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Sediments and Sedimentary Rocks. Sediments and Sedimentary Rocks. And. Pressure. Cementation. Erosion. Sedimentary Rocks. Sediment. Erosion. Heat. Erosion. Pressure. Heat and Pressure. Igneous Rocks. Metamorphic Rocks. Cooling. Heat. Magma. Sediments ( soft )
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Sediments and Sedimentary Rocks And Pressure Cementation Erosion SedimentaryRocks Sediment Erosion Heat Erosion Pressure Heat and Pressure Igneous Rocks MetamorphicRocks Cooling Heat Magma
Sediments (soft) Material (such as gravel, sand, mud, and lime) that is transported by wind, water, ice, or gravity; Material that is precipitated from solution; Deposits of organic origin (such as coal and coral reefs). Sedimentary Rock (hard) Rock formed by the accumulation and consolidation of sediment.
Sediments - unconsolidated particles created by 1. The weathering of rock 2. The secretions of organisms or decomposition of organic matter 3. Chemical precipitation
Sedimentary Rocks • Composed of lithified sediments • by compaction • by cementation Two (Textures) - clastic -nonclastic
Types of Sediments Clastic Nonclastic 1. Biogenic 2. Chemical
Types of Sediments • 1. Clastic – broken fragments of rock produced by weathering. Range in size from largest boulder to smallest clay particle. Classified according to size. Found everywhere on the Earth.
Clastic Texture Texture - Size, shape, and distribution of particles that collectively make up a rock • Size • Rounding • Sphericity • Sorting
Clastic Texture • Roundness – the shape of sediment grains. • Related to the distance a sediment has been transported. Sphericity - how close to a spherical shape a grain is or will be.
Size Rounding Sphericity Sorting
Clastic Sediments Sorting • Sorting – separation of sediments by grain size and density. Poorly sorted – sediment with a wide range of grain sizes. Well sorted – sediment with a small range of grain sizes.
Sorting - a function of transported 1. Water 2. Wind 3. Glaciers
Texture and Transport Distance • In general, as transport distance increases, rounding and sorting increase. Examples: Breccia – cemented close to source Conglomerate – transported then cemented
Sorting by Water Graded Beds
Graded Beds Fining up
Clast Size / Rock Name Relationship Large Clasts Small Clasts
Breccia - Formed at the source
Conglomerate – Formed near the source
Sandstone – Down stream to just off shore
Tidal Flat Deposit Stream Deposit
Strata Stratum Stratigraphy Stratigraphic • relating to layered • sedimentary rocks
Bedding – Layering or stratification in sedimentary rock
Types of Sediments • 2. Biogenic – composed of remains of plants or animals.
Biogenic Sediments Terestrial Sediments - mainly plant matter Marine Sediments - mainly carbonates Corals - Large components of reefs. Bivalves, Gastropods, Foraminifers - Whole or partial skeletons form sand and gravels. Aglae, Crinoids, Echinoderms, Bryozoans - disintergrate to form some sand particles and lime mud. Diatoms, Radiolaria – Bedded chert SiO2
Types of Sediments • 3. Chemical – formed by minerals precipitating from solution. Inorganic process, no biological activity involved.
Chemical Sediments 1. Terestrial - Evaporites: Gypsum - CaSO4 . H2O Anhydrite - CaSO4 Halite - NaCl 2. Marine - Carbonates - CaCO3 (Whitings)
Sedimentary Rocks Clastic Rock – composed of fragments of preexisting rocks. Nonclastic Rock – composed of chemical precipitates or biogenic matter.
Depositional Environments Where sedimentary rock live!