Sediments sedimentary rocks

Chapter Six Sediments & Sedimentary Rocks Sediment • Sediment - loose, solid particles originating from: – Weathering and erosion of pre-existing rocks – Chemical precipitation from solution, including secretion by organisms in water • Classified by particle size – – – – – – Boulder - >256 mm Cobble - 64 to 256 mm Pebble - to 64 mm Sand - 1/16 to mm Silt - 1/256 to 1/16 mm Clay - [...]... • • • • • • % of sedimentary rocks in outer 10 miles Basic classification of sedimentary rocks Most sedi Rocks – Chemical or detrital Definition of sedimentary rocks Sorting by wind, glaciers (well sorted vs poor sorting) Degree of sedimentary particle rounding Bedding plane, sedimentary structure, occurrence Diagenesis, Lithification, Cementation Composition of detrital sedimentary rocks Environment... MINERALS • III CLASSICATION OF SEDIMENTARY ROCKS: DETRITAL SEDIMENTARY ROCKS: • • • • MUDSTONES SANDSTONES CONGLOMERATES BRECCIAS A DETRITAL SEDIMENTARY ROCKS: 1 INTRODUCTION: CLASSIFICATION BASED ON PARTICLE SIZE a) ALL DETRITAL ROCKS ARE CLASTIC b) SAND AND SILT PREDOMINANTLY QUARTZ c) FINER-SIZED PARTICLES OF CLAY MINERALS 2 MUDSTONES a) MORE THAN HALF OF ALL SEDIMENTARY ROCKS b) CONTAIN THE SMALLEST... SHALE 3.SANDSTONES: a) 25% OF ALL SEDIMENTARY ROCKS b) SANDSTONE PARTICLES (1/16-2 MM IN DIAMETER) c) PRACTICAL USES OF SANDSTONES: BUILDINGS AND RESERVOIR FOR FOSSIL FUELS AND GROUNDWATER 4.CONGLOMERATES AND BRECCIAS a) GRAINS LARGER THAN 2 MM b) CONGLOMERATES HAVE ROUNDED GRAINS c) BRECCIAS HAVE ANGULAR GRAINS B CHEMICAL SEDIMENTARY ROCKS 1 INORGANIC CHEMICAL SEDIMENTARY ROCKS a) LIMESTONE (INORGANIC)... WHICH THE WEIGHT OF OVERLYING MATERIALS REDUCES THE VOLUME OF SEDIMENTARY BODY Lithification of sediment Initial deposits of flat/tabular clay Formation of ooliths Locations of subsurface evaporite Formation of coal from swamp deposits Formation of coal –contd Common geological environment Geology at a glance Marine sedimentary environment Sedimentary facies formation Sedi Facies formation – contd Landword... CROSS-BEDDING: SEDIMENTARY LAYERS DEPOSITED AT AN ANGLE TO THE UNDERLYING SET OF BEDS 4 SURFACE SEDIMENTARY FEATURES a) RIPPLE MARKS: SMALL SURFACE RIDGES PRODUCED WHEN WATER OR WIND FLOWS OVER SEDIMENT AFTER IT IS DEPOSITED b) MUDCRACKS: OCCUR ON THE TOP OF A SEDIMENT LAYER WHEN MUDDY SEDIMENT DRIES AND CONTRACTS Origin of mud cracks Asymmetric and symmetric ripples D LITHIFICATION: TURNING SEDIMENT INTO SEDIMENTARY. .. sedimentary structure, occurrence Diagenesis, Lithification, Cementation Composition of detrital sedimentary rocks Environment – deposition of shale Breccia and Conglomerate Oolitic Limestone Definition of Sedimentary Facies – Characteristics that distinguish one from another