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由于在川西北地区二叠纪-三叠纪界线地层的白云岩中一直没有找到可靠的生物化石,长期以来,白云岩就成为划分该地区二叠纪-三叠纪界线的标志。严格来说,这是一条岩石地层界线,而不是真正意义上的生物地层界线。在对四川江油渔洞子剖面进行详细的生物地层和沉积相研究时,在二叠纪长兴组珊瑚层以上的灰质白云岩中发现了微生物岩层并在其中首次找到了牙形刺H.parvus和灾难种有孔虫化石,从而为我们精确划分川北地区二叠纪-三叠纪的界线生物地层及确定该地区白云岩与微生物岩的时代及生态环境变化提供了可靠的生物化石依据。沉积特征的分析有利于了解从晚二叠世长兴组顶部至早三叠世飞仙关组中下部的沉积历史。
Due to the fact that no reliable biological fossils have been found in the Permian-Triassic stratigraphic dolomites in northwestern Sichuan, dolomites have long been the hallmark of the Permian-Triassic boundary. Strictly speaking, this is a lithosphere boundary, not a true biological boundary. In a detailed study of the biostratigraphy and sedimentary facies of the Yudong Formation in Jiangyou, Sichuan Province, microbial strata were found in the gray-level dolomites of the Permian Changxing Formation above the coral stratigraphy and for the first time, H. parvus and catastrophes were found Foraminiferal fossils, which provided a reliable biological fossil basis for the precise division of Permian-Triassic boundary bio-stratigraphy in North Sichuan and determination of the age and ecological environment changes of dolomite and microbial rock in the area. The analysis of sedimentary features is helpful to understand the sedimentary history from the top of Changxing Formation in Late Permian to the middle and lower part of Feixianguan Formation in Early Triassic.