浙西桐庐县桐君山下志留系安吉组风暴沉积

浙江西部桐君山剖面下志留系安吉组可确认出一套浅海风暴沉积,发育三种不同类型的风暴层序,其中包含盆内泥砾、丘状层理、反递变层理及其他沉积构造。在正常和风暴波基面之间的地带,其中部风暴层序发育最佳,由此向海向陆均趋简单化。风暴砂层是由振荡流、风暴流、推移质和悬移质共同作用形成的,并且是由异地沉积而不是残留砂改造而成。

Storm Deposition of ANJI Formation of Silurian,Tongle County,Tongjun Hill,Western Zhejiang Province

A set of storm deposits can be identified in Tongjun Hill profile, Anji Formation, Lower Silurian. Three kinds of different sequences, that is, rock assemblages, sedimentary structures and erosive features can be distinguished in the zone between normal and storm wavebases, the best developed one is characterized by large amounts of bedding types and the complex bedding assemblage, and the other two sequences tend to be more simple seawards and landwards. Both oscillation current and seaward bottom unidirectional current occured in storm water-regime lead to the coexistence of bed load and suspended load in storm deposition, which can be recognized, as an important indicator. The horizontal occurrence of the storm sand indicates that the sediment supply is derived from adjacent land rather than from relict sand, which illustrates that the storm sand is allochthonous sediment.