Chapter Six Sediments Sedimentary Rocks Sediment Sediment loose
- Slides: 36
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 - 2 to 64 mm Sand - 1/16 to 2 mm Silt - 1/256 to 1/16 mm Clay - <1/256 mm
SEDIMENTATION AND SEDIMENTARY ROCKS I. INTRODUCTION IMPORTANCE OF SEDIMENTARY ROCKS: i) 75% OF ROCKS EXPOSED AT THE EARTH’S SURFACE ii) SOURCE OF FOSSIL FUELS, IRON AND ALUMINUM ORES, AND GROUNDWATER iii) RECORD OF EARTH’S HISTORY
TYPES OF SEDIMENT
II ORIGIN OF SEDIMENTARY ROCKS: A. INTRODUCTION 1. REVIEW OF WEATHERING PROCESSES: 2. CLASSIFICATION OF SEDIMENTS a) DETRITAL SEDIMENT: PREEXISTING FRAGMENTS OF PREEXISTING IGNEOUS, SEDIMENTARY AND METAMORPHIC ROCKS b) CHEMICAL SEDIMENT: PRECIPITATED FROM WATER OR EXTRACTED BY ORGANISMS AND DEPOSITED LATER B. SEDIMENT TRANSPORT AND TEXTURE 1. INTRODUCTION i) TRANSPORTATION AND DEPOSITION OF CHEMICAL SEDIMENTS ii) TRANSPORTATION AND DEPOSITION OF DETRITAL SEDIMENTS
2. GRAIN SIZE – CONTROLLED BY: a) NATURE OF PARENT ROCKS b) NATURE AND ENERGY LEVEL OF TRANSPORT MEDIUM 1) SORTING · WELL-SORTED: WIND MOST SELECTIVE POORLY-SORTED: GLACIERS AND FLOODING RIVERS SORT POORLY 2) CURRENT VELOCITY
Grain size • 3) GRAIN SHAPE - DEPENDS ON: • a) TRANSPORT MEDIA: SWIFTLY FLOWING RIVERS BOUNCE PEBBLES • • AND SAND GRAINS AROUND VIGOROUSLY • • b) DISTANCE FROM PARENT ROCK (AT THE BASE IF A GLACIER MAY • • BE GROUND TO A ROCKY POWDER) • • c)MINERAL HARDNESS:
Sediment in a Stream
C. SEDIMENTARY STRUCTURES: 1. BEDDING (STRATIFICATION): ARRANGMENT OF SEDIMENT PARTICLES INTO DISTINCT LAYERS a) CHANGES IN SEDIMENT: b) CHANGES IN TRANSPORT ENERGY 2. GRADED BEDDINGS: SEDIMENT LAYER (FORMED BY A SINGLE DEPOSITONAL EVENT) IN WHICH PARTICLE SIZE VARIES GRADUALLY WITH THE COARSEST PARTICLES ON THE BOTTOM
Development of a bedding plane
Develop. Bedding plane-contd.
Develop. Bedding plane contd.
Graded bedding of sediment
Development of cross-bedding
Cementation & Recrystallization • 4. CEMENTATION: PRECIPITATION OF DISSOLVED IONS IN THE PORE • • SPACE • a) CALCIUM CARBONATE • • b) SILICA • • c) IRON COMPOUNDS • • 5. CLASTIC TEXTURE: FORMED BY COMPACTION AND CEMENTATION OF • • SEDIMENT PARTICLES HAS CLASTIC TEXTURE • • 6. RECRYSTALLIZATION: RECRYSTALLIZATION OF CERTAIN UNSTABLE • MINERALS INTO NEW, MORE STABLE 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 SILT PREDOMINANTLY QUARTZ c) FINER-SIZED PARTICLES OF CLAY MINERALS
2. MUDSTONES a) MORE THAN HALF OF ALL SEDIMENTARY ROCKS b) CONTAIN THE SMALLEST PARTICLES (0. 004 mm IN DIAMETER) c) ENVIRONMENTS OF DEPOSITION: LAKES, LAGOONS, DEEP OCEAN BASINS, RIVER FLOODPLAINS d) COLOR VARIETY OF SHALE REPRESENTS MINERAL COMPOSITION e) PRACTICAL USES OF SHALE: BRICKS, CERAMICS, CEMENT, AND OIL 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) i) FORMATION ii) OOLITIC LIMESTONE iii) TUFA iv) TRAVERTINE
Cross-bedding & mudcracks 3. 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 ROCK • 1. DEFINITION OF DIAGENESIS: CHANGES IN THE SEDIMENT DUE TO INCRESED HEAT, PRESSURE, AND CIRCULATING GROUNDWATER • 2. DEFINITION OF LITHIFICATION: END RESULT OF DIAGENESIS • • 3. COMPACTION: DIAGENETIC PROCESS BY 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 Migration
Chapter Summary • • • • % 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 – deposition of shale Breccia and Conglomerate Oolitic Limestone Definition of Sedimentary Facies – Characteristics that distinguish one from another
- How does a igneous rock become a metamorphic rock
- Igneous metamorphic and sedimentary
- Lithification definition geology
- Chapter 6 sedimentary and metamorphic rocks answer key
- Erosion sedimentary rocks
- Esrt sedimentary rocks
- Sedimentary rocks examples
- Rocks concept map
- Organically formed sedimentary rocks
- Name
- Detrital sedimentary rocks
- Sedimentary rocks
- Characteristics of sedimentary rocks
- Types of clastic sedimentary rocks
- In sedimentary rocks lithification includes
- Features of sedimentary rocks
- Sedimentary rocks
- How is chert formed
- Clastic sedimentary rocks
- Erosion hawaii
- Facts on sedimentary rocks
- Metamorphic rocks characteristics
- Characteristics of sedimentary rocks
- Classify sedimentary rocks
- Formation of sedimentary rocks leaving cert
- Esrt sedimentary rocks
- Biochemical sedimentary rocks
- Pettijohn classification of sandstone
- Attritiom
- Magma facts
- 3 types of.rocks
- Biochemical sedimentary rocks
- Chemical sedimentary rocks definition
- Types of sedimentary rocks
- Organic sedimentary rocks
- Sandstone
- Type of rocks concept map