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辽西四合屯发掘和野外考察表明，四合屯及周边地区义县组下部地层由三段组成：第一段冲积相粉碎屑岩；第二段中基性火山熔岩；第三段滨一浅湖、半深湖二深湖相砂岩和页岩构成2个正旋回．其中第三段有上、下2个脊椎动物化石层位：尖山沟上部脊椎动物化石层和四合屯下部脊椎动物化石层．在四合屯厚度gm的发掘剖面上肯定了10个含鱼层、1个含蛙层、3个含龟层、5个含恐龙层和5个含鸟层．四合屯以鸟类和爬行类为代表的化石群埋藏于厚度166cm，富集于厚度84cm的湖相页岩中，记录了佛罗一白垩纪界线附近重大生物演化事件和脊椎动物集群死亡事件．孔子鸟和中华龙鸟不存在厚度14m的上下层位关系．湖相层凝灰岩和重力流事件沉积，反映盆地曾经为一水域宽阔、火山活动频繁的泛盆地．
Excavation and field investigation in Sihetun, western Liaoning Province show that the lower part of the Yixian Formation in Sihetun and surrounding areas is composed of three sections: the first alluvial-phase clastic rocks; the second-stage basic volcanic lava; the third section of Haidian-Shallow Lake, Semi-deep lake two deep lacustrine sandstone and shale constitute two positive cycles. The third section has two upper and lower vertebrate fossil beds: the Jianshangou upper vertebrate fossil layer and the Sihetun lower vertebrate fossil layer. There are 10 fish layers, 1 frog layer, 3 turtle layers, 5 dinosaur layers and 5 bird layers in the excavation section of Sihetun thickness gm. The fossil assemblages represented by birds and reptiles in Sihetun are buried in a thickness of 166 cm and are enriched in lake shale with a thickness of 84 cm. Major fossil evolution events and vertebrate cluster death events near the Cretaceous-Cretaceous boundary are recorded . Confucius bird and Chinese dragon bird there is no relationship between the upper and lower layers of thickness 14m. The lacustrine tuff and gravity flow events have been deposited, reflecting that the basin was once a pan basin with a wide area and volcanic activity.