2-1地史学-沉积古地理学.ppt

Chapter 2 Sedimentary paleogeography第2章 沉积古地理学 2.1 concepts and laws 2.2 sed.-facies indicators 2.3 sed. environments (自主互动) 1 Sed. environments 2 Sedimentary facies 3 Facies changes and analysis of sed-facies 4 Walther’s law 5 Uniformitarianism 1 沉积环境(sedimentary environments): 一个具有独特的 物理、化学和生物 特征的自然地理单元 3 相变——地层的岩石特征和生物特征及其所反映的沉积环境和沉积作用在空间（横向）上的变化。 Facies changes? 相分析三要素 Methodology– a detective’s approach Induction（归纳）; Deduction（演绎） 2.1 Concepts and law Sketch showing Walther’s law Significance for Walther’s Law 2.1 Concepts and law What is an Uniformitarianism Example-1 Brachiopods（Productida, O3-P) 将古论古-蜓 Zoophycos Desiccation cracks  Syneresis cracks, 1500Ma, 大红峪组 Desiccation cracks  Syneresis cracks, 1200Ma, 北大尖组 Biostabilization 将今天论未来 Deep biosphere-1 Deep biosphere-2 Deep biosphere-3 生命的温度界限 生命的酸碱度界限 Uniformitarianism; 类比分析The present is the key to the past 将今论古 将古论今 将古论古 将今论未来 将天论地 将地论天 The End * * * * * 2.1 Concepts and laws 2 沉积相(Sedimentary facies)——反映沉积记录成因（环境、条件和沉积作用）的岩石特征和生物特征的综合。即沉积记录成因的物质表现。 岩相(lithofacies, petrofacies) 生物相(biofacies) Carbonate facies Shale facies Sandstone facies Shale coal facies Facies changes Facies sequence 4 相分析(facies analysis)——综合地层的岩石特征和生物特征，推断其成因（沉积环境和沉积作用） ● Material ● Principles ● Methodology Subaerial, most likely semi-humid environment 1000Ma Mudcracks+Raindrops A palaeo-scene (the evidence) They are dinosaur footprints and they can tell us about: Group behavior; Seasonality temperature; Food web competition intensity; Their living environment Your interpretation: 1 Sed. environments 2 Sedimentary facies 3 Facies changes and analysis of sed-facies 4 Walther’s law 5 Uniformitarianism ●Stratigraphical conformities ● Gradual transgression How about regression? transgression 瓦尔特相（定）律亦称相对比原理(J Walther，1894) :只有那些目前可以观察到是相互毗邻的相和相区，才能原生地重叠在一起; 即在垂向上整合叠置的相是在侧向上相邻的沉积环境中形成的。 Walther’s law (rule) or law of facies correlation : Only those facies and facies-areas can be sup