论文部分内容阅读
二叠纪-三叠纪之交的钙质微生物岩相地层序列完整地记录了该重大转折期的生物和环境突变过程.通过对湖南慈利康家坪剖面二叠系-三叠系界线附近生物地层序列、碳同位素演变、沉积微相和化石面貌研究,识别出Palaeofusulina-Colaniella带、Hindeodus parvus带和Isarcicella staeschei带.该剖面微生物岩处碳同位素出现显著负偏,并且与生物含量突然减少基本同步.识别出5种微相类型,分别是:藻-有孔虫生物碎屑灰岩、藻纹层状钙质微生物岩、鲕粒灰岩、蠕虫状泥灰岩和内碎屑粒泥灰岩.研究结果表明,慈利地区古、中生代之交由生物礁迅速演变成微生物岩相的生态演变,代表了海相生态系的主幕转变过程.
Permian-Triassic calcareous microbial lithostratigraphic sequence completely records the biological and environmental catastrophe during this period of great turning-point. By comparing the sequence of the Permian-Triassic boundary in Cangli, Hunan Stratigraphic sequence, carbon isotopic evolution, sedimentary microfacies and fossil facies, Palaeofusulina-Colaniella zone, Hindeodus parvus zone and Isarcicella staeschei zone were identified.The carbon isotopes of microbial rocks at the section were significantly negatively biased and basically synchronized with the abrupt decrease of biomass Five microfacies types were identified: algae-foraminiferal bioclastic limestone, algal laminar calcareous microbial rock, oolitic limestone, vermicular marl and internal detritus marl The results show that the paleozoic and Mesozoic alternations in Cili area rapidly changed from reef to microbial ecology and represented the main screen change process of marine ecosystem.