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Chapter 7: Sedimentary Rocks. Introduction. What is a sedimentary rock? Sedimentary from “sedimentum” = to settle 5 vol% of Earth 75% of Earth’s surface B/c deposited at Earth’s surface Economically important e.g. coal, petroleum & fertilizers e.g. major sources of Fe, Al, Mn.
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Introduction • What is a sedimentary rock? • Sedimentary from “sedimentum” = to settle • 5 vol% of Earth • 75% of Earth’s surface • B/c deposited at Earth’s surface • Economically important • e.g. coal, petroleum & fertilizers • e.g. major sources of Fe, Al, Mn
Turning Sediment into Rock • Diagenesis: • From “dia” = change and “genesis” = origin • Collective term for chemical, physical & biological changes after deposition & during and after lithification • Lithification: • From “lithos” = stone and “fic” = making • Process by which unconsolidated sediments are transformed into sedimentary rocks • Compaction: • The reduction of pore space due to high confining pressure • Cementation: • Precipitation of minerals in the pore spaces, binding the individual grains together
Type of Sedimentary Rocks • Detrital (AKA Clastic) • A sedimentary rock derived from the accumulation of solid particles created from mechanical & chemical weathering • Chemical • A sedimentary rock derived from precipitation of dissolved substances produced largely from chemical weathering
Detrital Sedimentary Rocks • Particle Size • Larger = more energy to move • Sorting • How similar the particle sizes • Well sorted = longer transporation time • Rounding • More round = more processing
Chemical Sedimentary Rocks • Inorganically or organically produced • Biochemical • Common Organic Types • Limestone • Coquina • Chalk • Common Inorganic Types • Dolostone (AKA Dolomite) • Chert and Agate • Evaporites
Chalk • Made up of microscopic organisms
Agate A) Chert B) Flint C) Jasper
Sedimentary Environments • Deposition Environment = Sedimentary Environment • Geographic setting where sediment is accumulating • Types • Continental • Marine • Transitional
Continental Environments • Streams Glaciers Wind (aeolian)
Strata (beds) Bedding planes Cross-bedding Graded beds Ripple marks Mud cracks Fossils Strata & Bedding Planes Sedimentary Structures