Presentation on theme: "Sedimentary Rocks Sedimentary Rocks - Those rocks that form from the aggregation of sediments that have been transported, deposited, and later lithified."— Presentation transcript:
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 CaCO 3 Conquina is a coarse rock composed mostly of loosely cemented shells and shell fragments. Chert, flint, agate, etc. is from SiO 2 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.
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 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 Next?
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.