一、前言四川盆地西部和西南部白垩纪和早第三纪地层发育,分布广泛,是研究我国中新生代地层界线的理想地区之一,但长期来由于缺乏古生物根据,地层的划分对比较为混乱,曾笼统将其归入白垩纪。1974年西南中生代地层座谈会,根据介形类和轮藻化石,认为盆地西部的“灌口组”上段和盆地西南“雷打树组”上段属早第三纪古新世。1975年王治、林元灿将盆地西部的早第三纪地层命名为“芦山群”。1976年四川省地质局区测队与我所合 I. Preface The Cretaceous and Early Tertiary stratigraphy in the western and southwestern Sichuan Basin is widely distributed and is one of the ideal areas for studying the Mesozoic-Cenozoic stratigraphic boundaries. However, due to the lack of palaeontology, the stratigraphic division has been rather chaotic , It has been generally classified as Cretaceous. According to the Mesozoic and Trachin fossils in the Southwest Mesozoic Stratigraphic Symposium in 1974, the upper member of the “Guankou Formation” in the western part of the basin and the upper segment of “Thunder Tree Formation” in the basin are of the Early Triassic Paleocene. In 1975, Wang Zhi and Lin Yuancan named the Early Tertiary strata in the western part of the basin “Lushan Group”. 1976 Geological Bureau of Sichuan Province team with me