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Sedimentary Rocks. Sedimentary Rocks - Those rocks that form from the aggregation of sediments that have been transported, deposited, and later lithified. Sediments are essentially fragments and particles of other rocks and/or minerals. How is a sedimentary rock produced?.
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Sedimentary Rocks • Sedimentary Rocks - Those rocks that form from the aggregation of sediments that have been transported, deposited, and later lithified. • Sediments are essentially fragments and particles of other rocks and/or minerals.
How is a sedimentary rock produced? • The Sedimentation Process - producing sediments. • Weathering and Erosion • Transportation • Deposition • Lithification Process - How to convert sediments into rocks. • Compaction • Dehydration • Cementation
Sedimentary Rocks • Two types of sedimentary rocks based on the sources of their major components - • 1. Detrital sedimentary rocks - composed of particles call detritus, which means rock particles and/or minerals from other rock types. Also known as Clastic! • 2. Chemical sedimentary rocks - composed of precipitates or chemicals that were in solution within a liquid, usually water. Note Biochemical used by textbook.
Sedimentary Rocks • Detrital Sedimentary Rocks - • These rocks are composed of other rock types. Quartz is one of the most resistant rocks to weathering and is a dominate component of many sedimentary rocks. • Gravel = Conglomerate or breccia 2-> 256 mm • Sand = Sandstone 1/16-2 mm • Mud = Mudstone to shale < 1/16 mm
Sedimentary Rocks • Chemical Sedimentary Rocks • These rocks are composed of materials carried in solution within lakes and oceans and/or of a biological origin. • Limestone from dissolved CaCO3 • Conquina is a coarse rock composed mostly of loosely cemented shells and shell fragments. • Chert, flint, agate, etc. is from SiO2 • Evaporites are salts - rock gypsum • Coal - from organic material
Sedimentary Rocks • The importance of these rocks is that they typically make-up 75 volume % of the upper most part of continental crust and are expressed as strata or beds or rock layers. • Strata are the record of paleo-environments.
Sedimentary Rocks • The study of strata, beds, and their respected paleo-environments is the science of stratigraphy. • Stratigraphic formation -sequence of strata distinctive enough to be traced across a large region. • Special kinds of Bedding - Cross beds and graded beds.
Sedimentary Rocks • Sedimentary Environments - these are environments where sediments were deposited. • Glaciers, mountain streams, alluvial fans, sand-dunes, lake, ponds, rivers, etc. • Reflective of a specific type of depositional energy.
Sedimentary Rocks • What processes produce sediments? • Weathering - disintegration and decomposition of rock at or near surface (Mechanical and chemical) • Mass wasting - transfer of rock material down-slope under the influence of gravity. • Erosion - incorporation and transportation of material by a mobile agent, usually water, wind, and/or ice.
