摘要:
安徽含山中志留世坟头组地层中已识别出三种不同沉积环境条件下的痕迹化石组合:(1) Protopaleodictyon (始网迹)组合,由Protopaleodictyon submontanum,Acanthorhaphe sp.,Planolites sp.1和Gordia cf.molassica组成,产生于海湾(河口湾)潮下过渡带环境;(2) Arenicolites (沙蠋迹)组合,包括定形的Arenicolites sp.,Skolithos sp.和Thalassinoides sp.以及Planokites sp.1,并共生无定形的生物扰动潜穴和各种不规则形态的倾斜潜穴,伴生有腕足类的Lingula,腹足类的Orthonota,Hormotoma和Ecculiomphalus以及三叶虫类的Coronocephalus等实体化石,形成了海湾(河口湾)的泥砂质岸滨环境;(3) Chondrites (丛藻迹)组合,以高度分枝潜穴系统Chondrites furcatus和C.arbuscula的富集为特征,含少量Planolites化石,丰度高分异度低,伴生有腕足类的Striispirifer和三叶虫类的Coronocephalus以及瓣鳃类和腹足类等实体化石,代表具有一定局限性的海湾潮下带贫氧的底层沉积环境。
Abstract:
Three trace fossil assemblages have been recognized in the estuarine deposits in the Middle Silurian Fentou Formation,Hanshan area,Anhui.
(1) The Protopaleodictyon assemblage mainly consists of Protopaleodictyon submontanum, Acanthorhaphe sp., Planolites sp. 1 and Gordia cf. molassica, and may be explained to be formed in a subtidal estuarine environment.
(2) The Arenicolites assemblage is made up of Arenicolites sp., Skolithos sp.,Thalassinoides sp., Planolites sp. 1 and irregular diagonal burrows as well as bioturhation structures, associated with some body fossils including the braehiopods Lingula, gastropods Orthonota, Hormotoma and Ecculiomphalus, and trilobites Coronocephalus, and is interpreted to be originated in a muddy-sandy coastal estuarine environment.
(3) The Chondrites assemblage is characterized by high-branched burrow systems including Chondrites furcatus and C. arbuscula, and contains a few of Planolites. It is an assemblage of high abundance and low diversity,and associated with some body fossils including the brachiopods Striispirifer,trilobites Coronocephalus, gastropods and bivalves and others, Which may serve to represent a locally restricted oxygen-deficient subtidal estuarine sedimentary environment.
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