摘要
江西乐平沿沟剖面均一的碳酸盐相岩沉积,完整地记录了二叠系-三叠系界线附近生物演变过程.通过对该剖面系统的化石切片研究,共鉴别出有孔虫27属39种,包含类4属7种.该剖面有孔虫的演变在二叠纪-三叠纪之交呈现出单幕式的消减过程,对应于华南两幕生物灭绝中的第1幕.有孔虫的个体数和多样性在21-2层顶部发生了突然降低.4个不同有孔虫组合的演替关系,揭示了有孔虫在灭绝事件中的演变过程,即由灭绝前的高丰度、高分异度组合转变为灭绝后低丰度、低分异度组合.通过对二叠系-三叠系界线处鲕状灰岩的化石和沉积特征研究,发现Hindeodus changxingensis带内的鲕状灰岩中仍存在较为丰富的有孔虫等化石.剧烈的海平面变化以及鲕状灰岩形成使下伏地层中的化石颗粒发生再沉积作用,是形成这一特殊现象的主要原因.通过对鲕状灰岩中化石和沉积特征的深入研究,论证了该鲕状灰岩形成于二叠纪-三叠纪之交大灭绝之后,是当时特殊的海洋生态系产物,反映了当时较高的海水回旋速率、微生物繁盛、海水碳酸盐超饱和等异常的环境条件.
The homogeneous carbonate Permian-Triassic boundary section at Yangou records the integrated extinction process of the shallow marine area,which killed over 90% marine invertebrates.This study of foraminifers explores the extinction pattern and deposition progress during the Paleozoic-Mesozoic transition.In total,39 species in 27 genera of foraminifers have been identified,including 7 species in 4 genera of fusulinids.The richness and diversity remarkably decrease at the top of Bed 21-2,marking the disappearance horizon.4distinct assemblages evolved within the Permian-Triassic boundary beds：the assemblages with low richness and low disparity replaced those with high richness and high disparity.The diversity and assemblage analysis exhibit a rapid decline process at the top of Bed 21-2.Whereas,the mixing of pre-extinction fauna,fusulinids,with postextinction fauna,Hindeodus changxingensis,within the oolitic beds,implies that the fossil could be reworked to the shoal bythe sea level changes.Meanwhile,the coating of foraminifers and aragonite-calcite cement around the grains indicate a catastrophic ocean with high water velocity,elevated microbes and carbonate super-saturation.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2014年第11期1473-1486,共14页
Earth Science-Journal of China University of Geosciences
基金
国家重点基础研究发展计划(No.2011CB808800)
国家自然科学基金项目(Nos.41272372
41240016
41302271
41302010)
中央高校基本科研业务费专项资金生物地质与环境地质国家重点实验室自主研究课题(Nos.GBL11202
GBL11302)
现代古生物学和地层学国家重点实验室开放课题研究计划(No.133111)
江西省教育厅科技计划项目(No.GJJ14735)
