西秦岭北带泥盆纪遗迹群落在浊积岩系中的分布特征  

Distribution Characteristics of Trace Forssil Group in Turbidite Measure (Devonian) in the Northern Belt of West Qinling Mountains

作　　者：晋慧娟[1] 李育慈[1] 

机构地区：[1]中国科学院兰州地质研究所

出　　处：《沉积学报》1997年第1期13-19,共7页Acta Sedimentologica Sinica

基　　金：国家自然科学基金

摘　　要：本文重点研究内容是：１）舒家坝组时代的厘定和层序叠置关系；２）遗迹群落总体概况以及各遗迹属确定的依据；３）浊流沉积作用控制遗迹群落的形成及其分布特征。通过本文研究不难看出，舒家坝组的４３个遗迹化石属可划分为两大类。一是形成于浊流间歇期缓慢沉积的泥岩层面，主要为“深水型”遗迹分子；另一是产于浊流突然事件来临及其后快速堆积的砂岩内，包括“浅水型”和“穿相型”分子。就其分异度和丰度而言，虽均以前者最高，但这两类遗迹化石组合共生在一个沉积剖面。trace fossil ichnogenera have been found in Devonian Shujiaba Formation distributed in the northern belt of West Qinling Mountains, and they are Acanthorhaphe, Arthophcus, Belorhaphe, Bostricophyton, Buthotrephis, Cochilichnus, Chondrites, Cosmorhaphe, Dictyodora, Fucusopsis, Glockeria, Gordia, Granularia, Helicolithus, Helminthoida, Helminthopsis, Lennea, Lophoctenium, Megagrapton, Neonereites, Nereies, Palaeohelminthoida, Paleodictyon, Planolites, Protopaleodictyon, Protovirgularia, Rhabdoglyphus, Rhobdoichnus, Rusophycus(?), Saerichnites, Sagittichnus, Scolicia, Skolithos, Spirophycus, Spirorhaphe, Squamodictyon, Sublorenzinia, Subularia, Subphyllochorda, Taphrhelminthoida, Taphrhelminthopsis, Tuberculichnus, Urohelminthoida. All the host rocks of trace fossils mentioned above are turbidite deposits, so it is easy to see that there exists a close link between the formation of trace fossil and turbidity process. According to the time of pre and post turbidity current event, two sharply different fossil assemblages can be recognized, and they are: 1) Trace fossil assemblage formed before turbidity event They are produced in a low energy abyssal environment in the interval of tubidity process, with two typical features:①animals live and seek for food horizontally in the surface deposits, and trace fossils are mainly preserved in the Te mudstone surface of the Bouma sequence; ② Generally, they appear in curve, snake and network shapes, of which over 70% ichnogenera are formed before the turbidity event. And they are the typical members of ' Nereites' facies with high degree of differentiation and abundance features. 2) Trace fossil assemblage formed after turbidity event They are of low abundance and degree of differentiation, and are characterized by the irregular 'shallow water' and 'spanning facies' type members, generally preserved in the sandstone parts of the Bouma sequence or piercing sandstone. They are not in the leading role among the fossils discovered. Although the abundance and degre

关 键 词：泥盆纪 地层 遗迹群落 古生物 浊积岩 分布特征 

分 类 号：Q946.44[生物学—植物学] P588.2[天文地球—岩石学]