CEE 1030 1nd Edition Lecture 6 Sediments and Sedimentary Rock Outline of Last Lecture I Dangers of ash II Review III Earth s external processes IV Types of weathering V Soil formation Outline of Current Lecture I Review II Sedimentary rocks III Sediments vs sedimentary rocks IV Types of sedimentary rock a Detrital b Chemical c Organic V Sedimentary structures VI Sedimentary environments a Sedimentary facies Current Lecture I II III Review a Factors that speed up rates of chemical weathering in rocks high temperatures high rainfall Sedimentary rocks a Product of mechanical and chemical weathering b Contain evidence of past environments c Only rock type to contain fossils d Economically important host oil gas uranium and coal deposits source of sand and gravels for construction e Vertical changes in sedimentary rock types represent environmental changes through time Sedimentary vs sedimentary rocks a Sediments collection of loose solid particles b Sedimentary rock particles bound together to form a firm coherent rock c Lithification unconsolidated sediment to rock These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV V i Compaction layers of sediment press water out ii Cementation crystals cement sediments together Types of sedimentary rocks a Detrital sediment transported as solid particles i Main constituents clay minerals quartz feldspar mica rock fragments ii Particle size used to distinguish types 1 Particles 2 mm in diameter a Conglomerate rounded particles b Breccia sharp angular particles 2 Sand sized particles 0 0625 2 mm a Sandstone quartz is dominant mineral 3 Poorly sorted particles big mixed with small particles 4 Fine particles 0 0625 mm mudstone shale a Siltstone and clay stone test see difference by chewing the rock gritty is siltstone smooth is clay stone b Shale silt and clay particles form thin layers or laminated during compaction b Chemical formed from material that was once in solution in water i Limestone most abundant chemical rock composed mainly of calcite or polymorph aragonite ii Oolitic limestone inorganic made of small particles called ooloids iii Biogenic limestones coral reefs shell fragments microorganisms 1 Coquina poorly cemented rock of shell fragments 2 Fossiliferous limestone shell fragments cemented with calcite cement iv Dolostone made of dolomite forms from limestone as Mg rich water passes through rock v Chert hard compact microcrystalline SiO2 in nodules and layers often in limestone beds also known as flint breaks off sharply so used as arrowheads in cultures vi Evaporates evaporations of water triggers deposition of chemical precipitates c Organic remains of decayed plants i Accumulating plant matter especially in swampy environments ii Coal formation organic sedimentary rocks under compaction Sedimentary structures a Provides important information about environment of sedimentation b Most common characteristic of sedimentary rocks form sub horizontal beds or strata bedding planes separate strata c Cross bedding and current ripples i Can see distinct ripples on sediment for example sand dunes d Graded beds vertical change in particle size VI e Mud cracks evidence that sediment was alternately wet then dry wet mud shrinks as it dries out forming cracks Sedimentary environments a Geographic setting where sediment accumulates determines the nature of sediments that accumulate b Continental environments c Shoreline environments d Marine environments e Sedimentary facies i Different sediment types often accumulate adjacent to one another at the same time