This study complements the profile evidence by explaining the differences in the timing and period of negative carbon isotope deviation events between the northwest margin of the Yangtze Craton and the global records.关键词
扬子板块/生物地层/牙形石/PLB界线/生物灭绝Key words
Yangtze Craton/biostratigraphy/conodont/PLB boundary/biological extinction分类
地质学引用本文复制引用
刘宣威,田亚铭,姜福杰,王鹏威,张慧,柳昊,李飞..扬子西北缘二叠纪瓜德鲁普统—乐平统界线识别及意义[J].沉积学报,2025,43(2):387-407,21.基金项目
国家自然科学基金项目(41872128)[National Natural Science Foundation of China,No.41872128] （41872128）
