Questions and Answers
What is the process of sedimentary rocks?
- Weathering occurs first, along with erosion. 2) Soluble constituents are carried off by runoff, wind, groundwater, gravity, glacial ice, and bodies of water. 3) These particles are deposited and compacted/cemented.
What are detrital sedimentary rocks?
Rocks formed from solid sediments (mud, sand, and gravel) derived from both chemical and mechanical weathering.
What are chemical sedimentary rocks?
Rocks formed from ions in solution that precipitate by inorganic or biological processes.
What are organic sedimentary rocks?
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What are the three categories of sedimentary rocks?
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What are two ways that sedimentary rocks are important?
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How does the volume of sedimentary rocks in the Earth's crust compare to the volume of igneous and metamorphic rocks?
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What minerals are most abundant in detrital sedimentary rocks?
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Outline the steps that transform an exposure of granite in the mountains into various sedimentary rocks.
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What is the primary basis for distinguishing among detrital rocks?
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What is shale?
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What is sandstone?
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What does poorly sorted mean?
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What does well sorted mean?
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What is the difference between conglomerate and breccia?
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What is the primary characteristic feature of sedimentary rocks?
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What portion of land does sedimentary rocks and sediments cover?
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Study Notes
Sedimentary Rock Processes
- Formation begins with weathering and erosion, followed by deposition, compaction, and cementation of sediments.
- Soluble materials are transported by various forces like water, wind, and glacial ice.
Types of Sedimentary Rocks
- Detrital Sedimentary Rocks: Created from solid sediments like mud, sand, and gravel through chemical and mechanical weathering.
- Chemical Sedimentary Rocks: Formed from ions in solution that precipitate due to inorganic or biological processes.
- Organic Sedimentary Rocks: Result from the compaction and lithification of carbon-rich remains from organisms.
Importance of Sedimentary Rocks
- Provide insights into Earth's history and geological processes.
- Act as reservoirs for essential resources, including fossil fuels, metals, and groundwater.
Sedimentary Rock Volume
- Sedimentary rocks constitute a small volume in Earth's crust (5-10%) compared to igneous and metamorphic rocks (90-95%).
- Cover approximately 75% of land surfaces and dominate ocean floors.
Composition of Detrital Rocks
- Predominantly contain clay minerals and quartz, with clays mainly from silicate mineral weathering.
- Quartz is durable, primarily sourced from igneous rock, especially granite.
Transformation of Granite to Sedimentary Rock
- Granite undergoes mechanical and chemical weathering, producing quartz, feldspar, clay, and ions.
- These materials are moved by natural forces and eventually deposited and compacted into detrital and chemical sedimentary rocks.
Characteristics of Detrital Rocks
- Distinction based on particle size:
- Shales and mudstones (silt and clay-sized)
- Sandstones (sand-sized)
- Conglomerates and breccias (gravel-sized)
- Rounding and sorting of grains help further classification.
Types of Sedimentary Rock Textures
- Non-clastic (Crystalline) Texture: Formed through mineral crystallization.
- Clastic Texture: Composed of broken fragments and cemented together.
Environmental Settings for Sedimentation
- Includes continental, marine, and transitional environments, which dictate sediment accumulation processes.
- Erosion and deposition dominate continental environments, while marine environments are classified by water depth.
Sedimentary Structures
- Facies: Variations in sedimentary deposits.
- Bedding planes and cross-bedding indicate past environments and sediment transport dynamics.
- Ripple marks and mud cracks provide clues about historical conditions.
Biochemical and Chemical Sedimentation
- Biochemical sediments arise from organic processes in aquatic organisms, while chemical sediments originate from inorganic processes.
Importance of Diagenesis and Lithification
- Diagenesis refers to all changes post-deposition.
- Lithification transforms loose sediments into solid rock through compaction and cementation, processes that depend on burial depth and pressure.
Resource Identification
- Common cements such as silica, calcium carbonate, and iron oxides can be identified through distinct properties.
- Limestone and dolostone differ in composition and reaction to acid, with limestone being more common.
Carbon Cycle Relevance
- Sedimentary processes, including biochemical sediment formation, play a critical role in carbon cycling, sequestering carbon from the atmosphere into geologic formations.
Coverage of Sediments
- Sedimentary rocks and sediments cover roughly 75% of land surfaces and extensively blanket ocean basins.
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Description
Test your knowledge of sedimentary rocks with these flashcards. Learn about the processes involved in their formation and the various types, including detrital sedimentary rocks. Perfect for geology students wanting to solidify their understanding of sedimentary processes.
