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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 carbonate sediments deposited along the levee profile in Leping, Jiangxi Province completely record the biological evolution near the Permian-Triassic boundary.According to the fossil sections of this section system, 27 foraminifera species Including 4 genera and 7 species.The evolution of foraminifera in this section showed a monoclear abatement process at the turn of the Permian-Triassic period, corresponding to the first act of the two extinctions in South China. The number of individuals and their diversity abruptly decreased at the top of the 21-2 layer.The succession relationship of the four foraminiferal assemblages revealed the evolution of foraminifera in the event of extinction, Degree and high-degree assemblage changed to low-abundance and low-degree assemblage after extinction.Based on the study of the fossil and sedimentary characteristics of the oolitic limestone at Permian-Triassic boundary, it was found that oolitic in the Hindeodus changxingensis zone Limestone is still rich in foraminifera fossils and other fossils.The dramatic changes in the sea level and the formation of oolitic limestone so that the underlying strata of fossil particles redeposition, is the formation of this special phenomenon of the main reasons In-depth study of fossil and sedimentary characteristics in oolite limestone, It is demonstrated that the oolitic limestone formed after the Permian-Triassic mass extinction and was the product of a special marine ecosystem at that time, reflecting the then high rates of sea water gyration, the flourishing of microorganisms and the over-saturation of seawater carbonate Abnormal environmental conditions.